Vigorex 50 mg

Description

Indications
Vigorex is used for the treatment of erectile dysfunction in men, which is the inability to achieve or maintain a penile erection sufficient for satisfactory sexual performance. For Vigorex to be effective, sexual stimulation is required. In addition, Vigorex is also indicated for managing pulmonary arterial hypertension.
Use as prescribed by a registered medical practitioner.

Description
Vigorex is a selective, reversible inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). During sexual stimulation, the body releases nitric oxide locally, which then inhibits PDE5 and increases cGMP levels in the corpus cavernosum. This process causes smooth muscle relaxation and allows for increased blood flow into the penile tissues, leading to an erection. It is important to note that Vigorex will only work in the presence of sexual stimulation.

Pharmacology

• Mechanism of Action: The physiological process of achieving an erection involves the release of nitric oxide (NO) in the corpus cavernosum during sexual activity. NO activates the enzyme guanylate cyclase, increasing the levels of cGMP. This, in turn, leads to the relaxation of smooth muscles in the corpus cavernosum, permitting the inflow of blood and resulting in an erection. Sildenafil does not directly relax the human corpus cavernosum but enhances the action of NO by inhibiting PDE5, which is responsible for breaking down cGMP in the corpus cavernosum. Sildenafil’s effect is only active during sexual stimulation, increasing cGMP levels and causing smooth muscle relaxation and blood flow into the corpus cavernosum.
• Pharmacokinetics and Metabolism: Sildenafil is absorbed quickly after oral administration with an average bioavailability of 41% (range 25-63%). It is primarily metabolized by the liver through cytochrome P450 3A4 and converted into an active metabolite that has similar properties to the parent drug. Both Sildenafil and its metabolite have a terminal half-life of around 4 hours.
• Absorption and Distribution: Sildenafil is rapidly absorbed with maximum plasma concentrations reached between 30 to 120 minutes (median 60 minutes) after oral dosing on an empty stomach. The absorption rate may be slower if taken with a high-fat meal.
• Metabolism and Excretion: Sildenafil is processed by liver enzymes and primarily excreted through feces (about 80%) and to a smaller extent in urine (about 13%).
• Pharmacokinetics in Special Populations: In elderly individuals (65 years or older), the clearance of Sildenafil is slower, resulting in approximately 84% to 107% higher plasma levels compared to younger individuals.

Dosage & Administration

• Erectile Dysfunction: For most patients, the recommended dose is 50 mg, taken approximately one hour before sexual activity. The dose can be adjusted between 25 mg and 100 mg based on effectiveness and tolerance. The maximum recommended dosing frequency is once per day.
• Pulmonary Arterial Hypertension: The suggested dose is 20 mg, taken three times a day, with a 4-6 hour gap between doses, with or without food.

Certain factors, such as age over 65, hepatic impairment, or renal impairment, may increase Sildenafil’s plasma levels. In these cases, a starting dose of 25 mg should be considered. Sildenafil should not be used with nitrates as this may result in a dangerous drop in blood pressure. Additionally, patients on alpha-blockers should start with the lowest dose of Sildenafil.

Interaction
Vigorex is mainly metabolized by the cytochrome P450 isoforms 3A4 and 2C9. Inhibitors of these enzymes may reduce Vigorex clearance, while inducers may increase it. Co-administration with certain drugs, such as cimetidine, erythromycin, or ritonavir, may significantly increase Vigorex levels in the bloodstream. However, using Vigorex with strong enzyme inducers such as rifampin may reduce its effectiveness.

Contraindications
Vigorex is contraindicated in patients with a hypersensitivity to any of its components. It should not be used by individuals who are taking organic nitrates regularly or intermittently due to the risk of severe hypotension.

Side Effects
Potential side effects of Vigorex include:

• Body as a whole: Edema, allergic reactions, pain, chills, accidental injuries, abdominal discomfort.
• Cardiovascular: Angina, hypotension, heart attack, arrhythmias, palpitations, myocardial ischemia.
• Nervous system: Headaches, dizziness, visual disturbances, insomnia, anxiety.
• Digestive: Nausea, indigestion, dry mouth, abnormal liver function tests.
• Urogenital: Erection abnormalities, urinary incontinence, breast enlargement.
• Skin: Rash, dermatitis, itching.
• Special senses: Temporary vision loss, tinnitus, eye discomfort.

More serious cardiovascular events, such as heart attack or stroke, have been reported in association with Vigorex, often in individuals with pre-existing heart conditions.

Pregnancy & Lactation
Vigorex is not recommended for use by women, and there are no adequate studies in pregnant women. It is classified as a Category B drug in pregnancy, with no evidence of teratogenic effects in animal studies.

Precautions & Warnings

• Alpha-Blockers and PDE5 Inhibitors: Vigorex should be used with caution when combined with alpha-blockers, as both can lower blood pressure. Ensure patients are stable on alpha-blocker therapy before starting Vigorex at a low dose.
• Cardiovascular Risk: Men with cardiovascular conditions should avoid Vigorex if sexual activity is not advisable.
• Anatomical Issues: Caution is needed in patients with penile anatomical deformities or conditions predisposing to priapism.

Overdose Effects
In case of an overdose, standard supportive care should be provided. Vigorex is highly protein-bound, so renal dialysis is unlikely to accelerate its clearance.

Storage Conditions
Store in a cool, dry place, away from direct sunlight and heat. Keep out of the reach of children.