Oct 12, 2020 in Medicine Essay
Viagra Medicine Essay Sample

History and Epidemiology

Viagra is a medication that was initially created by Pfizer pharmaceutical company as a medication for the persons suffering from hypertension and ischemic cardiovascular disease in 1989 in England. In 1991, its inventors David Brown and Nicholas Terrent discovered that the chemical compound belonging to the pyrazolopyrimidinone class was useful in the management of heart illnesses, such as angina pectoris. This let Dr. Nicholas Terrett obtain a patent for sildenafil citrate trademarked Viagra as a heart medication, and some medical experts refer to him as the father of Viagra (Brooker 68). Nonetheless, sildenafil citrate as a heart medication failed to show promises and the investigation on the drug was stopped in 1992. In 1994, Peter Ellis and Nicholas Terrent discovered during trial studies that sildenafil citrate as a heart medication increased blood flow to the penis area, thus, permitting men with erectile dysfunction to get back their ability to get an erection. The experts discovered that the medication acted by augmenting the smooth muscle through relaxant effects of nitric oxide (NO), a substance that is usually released in response to sexual stimulation. The relaxation of the smooth muscles stimulates an increased blood flow to the penis leading to an instant erection when combined with little excitement (Brooker 56).

The first phase of clinical investigation revealed that the drug had little impact on angina pectoris, but it had a huge potential to induce significant penis erections. As a result, Pfizer resolved to put the drug on the market as an anti-impotence medication rather than a cardiac one. In 1996, the drug was patented, and the clinical investigation found sildenafil citrate to be so effective that the United States Food and Drug Administration approved its use only six months after submission. Besides effectiveness, there were found no significant side effects resulting from the use of the drug (Brooker 45). This made Viagra become the first approved non-surgical treatment for male impotence or erectile dysfunction that did not need to be injected or inserted into the penis to achieve erection.

Sildenafil citrate is a highly selective inhibitor of cyclic guanosine monophosphate specific phosphodiesterase type 5. The United States Food and Drug Administration (FDA) has revealed that more than 890 men with a mean age of 64 years have been confirmed dead after taking sildenafil citrate within a period in which more than ten million prescriptions have been dispensed. Furthermore, US FDA reported significantly frequent cases of sudden cardiac death in men with erectile dysfunction after taking sildenafil citrate, especially from arrhythmia (Loe 98). As a consequence, such report have raised concern that sildenafil citrate may essentially increase the risk associated with cardiovascular diseases. According to extensive data from FDA, sildenafil citrate has been found to pose minimal cardiovascular dangers to healthy people who decide to use this medication. Nonetheless, precautions do not apply to individuals with cardiovascular illness (Loe 56). The only absolute contraindication for sildenafil citrate is the concurrent use of nitrates.

Pharmacology

Sildenafil citrate is quickly absorbed after its consumption, with a total bioavailability of approximately 40 percent. The medical process of erection normally includes the production of nitric oxide (NO) during sexual excitement and stimulation. Nitric oxides activate the enzyme guanylate cyclase that leads to rising of the guanosine levels in the consumers blood. This effect leads to relaxation of the penis muscles that stimulates an increased blood flow (Loe 76). Nonetheless, sildenafil has no direct impact on the secluded corpus cavernosum but improves the impact of NO through restriction of phosphodiesterase type 5 that is responsible for deprivation of the guanosine monophosphate. When sensual stimulations prompt the production of nitric oxide, restriction of the phosphodiesterase type 5 by the sildenafil leads to raised levels of guanosine monophosphate in the corpus cavernosum. Consequently, this results in smooth muscle relaxation and increased flow of blood to the corpus cavernosum (Loe 112). When used in recommended doses, sildenafil has a positive effect on the lack of the sexual excitement. Sildenafil citrate is eliminated from the body through hepatic metabolism and it is transformed to an active metabolite with properties parallel to the parent, sildenafil. Both the metabolite and the sildenafil have a terminal half-life of four hours. Although sildenafil is quickly absorbed in the human system, maximum blood concentration is reached within 40 to 120 minutes after the oral consumption of the drug (Loe 116). When taken with the meal with high fat level, the absorption rate in the system is usually lowered significantly. Sildenafil and its metabolites are usually bound to the blood protein. The protein binding does not depend on the total drug concentration. Based on a study conducted on healthy volunteers, sildenafil was found in semen 90 minutes after consumption. After administration of the medication either intravenously or orally, sildenafil is removed from the body as a metabolite in the feces and in a slighter amount in the urine. However, elderly aged 56 years and above showed lowered clearance of sildenafil, with plasma concentration reaching 40 percent higher than those observed in healthy volunteers of 19-44 years. Since sildenafils breakdown is mainly facilitated by the cytochrome isoforms, inhibition of these Iso-enzymes decreases sildenafils clearance. It has been discovered to induce postural hypertension when linked with nitrates. It is simply because sildenafil initiates the action of nitric oxide (Loe 54). Therefore, sildenafil has to be stringently avoided by the patients under nitrate rehabilitation.

