A Synthesis of Sildenafil

A Synthesis of Sildenafil For many reasons, this route was assumed suboptimal as a commercial manufacturing for example; it is linear with nine steps, sulphonyl chloride, which is one of the toxic substances produced from this route is in the final bond-forming reaction. Final material required a lot of recrystallizations to reduce the toxic impurities to appropriately low levels in order to produce the high quality of drug required by pharmaceutical company. Due to competing hydrolysis through the increased quenched times on scale-up chlorosulphonation in chemical development; the difficulties of scaling-up reactions are well-known. In this route, 2-pentanone and diethyl oxalate are condensed to give the diketoester 1. Then, cyclizating the diketoester by hydrazine produces pyrazole 2 which methylated with selective to give pyrazole3. Hydrolysing the reaction generated the acid 4, then convert acid to the amide by nitration to give nitropyrazole 5, which is common intermediate in all synthetic routes. Reduction of 5 with tin (II) chloride dehydrate to give the amine 6 which is by 2-ethoxybenzoyl chloride was acylated to produce diamide 7. The later was cyclized using aqueous sodium hydroxide and hydrogen peroxide to result in 8 pyrazolo[4,3-d]pyrimidin-7-one. Sildenafil was produced by selective chlorosulfonation and reaction with N-methylpiperazine.(6) Optimization of the cyclization reaction to make the pyrimidinone was the key finding during the development of the medicinal chemistry route, which impacted on the programme as a whole. Cyclization of compound 4 was done by sodium hydroxide and hydrogen peroxide, which are an aqueous alcoholic solution and lead to moderate yield (30-70%). The hydrolysis of the carboxamide to give the acid either in the presence or absence of the hydrogen peroxide was the main side product from the medicinal reaction. To avoid the hydrolysis side product, cyclization was conducted under anhydrous conditions, KOtBu/ButOH and the reaction continued in 100% product without detected impurities. By considering reordering the steps, the clean cyclization was the final bond-forming reaction. (1) Modification of the medicinal route: A lot of modifications were applied into medicinal chemistry route, which was used at the beginning of the project to prepare fifty kilograms and support supply for the four years. (6) For early scale-up, the tin (II) chloride reduction was removed. Tin is major environmental polluter and a heavy metal. It was replaced with a catalytic hydrogenation. At the early age of the sildenafil production, a tin chloride reduction was employed because the hydrogenation reduction was not in operation. The reason for inefficient of the hydrogenation was a presence of trace levels of sulfur impurities which poison the hydrogenation reaction. Switching to stoichiometric thionyl chloride is one example that controlled sulfur impurities and allows the reliability of the catalytic hydrogenation reaction. Using a hydrogenation, there are options for solvent and catalyst recovery and water is the only by-product. (5) Hydrogen peroxide was used in cyclization method to convert 7 to 8, but it causes skin burns. Furthermore, in contact with organic materials, it is a fire and transportation hazardous. Then, it was replaced with KOtBu/ButOH. Rather than using oxalyl chloride, thionyl chloride is used to prepare 2-ethoxybenzoyl chloride which eliminates exposure to carbon monoxide emissions by workers. (5) Through formation of pyrazole 3 which is an exothermic reaction, a solvent was introduced. Moreover, for 5 preparations, toluene was introduced as a solvent which reduces the level of thionyl chloride from 1.6 to 1.8 equivalents. (6) Sildenafil Citrate Sildenafil Commercial Route: Selection: The target from Sildenafil citrate was for treatment of angina when entered development. But the clinical results were failed. Pfizer made a trial with 12 patients tolerate from male erectile dysfunction in 1994. The results showed improvements in the problems of 10 patients. As a consequence, sildenafil citrate development became one of the highest priorities in the Pfizer portfolio (6). There are many advantages of commercial route over the optimized medicinal one, for example; The synthesis was redesigned to make convergence. The final bond forming step is the clean cyclisation reaction and at the start of the synthesis, the potentially toxic materials occur. Large volumes of aqueous acidic waste require an increased level of hydrolysis and neutralization through a larger scale is an example of environmental and scale-up issues associated with chlorosulphonation reaction. In order to reduce these issues, they are placed at the start of the synthesis. Hence, low molecular weight and cheaper materials are used. (5). DEVELOPMENT: Sulfonamide preparation: Through pyrazole 5, many routes of synthesis proceeded. Using chlorosulfonic acid, 2-ethoxybenzoic acid is Chlorosulfonated by using 1 mol of thionyl chloride to convert the intermediate sulfonic acid to the sulfonyl chloride. Due to low melting point of 2-ethoxybenzoic acid (19-20 C) mp, low molecular volumes of chlorosulfonic acid and thionyl chloride are used and hence no solubilisation. Initially, the sulfonamide 9 was isolated as unusual double salt 10 which is insoluble and difficult to use. Moreover, in order to obtain the double salt to crystallize, the sulphonyl chloride should be dry which lead to a lot of acidic, corrosive fumes in a pilot plant scale. Then, it was discovered that 9 can be isolated as its highly crystalline zwitterions by treatment the double salt with water to dissociate and produce a new form of free crystalline amino acids 8. For efficiency, the sulfonyl chloride was converted to sulfonamide 9 by resuspended in water and reaction with N-methylpiperazine. At the end of the reaction, by the addition of aqueous sodium hydroxide, the pH was adjusted to the isoelectric point and the precipitated compound 8 collected by filtration. As a result, during sulfonamide preparation, no organic solvents are used. Hydrogenation and coupling reaction: In medicinal chemistry, the tin (II) chloride reduction was replaced by a palladium catalyzed hydrogenation reaction to convert pyrazole 1 into the amide2. Toluene was introduced as a heat solvent which increased the safety of the process and reduced the levels of thionyl chloride to 1.2-1.6 equivalents. To convert the nytropyrazole (2) to the amine (3) heterogeneous hydrogenation in ethyl acetate was used. A number of reagents, including thionyl chloride, oxalyl chloride and N,N-cabonyldiimidazole (CDI) are used to examine the activation of the carboxylic acid. CDI costs around 8$/mol and provide such advantages for instances; high quality product, robust and clean chemistry. Furthermore, it provided a combination of the three reactions (hydrogenation, acid activation and acylation) into a single step, employed the ethyl acetate solvent with a simple recovery process and used low energy. In addition, VOC emissions were avoided such as (EtCl) that generated from the interaction of ethyl chloride with thionyl chloride or oxalyl chloride. Moreover, 90% chemical yield over three chemical reactions is produced and optimized to 96%. Cyclisation Reaction: The resulting product is heated for several hours and cyclised with 1.2 equivalents of potassium t-BuOH and t-BuOK. In order to minimize the environmental wastes, this process is run at high concentration (2.5-3.75L Kg-1). Water is added to dilute the reaction and the pH was adjusted with 4M HCl to the isoelectric point (7.5). Clinical very high quality yield of 95% sildenafil was obtained by filtration. Using 2-butanone citric acid, sildenafil was converted to sildenafil citrate to give a yield of 99 to 100%. Sildenafil History of Sildenafil: Initially Viagra was developed to treat angina (heart disease). In Morriston hospital, the drug was tried on men in 1991-1992. The clinical observation showed that the drug enhance penile erection more than treating angina. Pharmaceutical company, Pfizer commercialized the drug as a treatment for erectile dysfunction. In 1996, the drug was patented and approved on 27 March 1998 by FDA. It was the first approved drug for penile erection in the United States and the sales exceed 1$ billion in 1999-2001. The Pfizers patents on this drug will expire in 2011-2013. Dosage of Viagra: Viagra could be taken once per day as a dose between 25mg to 100mg between 30 min to 4 hours before sexual intercourse. Three dosages are available in market for this drug (25-50-100) mg with a cost of 10$ per pill for all dosages. http://www.chemistrydaily.com/chemistry/Sildenafil Mode of action: Pharmacodynamics: Effects on Penile Erection: Sildenafil citrate is a selective inhibitor of phosphodiesterase-5 (PDE5) and was used for the treatment of the male erectile dysfunction (known as impotence). It is a wide spread condition that effects around 30 million patients in United States. Nitric oxide is released during sexual stimulation and permeates through corpus cavernosum membranes. Then, the enzyme guanylate cyclase is stimulated to enhance levels of cyclic guanosine monophosphate (cGMP) in the corpus cavernosum. cGMP has an effects on smooth muscle relaxation and increases blood flow lead to an erection of the penis. Level of PDE5 is high in the corpus cavernosum which hydrolyzes cGMP and leads to inactive GMP. Levels of cGMP in men with impotence are low and as a consequence PDE5 quickly hydrolyses these levels of cGMP. Now, the sildenafil acts by inhibiting the actions of PDE5 and increases the levels of cGMP which cause the erection. (6) figure involved Erection Nitric Oxide Guanylate Cyclase Sildenafil binds to PDE5 and blocks action GMP cGMP Effects on Visual Function: In patients taking sildenafil, it has been reported such visual abnormalities for example; increased blurred vision and perception of light. These effects usually happened with dose more that 100mg which is correlated to the weaker inhibition effects of sildenafil on PDE6 that regulates signal transduction pathways in the retinal receptors. (2) Cardiovascular Effects: Sidenafil has effects on blood pressures by producing transient reduction in systolic and diastolic at 1 hour after the dose. The clinical tests showed no observed effects on heart rate. Sildenafil effects are not age or dose dependent. (2) Clinical trials: The sildenafil was tested in vitro to study the inhibition of PDE5 in human blood platelets. The results showed the potency of sildenafil and it is a selective inhibitor of both c GMP PDEs. Also, a number of trials were carried on rabbit corpus cavernosum to examine the effect on the muscle. From the results, appear that sildenafil was potent in relaxing the corpus cavernosum. Furthermore, to evaluate smooth muscle