Manufacturing and Marketing of Viagra

Manufacturing

Viagra is manufactured in Pfizers facility in Cork, Ireland. The chemical process of manufacturing Viagra is very complex. The manufacturing involves development of smaller molecules that are gradually built and connected together to produce the Viagra molecule. This requires many stages of synthesis and purification (Li 67). The manufacturing process of Viagra entails a number of processes that include screening, blending, roller compaction, lubrication and compression. A clear coating of blue Opadry is applied to the tablet.

Adequate process controls are offered in order to ensure that tablet quality specifications are met. However, prior to compression, the potency and the uniformity of the lubricated blend are determined through the use of specific HPLC test. Quality control evaluation of completed drugs is adequately authenticated in accordance with the set of requirements and quantitative determination of active ingredient (Li 115). Moreover, standardization test relating to water content and mass variation is conducted in accordance with the set specifications. This makes sildenafil film coated tablet be conventionally formulated and manufactured in accordance with the set pharmaceutical technological standards. Furthermore, pharmaceutical profile is usually well-documented during the entire manufacturing process and is transferred together with the product to the consumer.

Marketing

Although sildenafil is only accessible under medical prescription from a qualified medical practitioner, the drug is extensively marketed on TV and the Internet. It has also been supported by such famous characters as Pele, a prominent footballer, and Bob Dole, a US senator (Li 118). Many websites on the Internet provide Viagra for sale after a simple online consultation that entails filling in a simple web questionnaire. In 2000, the sale of Viagra accounted for more than 92 percent of the global market. In 2007, the global market share for Viagra was approximately 50 percent due to entry of other brands, such as Levitra and Cialis alongside other counterfeits. In February 2007, Boots, UK pharmacy chain, made an effort to stop over-the-counter sales of Viagra in England. Men between 35 and 64 years old were qualified to purchase 4 tablets but only after consultation with a chemist. In 2013, Pfizer, the manufacturer of Viagra, started to offer the drug directly to the consumer through its website.

Dosage, Expected Effects, Side Effects and Potential for Overdose

Dosage

For most clients, the commended amount is 50 mg, consumed roughly one hour before sexual action. It is worth noting that the Viagra tablets are accessible in 25 mg, 50 and 100 mg packages. However, Viagra may also be taken in a range of 20 minutes and four hours before sexual action. Depending on the effect, the dosage may be raised to an optimum measure of 100 mg or reduced to 25 mg administered daily (Botz-Bornstein 45). The maximum permitted dosage is once per day. Persons aged 65 years and over, those with liver problems or under cytochrome inhibitor should start with 25 mg. For individuals taking ritonavir, the doseshould not exceed 25 mg daily in any 48 hours period.