relaxation, set of experiments were carried in rabbit isolated aortic rings. Sildenafil showed similar values in both denuded and endothelial intact aortic rings. (28) Side Effects from Clinical studies: Patients receiving Viagra showed similar adverse effects in all trials. Some studies showed more effects with increased dose. There were some adverse events reported when Viagra is taken in flexible dose for example; headache, rash, dizziness, diarrhea, urinary tract infection, flushing, dyspepsia and nasal congestion. http://www.rxlist.com/viagra-drug.htm Pharmacokinetics and Metabolism: The cytochrome P450 3A4 metabolizes sildenafil which changes to an active N-desmethyl metabolite that has the 50% activity of the drug for inhibiting PDE5. This metabolite has 40% plasma concentrations of sildenafil, therefore it possess 20% of the pharmacological effects of sildenafil. Terminal half-lives of sildenafil and its metabolite are 4 hours each. Sildenafil distributed into the tissues with a volume of 105 L and excreted in the feces as metabolites. In patients aged >65 years, plasma levels increased as well in patients suffered from hepatic impairment and renal impairment. (2) Viagra Plant: Pfizer Synthesis Facility, Ringaskiddy, Ireland Sildenafil citrate which is the active pharmaceutical ingredients for Viagra was manufactured by Pfizer at Ringaskiddy and the total output from Viagra sales was account for 15%. The facility covers 200 acres and composed of four production units with 500 people working there. OSP4 is the main plant at Ringaskiddy that increase production by 40% and started in 2001. Construction of the new synthetic plant (OSP4), a finished good building (FGB) and all other services were under responsibility of Project Management and Foster Wheeler. Plant started manufacturing in March 2001. Designing facility enable the OSP4 plant to produce primary bulk, batch pharmaceutical products at a reactor of 150,000 liters and six lines are at full scale. To increase service of OSP4, Pfizer was planning to build a third liquid waste incinerator. At the plant, the manufactured products are either bulk active or drug substances. For the bulk materials, they are sent in order to complete formulation and package for shipping. Production and plant facility: http://resources.schoolscience.co.uk/pfizer/viagra/viagch4pg2.html For all drugs, initially they are produced in small a mounts for the investigation and in vitro analysis. Then, quantities are increased if the carried tests are successful to meet the needs for clinical trials and patients. For the first time, production of one kg of Viagra requires a series of eleven reactions with 23 kg of reagents and 139 liters of organic wastes. All preparations are carried in a microwave designed especially for organic chemistry. For scaling up the process, it has to be more efficient and result in fewer wastes. Currently, in Viagra production only 1.5 kg of reagents are used and release just 10 liters of wastes. The company aim to minimize the waste to 6 L per kilogram produced. Now, every year the demand is 45 tones for good quality Viagra in compared to 1998 where the l kg production was enough for people demands in 10 minutes. To scale up reaction, all starting materials were available commercially and used without purification. Using a microwave oven ETHOS 1600, synthesis was performed. In standard Pyrex glassware, all reactions were carried out with a reflux condenser. The reactions were performed by a program which made up of temperature monitoring and holding steps. Purity of the final product was measured using thin-layer chromatography and molecular weight was recorded by electrospray ionization mass spectrometry. sealed vessels are used which controlled and monitored by computers to make the requir ed quantities of pure drug. Pipes are used to add the reagents into the vessel and the products are harvesting later on. Control panels are applied that allow the operator to make any required adjustments and monitoring the process. A microwave-transparent fluoroptic probe that inserted into the solutions was used to monitor the temperature of the stirred reactions mixture. To produce any pharmaceuticals, highest standards of hygiene are necessary and Laboratory should be clean and tidy. Misuse of Viagra in Asia: http://www.ergogenics.org/138.html (faked drug) According to World Health Organization (WHO), one of the most counterfeited drugs in Asia is Viagra which make a big business. Tourists in Thailand use fake Viagra which is bought over numerous pharmacies. Therefore serious health risks affected those tourists. Counterfeited medicines can impose the correct ingredients but fake package, or without active ingredients, wrong ingredients or with insufficient active ingredients. Fake Viagra made up of ingredients that enhance the bodys insulin production which can cause a danger drop in the concentrations of blood glucose. As a result lead to starving the energy of brain which in known as insulin shock syndrome. There is a widespread smuggling of fake and genuine Viagra in Thailand according to A Thai Food and Drug Administration (FDA). Unsurprisingly, Thailand is a centre for fake Viagra. Among young night-clubbers, Viagra is mixing with other party drug to increase the sexual desire. Viagra competitors: There were alternative medications prescribed for erectile dysfunction prior to the introduction of Viagra. Most of them are non-oral treatments. For example; the primary alternatives in the United States were vacuum constriction devices, penile injection therapy, penile prostheses, professional counseling and transurethral. Traditional remedies were used in other countries such as yohimbine. (4) Viagra Sales around the world: Firstly, after FDA granted approval of Viagra, it was sold in the United States. Nowadays more than fifty countries are selling Viagra in their pharmacies. On the U.S. market, one month after launch, the worth of sales was 400$ million which result from 300,000 Viagra prescriptions. Since then, 7$ per tablet was maintained by Pfizer. The average wholesale price is 8.75$ per pill in compare with other treatments such as; Caverject and Muse which priced at 20-30$ per pill. Furthermore, sales in most European countries began shortly in September 1998 after European Medicines Evaluation Agency (EMEA) granted European countries the registration for Viagra uses. In the United Kingdom, Sweden and republic of Ireland, the government Health System covers the purchases of Viagra for limited uses. Public awareness have been increased and focused on the safety issues in men taking Viagra and lead to limit the use of Viagra after reports over deaths and adverse effects that were sent to the FDA. U.S. and most other countries experienced prescription leveling off after information gained by people used the drug. Most of them were not actually suffer from erectile dysfunction. After drugs approval in the United States, Latin America launched the drug. Then, Viagra was available in a number of Asian countries, New Zealand, Australia and Canada. In 1999, Japan approved drugs uses after it accepted from other countries the clinical trials data for the first time. (4) Environmental Performance: In the medicinal route, there are a number of organic solvents included in the production of 1000 kg of drug substance and the volume of these solvents equal to 125,000 liters. These solvents are reduced to 13,500 liters in the commercial route. The solvents required in both routes are illustrated in figure 1. Organic wastes from medicinal route Organic wastes from commercial route For environmental assessment, the reduction of some solvents for example; chlorinated solvents and highly volatile solvents such as; methyl chloride, methanol, acetone and diethyl ether. Elimination of these solvents results in elimination of atmospheric emissions. T-butanol that has been used in the commercial route is completely water soluble and is difficult for reuse. In order to improve environmental performance, t-buanol is replaced by another solvent to facilitate recovery. The optimized process was developed in Ringaskiddy and will be used in the production plant which will give 4 l kg-1 of the final optimized solvent usage. (5) http://en.wikipedia.org/wiki/Atom_economy Atom economy is the efficiency of conversion all reactants in a chemical process in a way of all atoms involved and no atoms are wasted. All starting materials equal to generated process, this represent an important concept in green chemistry. Reaction mass efficiency is a measure for the effect of yield and an increase of used reagents. Between 1994 and 1997 where the new commercial route was introduced, there was an improvement in the reaction mass efficiency and chemical yields. In contrast, the atom economy remained constants over time. Comparisons of these parameters between 1994 and 1997 is shown in figure Fig. Atom economy, chemical yield and RME at 1994, 1997 and the future target in the sildenafil citrate process. The aqueous and organic wastes are actually measured and from modeling process the atmospheric emissions are estimated. There was a large reduction in the aqueous waste when the commercial route was introduced into the production. Moreover, upon introduction of the commercial route, again there was a noticeable reduction in the organic wastes between 1994 and 1997. Due to the impact of introducing solvent recovery operations and reuse in the manufacturing process, a further large reduction occurred after 1997. These decreasing reflect the importance of eliminating wastes and controlling route selection. For the vapor emissions, there have been smaller diminish in the released amount. In addition, it was found there was 35% decrease in the estimated energy used between 1994 and 1997. There are two reasons behind smaller reduction in the vapor emissions and the used energy; firstly, in order to maximize the yield, there is a significant level of solvents stripping performed in the comm ercial process. Secondary, the chemistry team actively managed and followed such parameters for instance; organic, aqueous wastes and yield. On the other hand, they calculated retrospectively the emissions and energy. (5) Figure shows the comparisons between these wastes at various times. The E-factor is the total kilos of wastes per kilogram of product. In commercial route of Viagra production, the E-factor is 6 kg kg-1 which is less than the industry standard of (25-100) (6) Low volumes of the complicated chemical products and the E-factor of the commercial route for Viagra production generate fewer wastes per year. For all of the environmental awareness taken by Pfizer for the sildenafil citrate process, UK Award was granted to this company in 2003. (2) Patents: According to the U.S. Patent and Trademark Office, patent for Viagra by