Expected Effects

Consumption of Viagra leads to deprivation of phosphodiesterase in the cavernous body of the penis. Nitric oxide produced in the cavernous part of the penis combines with the guanylate cyclase receptors, which leads to the rise in guanosine monophosphate levels (Botz-Bornstein 98). This consequently stimulates slackening of the smooth muscles of the helicine arteries. The slackening of the smooth muscles prompts vasodilation that increases the blood movement to the blood vessels in the spongy tissues of the penis, which leads to an erection. Besides, the consumption of more than 100 mg per day may cause the development of various health problems, such as headache and flushing.

Side Effects

The use of Viagra has been found to prompt serious side effects in the consumers. The Viagra property of expanding the blood vessels usually results in a reduction of its users blood pressure. However, for individuals with underlying heart ailments, it is usually more subtle due to the vasodilation impact of the Viagra. Persons with left ventricular outflow obstruction and those with severely impaired autonomic control of blood vessel have been found prone to adverse side effects of Viagra (Botz-Bornstein 79). Moreover, some users experience pain due to prolonged erection lasting for more than 4 hours. If such condition is left untreated, it eventually leads to damage of the penis muscle that may cause permanent loss of potency. Other side effect is impaired vision or even its loss, especially after consumption of high Viagra dose. Besides, sexual activity exerts considerable strain on the heart, especially in individuals with heart problems. Some individuals may also experience pain in the jaw/arm/chest. Moreover, serious allergic reaction sometimes occurs, though rather rarely (Botz-Bornstein 117).

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In addition, it is common for an individual to experience mild headache, congested nasal passage, dyspepsia and flushing as a result of Viagra intake. The users also experience changes in color vision or blurred vision that encompasses photophobia. Furthermore, some Viagra users complain of seeing objected as being tinted blue, a condition known as Cyanopsia. A number of clinic investigations have connected Viagra with occurrence of ischemic optic neuropathy. Severe and mild myocardial infarction has also been noted, especially in individuals taking 100 mg of the medication (Botz-Bornstein 120). The use of Viagra among the aged population has been associated with the occurrence of shock, chest pain, edema and abdominal pain. Other side effects include occurrence of digestive problem, such as dry mouth, stomatitis, gastroenteritis and vomiting. It is essential to note that some side effects have not been concluded to be related to Viagra since such effects have been reported days after the last intake.

Potential for Overdose

Consumption of more than 100 mg of Viagra has been found to be far above the recommended dosage. However, studies indicate that individuals who took a single dose of 800 mg reported similar adverse effects as those who took lower medication (Brooker 118). Also, such effects vary significantly depending on the bodys physiological condition of the user. Too much Viagra can lead to chest pain, irregular heartbeat, light-headedness and nausea. Apart from the above symptoms, consumption of more than recommended dosage increases the risk of serious adverse effects, such as prolonged, painful erections, low blood pressure and life-threatening cardiovascular issues that could eventually lead to death (Brooker 186).

Specific Treatment Used during Rehabilitation

Viagra is not habit-forming, which means that men taking the medication are not usually under the threat of developing addiction to the medication. However, in some individuals, a serious complication develops as a result of drug use (Loe 154). Priapism is a condition in which individual experiences prolonged erection, mostly of more than four hours. Treatment of this condition is usually provided at emergency department. For priapism patient, the first step is usually managed through blood exchange transfusion. In other patients, orally administered pseudoephedrine is usually effective since it exerts a constriction effect on the smooth muscle of the corpus cavernosum. In its turn, this facilitates venous outflow (Loe 157).

The sympathomimetic medication that belongs to the amphetamine class has been used to induce erectile dysfunctions. Therefore, such medication is important in managing Viagra induced priapism because the main goal of it is to aspirate the blood from the smooth muscles of the penis. In the instance where such method is found to be ineffective, intracavernosal injection containing phenylephrine is offered (Loe 172). Nonetheless, such complex medical procedures are only performed by trained medical professionals while the patient is put under constant hemodynamic to monitor progress since the medicine has the potential to lead to severe hypertension, bradycardia, arrhythmia or tachycardia.

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