Pfizer will expire on March 27, 2012. Then, a cheap generic version of the blockbuster erectile dysfunction drug will be sold by any drug company. This will allow more competition between Pfizers Viagra and the new generic versions and more options with cheaper prices for patients. Pfizer has three options to stay in the Viagras market. Firstly, it can market itself as the main company for selling Viagra, taking into account there are over 25 million men used its version and they donà ¢Ã¢â€š ¬Ã¢â€ž ¢t like to change. Secondary, it can apply for Viagra with FDA for OTC (over-the-counter). Finally, while producing an upgraded version of Viagra which will continue holding value of the patented product, it can license the original recipe to Viagra to other companies. http://www.accessrx.com/research/viagra-patent-expires.htm Alternative Routes to Sildenafil: There are more than 15 different routes have been reported in the chemical and patent literature to sildenafil. Pfizer examined two main alternatives during the development process either by synthesis sildenafil through the aldehyde 11 to produce dihydrosildenafil 12 then oxidize the product or by the halo derivatives for example 13 or 14. 52 % of sildenafil yielded from condensation between aldehyde and aminopyrazole to give dihydrosildenafil by adding an azeotropic distillation to remove the water by product. The yield can be increased to 95% as shown by some workers. (PATENT 22918) Aldehyde Amine Dihydrosildenafil Sildenafil Oxidation of dihydrosildenafil either by using sodium hydrogen sulphite (NaHSO3) or using small quantity of trifluoroacetic acid and Pd/C at high temperature generated a good yield of drug (patent WO 01-98303). Dihydrosildenafil Sildenafil Combination between a nucleophilic displacement reaction that uses ethanol as a solvent and a hindered alkoxide (KOBU) or ethoxide (EtOH) as a base and the cyclization reaction which uses a compound like halo derivatives is another potential synthesis for sildenafil. The combination reaction works for both cyclisation compounds, but by using a compound where (x= F) the yield from combination is 100%. The use of the chloro-series compound (x=cl) in the cyclisation reaction is better because of 2-chlorobenzoic acid is cheaper than 2-ethoxybenzoic acid. (Patent number EP 0994 115) Figure (13, 14, synthesis) Halo Derivatives X= Cl X= Fe, yield= 100% In the end, all of these alternative routes were put on hold due to the high efficiency of the commercial route and the time pressures of the development program. (6) (3) In the WO Patent (98284), amidine 10 or iminoether 11 can be used in order to build pyrimidine ring (sildenafil). By a Pinner reaction, the iminoether is made from the nitrile. Amidine is made by reaction of the nitrile with chloromethylaluminium amide which is synthesized from trimethyl aluminium (Me3Al) and ammonium chloride (NH4Cl) Nitrile Amidine Iminoether Sildenafil Intermediate 14 was prepared from reaction of the acid intermediate 13 with thionyl chloride (SOCl2) to give the lactone which then can be reacted with ammonia (NH3) and (EtOH) to produce the pyrazolopyrimidinone which is away to make sildenafil. Acid intermediate Lactone Sildenafil (Patent EP 1 002 798) sildenafil synthesis from intermediate (6), can be done by chlorosulphonate the intermediate 16 and before cyclisation the intermediate convert to the sulphonamide6. Sildenafil There are many patents activities in producing nonconvergent synthesis of sildinafil. Workers at the Torcan Company reduced Carbamate by (LiALH4) to sildenafil in ayield of 61%. ( Patent 2 235 642). Carbamate Sildenafil Also, sildenafil was synthesized from pyrazolopyrimidinone and the sulphamoyl chlorid (which is prepared by SO2Cl2 and N-methylpiperazine reaction) using Friedel-Craft reaction which requires ALCl3 by workers at the India Orchid company. (Patent EP 1 077 214) Pyrazolopyrimidine and sulphamoyl chloride Sildenafil Furthermore, workers in Cipla Company have synthesized sildenafil by double methylation of this intermediate by using formic acid and formaldehyde (CH2O) and (HCO2H) as the final step. (Patent WO Patent 01/ 19827) Sildenafil

Factors Affecting Food Selection Essay

1. Introduction The purpose of this report is to analyse the 4 main types factors that affect the food selection of adolescents and how each of these factors affect their diets. As a result of examining various internet websites and books about this topic, this report describes the 4 types of factors that affect food selection and the factors that influence the food selection of teenagers the most. Consuming food is vital for adolescents since they aren’t fully developed yet, and what they eat is influenced by various factors. The main types of factors are psychological, physiological, social, and economic factors, and each of them influence what choices people make when it comes to food. Over the past 20 years, teenagers have adopted the habit of consuming a lot of junk food, due to the influence of many economic, psychological, physiological and social factors. As time goes on, the factors that affect the food choices of adolescents may change. Overview of social factors Social factors that affect food selection refer to the cultures and societies that adolescents live in, along with how the interaction with other people greatly influence the food choices that they make. One of the reasons why social factors has a significant influence on adolescents is because their attitudes and habits relating to food usually develop through the interaction with their peers, friends and families. Social factors that have a great impact on the food selection of adolescents are the media, and their peers. Read more:Â  Factors that influence child development essay 2.1 Peer Influences A peer is a person that has the same social status, and is around the same age as another person. The influence of peers is the greatest in adolescence. the reason for this is because like fashion, trends come and go in the food industry. For adolescents, being ‘cool’ and being accepted among their peers is vital, so they usually follow the food trends that the majority of the group follow for that sake. Although, this causes them to disregard their parent’s influence on what they should and should not eat. In today’s society, teenagers are influenced by their peers to eat at popular fast food outlets such as Mcdonalds, since it’s a popular food trend among them. This affects them in a negative way since the food that is sold at these outlets can have poor nutritional values. This causes an increase in diet related diseases in teenagers such as type 2 diabetes, and according to the Department of Health and Aging, type 2 diabetes i s becoming more common in younger age groups. 2.2 Media In affluent societies, the media plays a significant role in food selection for adolescents. This is because they are exposed to the thousands of food advertisements on a daily basis. There are advertisements nearly everywhere they go, such as on television, the internet, school buses, radios, and magazines, so adolescents will be tempted to eat the product that is being advertised. The negative effect of these advertisements is that they are advertising food that is high in sugar, salt, and fat so they aren’t ideal for meeting their nutritional requirements. The media is one of the many factors responsible for the unhealthy lifestyles in teenagers and according to the Department of Health and Aging, 25% of children and adolescents were either overweight or obese in 2007-08, and to this day, this percentage has increased. 2.3 Education Education about food and nutrients is essential for adolescents, since it helps them to become more knowledgeable and educated about their options when it comes to food selection and the nutritional requirements of their age group. Also, teenagers that are informed about this will most likely make better and wiser food choices than those who don’t, although this all depends on whether the person is able to apply the knowledge into their everyday lives. Furthermore, adolescents that have the knowledge and skills to prepare their own food are also more likely to make better and wiser food choices. The reason for this is because making a meal from scratch can prevent buying prepared meals from fast food outlets, and home-cooked meals have a higher nutritional value than preprepared meals. Overview of psychological factors Psychological factors are linked with an individual’s emotions, and their thoughts. The psychological factors that affect a person’s food selection vary from individual to individual, since they are based on their lifestyle and childhood. They are also hard to describe and some factors even have a continuous influence on an individual (E.g. Beliefs, values.) while others can change each day. (E.g. Attitudes, self esteem). Psychological factors that are significant in the food selection of adolescents are beliefs, experiences and self-concept. 3.1 Self concept Self concept is how individuals feel about themselves (Also known as self esteem) and the way the see their body image. Self concept can change over time, or even a few times a day. E.g. A compliment can boost your self esteem. Over the past few years, people as young as 11 have started to become dissatisfied with their body image, especially females. The reason for this is because the media has presented teenagers with the beautiful, and talented people who have the ‘ideal’ body type, which has caused a decrease in self esteem, and the dissatisfaction with their body image. As a result of this, many teenagers have tried to get the ‘ideal’ body image by dieting, and the Department of Education and Child Development stated that ‘68% of 15 year old females are on a diet, of these, 8% are severely dieting’. Self concept is a reason why people diet, and it has a huge impact on food selection since it can influence teenagers to eat f ood that have a high nutritional values. Despite this, it can also lead to them eating next to nothing, which can potentially lead to life threatening eating disorders such as anorexia nervosa. 3.2 Beliefs A belief is an opinion that isn’t based on scientific proof, and they are often based on religion and cultural heritage. Many religious communities have placed restrictions on what their people can eat. (E.g. Hindu’s cannot eat beef because cows are sacred in their religion.) The reason why there are restrictions is because in the past, people believed that it would protect others from diseases, and poor hygiene. Beliefs are very significant, since they can influence eating habits. The reason for this is because adolescents usually follow the food beliefs of their own parents, so the food that they choose to eat would depend on that. For example, a teenager will most likely be a vegetarian if their parents are vegetarian. 3.3 Emotions Even though it may not seem like it, emotions play an important role in food selection, especially during adolescence. The strongest desire for food happens when people are emotionally sensitive, and most are not even aware of it. Emotional eating is when people consume food as a way to deal with their emotions, and teenagers usually use it as a way to suppress negative emotions, such as grief, sadness, anger, and stress. It can be caused when they go through depressing events in life, such as the loss of a loved one, boyfriend/girlfriend breakups, divorce of parents etc. When this happens, ‘comfort foods’ are consumed, which are foods that are usually high in fat, sugar, salt (For example, ice-cream, chocolate, candy, potato chips) and are generally not good for the health of teenagers if it’s constantly happening. Overview of physiological factors Physiological factors affect the body’s craving (appetite), and need for food (hunger). The body needs a certain amount of nutrients from food in order for it to function properly, and to be healthy. The amount of nutrients required vary from person to person, and they are based on their age, gender, build, activity level and health. Even though teenagers should eat according to their nutritional requirements because they are still developing. Over the past few years, they usually eat according to what satisfies them. 4.1 Nutritional Requirements Nutritional requirements are the amount of minerals/vitamins an individual has to take in order to have a healthy lifestyle. The nutritional requirements of an individual depends on their life stage (Infant, child, adolescent, etc.), since each stage requires a different amount of nutrients. As adolescents, they are still developing so they need to have a higher calcium and protein intake (for bone and tissue growth), and carbohydrates (For energy). Gender plays in an important role in the nutritional requirements of adolescents. Females start to go through their menstrual period at this stage in life, so they require more iron to counter the blood loss during that time. They also need folate, because it decrease the chance of brain and spinal birth defects by 50-70% if they get pregnant at a later stage. Males on the other hand, they require more zinc in order to protect their prostate gland and more protein to maintain their muscle tissues, since they h ave a higher proportion of muscle tissue than females. 4.2 Aroma and Taste Aroma and taste are closely related. Plenty of food gives off a scent that can be tasted before the food is actually eaten.The taste and aroma of food is one of the most important factors when it comes to food selection. The reason for this is because it’s what determines what food is appetising, and what isn’t. For example, people wouldn’t eat something that has a bad odour. Adolescents tend to `choose the food they eat based on it’s taste, regardless of nutritional value and since junk food tends to be tastier than healthy food, the majority of teenagers eat junk on a daily basis. 4.3 Allergies/Food intolerance A food allergy is when the immune system reacts to a certain type of food and rejects it, where as a food intolerance is the inability to digest a certain type of food. If a teenager has a food allergy or intolerance, then it would affect their food choices, since they would have to ensure that the food they consume doesn’t contain the food that they’re allergic/intolerant to. When a person has If they were to consume food that they are allergic to, they would suffer from symptoms such as diarrhea, eczema,and asthma. Similarly, if a person were to consume food that they were intolerant to, it would cause symptoms such as migraines, breathing problems and diarrhea. 5. Overview of economic factors Economic factors relate to the food market and the costs. It is significant to food selection since the type of food that a person eats usually depends the cost, the market and the resources that are available to the person. Economic factors also determines whether people are able to eat the food they want, or the only the food that they can afford. For adolescents, they only can eat what their parents are able to afford and what they can afford while they’re not at home. 5.1 Cost of Food The cost of food is an important factor to consider. As an adolescent, what they eat at home relies on the income of their parents, since that determines the quality and type of the food that is bought. Also, teenagers usually don’t have a lot of money to spend on food while they’re out with friends. As a result of this, they usually have a habit of constantly eating at fast food outlets such as Mcdonalds because the food is cheap. Although this is convenient, it’s a bad habit because if junk food is constantly being consumed, they’re not meeting their nutritional requirements and can cause diet related diseases later on. It is estimated that roughly 9 in 10 teenagers eat junk food everyday. 6. Conclusion There are various factors that affect the food selection of adolescents. These factors are divided into four categories- Social, economic, psychological and physiological. They all affect adolescents in various ways, and are some affect them negatively (E.g. the media), by influencing them to take on bad eating habits. Despite this, there are also that affect them positively (E.g. Education) by encouraging them to have healthy eating habits.

Challenges Through Siddhartha’s Path Essay

Siddhartha is a character in which he searches to find the right way of life through many different paths, which I will be relating myself with. With his decisions, he finds a lot of experiences and varies through the way of life of others. Siddhartha’s life as we know it, is very amusing to others, but not as complete as he would want it to be. Siddhartha’s intelligence, pure spirit, and ability to recognize Atman, gives him a sense of security toward the other Brahmins. His friend Govinda, loves Siddhartha’s every move and gesture which he often tends to make. While he decides to follow him, they go together to become Semanas, but then separate to find their own destiny. Siddhartha decides to continue onto his own path and start a new life, but realizes that he is losing not only his best friend but chooses to start a new life. The path of being â€Å"enlightened† and the journey to be one with God is according to how much you desire this quest. Being one with God, can either take your whole life or just a portion, which you think is enough to think and believe you are one with God. I don’t believe he asks for any favors, or requirements to be where you would like to be. To be able to choose is one of the most powerful abilities that a person has. When you choose, you show that you will do what is desired and wanted by yourself. To tell the truth, I don’t think I’ve ever tried to enlighten myself in any way. If I choose to, I think that I would want to meditate and free myself of all stress, anger, impatience, etc. To be able to feel free and pure of all negativeness, would be as if I were one with God because I know that he doesn’t want me or anybody in a world of anger or hatred. To have a world full with peace and harmony would be my Enlightenment, my stage in life where I have achieved to be one with God. During Siddhartha’s exploration, he views and thinks of other people as being unique and dissimilar from his own way of life. As he walks into other cultures, he begins to realize what he must do to be one with his own Self. Although, he thinks that these people know little about what the true meaning of life really is, he also begins to absorb and become one of them.  Throughout his life, he meets a girl named Kamala, which he chooses that she is the one to teach him about love. He also learns an important lesson and allows him to realize that he can’t love Kamala. A dream occurs to Siddhartha, which is a bird in a golden cage dies. This means that his inner voice and all the good inside of him had disappeared, due to the new life he has adopted to and was now living in. He must run away and regain what he has forgotten as a little boy. After running away, Siddhartha has an urge to kill himself, by throwing himself into the river. By changing his ways of life and searching for his own Self through other cultures, made him realize that his life was now going down the wrong path. In the world today, due to the wars and battles that people all around have begun, I have questioned if this world would ever be able to be one with God. I have never once doubted my belief in God. On Sunday morning, church is available to those Catholics who are willing to go into the house of God and pray for those who you have wished to pray for. I never doubted that God wouldn’t be listening when I needed him by my side. He is everybody’s angel, all you have to do is listen to what the Lord tells to you. I don’t believe that by going to church, you have earned the right to go to heaven. I believe that any person that stays at home and prays to our Lord and to the Rosary, has earned that same right as the other people have. We have the right to choose whether or not we are going to be shooting stars or falling leaves. When your at home and you are afraid, or you’re alone with no one to turn to, I have the instinct to say a little prayer to God, so that he is aware how I feel. I don’t think that there is any other feeling, than to go to Confession and tell the priest what sins you have committed, but then still to know that those sins are now forgiven by the Lord our God. He has given us the most beautiful gift, which is life. I just think that sometimes we abuse that gift, and people need to step back and look at what we have caused. God has given us, something in which no one else could, so my beliefs in God grow everyday, and hope for the day when I can feel what my grandmother is feeling with God. Siddhartha is a character which has gone through many paths to find and be at one with his own Self. As he travels through the different cultures and worlds of other Human Beings, he will begin to realize what he must do to get where he would like to be.

Causes of Blindness Free Essay Example, 2000 words

There are many causes of blindness, but severe distinguishing features have been identified as leading factors that contribute to an individual either being born blind or losing their vision later in life. The most commonly attributed factor leading to blindness are diabetes, macular degeneration, traumatic injuries to the eyes, infection, glaucoma, and a lack of access to proper glasses or correction vision equipment. There are some other factors that lead to blindness, although they are much less common in occurrence. These include vitamin A deficiency, retinopathy of prematurity, vascular disease that affects the retina or optic nerve of the eye including having a stroke, ocular inflammatory disease, retinitis pigmentosa, primary or secondary malignancies of the eye, congenital abnormalities, hereditary diseases of the eye, and some type of chemical poisoning from toxic agents, including methanol. When an individual suffers temporary blindness, it is important to note that the causes are often different from those involved in individuals that develop permanent blindness (Gyles, 2002). In diagnosing this particular disability, an examination of all parts of the eye will usually be conducted by an ophthalmologist to determine the extent of the blindness. Globally, individuals who are blind or are visually impaired are defined as such by they're unable to see properly, or who experience great difficulty when attempting to see. Individuals who tend to lose their vision in a rapid fashion, as opposed to over a number of years, are typically more symptomatic in terms of their vision loss. It is important to remember that the actual treatment of blindness is directly related to the cause of the disability itself, which makes it critical for an individual to work with his or her doctor to determine what exactly happened to cause the vision loss in order to receive the most direct and effective and effective treatment options (Prescott, 2011). We will write a custom essay sample on Causes of Blindness or any topic specifically for you Only $17.96 $11.86/pageorder now