Additional information
| Clinical Pharmacology | Pharmacodynamics and Mechanism of Action: Sildenafil is a potent and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5) in the corpus cavernosum, where PDE5 is responsible for the degradation of cGMP. Sildenafil has a peripheral site of action on erections. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum but potently enhances the relaxant effect of NO on this tissue. When the NO/cGMP pathway is activated, as occurs with sexual stimulation, inhibition of PDE5 by sildenafil results in increased corpus cavernosum levels of cGMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum. Accordingly, erectile function is improved. |
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| Pharmacokinetics | Absorption: Sildenafil is rapidly absorbed. Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When sildenafil is taken with a high-fat meal, the rate of absorption is reduced, with a mean delay in Tmax of 60 minutes and a mean reduction in Cmax of 29%. Distribution: The mean steady state volume of distribution for sildenafil is 105 L, indicating distribution into the tissues. Sildenafil and its major circulating N-dimethyl metabolite are both approximately 96% bound to plasma proteins. Metabolism: Sildenafil is primarily metabolized by CYP3A4 and CYP2C9, with its major metabolite having similar PDE5 selectivity but approximately 50% of the parent drug's potency. This metabolite accounts for about 20% of sildenafil's pharmacological effects. Excretion: After either oral or intravenous administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of the administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose). Before You Start 5- Star Tablets: Tell your doctor if you: -Have a history of heart problems, including heart attack, irregular heartbeat, angina, chest pain, aortic valve narrowing, or heart failure. -Have had Heart surgery within the last 6 months. -Have a history of stroke. -Have low blood pressure or uncontrolled high blood pressure. -Have current or past stomach ulcers. -Have liver problems. -Have kidney problems or are having kidney dialysis. -Have any other medical conditions. |
| Indications | 5 Star is indicated for the treatment of erectile dysfunction. Administration and Dosage: For most patients, the recommended dose is 50 mg taken as needed, approximately 1 hour before sexual activity. However, 5 Star may be taken anywhere from 30 minutes to 4 hours prior to sexual activity. The maximum recommended dosing frequency is once per day.Based on effectiveness and tolerance, the dose may be increased to a maximum of 100 mg or decreased to 25 mg. Note: For 5 Star Chewable Tablets, the tablet should be chewed before swallowing. |
| Contraindications | Sildenafil is contraindicated in patients with known hypersensitivity to sildenafil or any component of the tablet. |
| Warnings and Precautions | Cardiovascular: Sildenafil should be used with caution in patients with cardiovascular disease, as sexual activity may increase cardiac risk. Its vasodilatory effects can cause significant blood pressure drops in sensitive individuals. It is not recommended for patients with unstable cardiac conditions where sexual activity is inadvisable. Extra caution is needed in those with left ventricular outflow obstruction, blood pressure regulation issues, or a recent (within 6 months) history of heart attack, stroke, serious arrhythmias, severe hypotension, uncontrolled hypertension, unstable angina, or advanced heart failure. Prolonged Erection and Priapism: Prolonged erections lasting more than 4 hours, as well as priapism (painful erections lasting more than 6 hours), require immediate medical attention to prevent the risk of penile tissue damage and permanent loss of erectile function. Anti-hypertensives: Sildenafil has systemic vasodilatory properties and may further lower blood pressure in patients taking antihypertensive medications including alpha-blockers. Caution is advised when co-administering sildenafil with these agents due to the potential for additive hypotensive effects. Combination With Other PDE5 Inhibitors or Other Erectile Dysfunction Therapies: The safety and efficacy of combinations of sildenafil with other PDE5 Inhibitors, or other pulmonary arterial hypertension (PAH) treatments containing sildenafil, or other treatments for erectile dysfunction have not been studied. |
| Use in Special Populations | Patients with renal impairment: No dose adjustment is necessary for mild and moderate renal impairment. A starting dose of 25 mg should be considered for patients with severe renal impairment. Patients with hepatic impairment: Since sildenafil clearance is reduced in patients with hepatic impairment (Child-Pugh Class C), a 25 mg dose should be considered. Based on efficacy and tolerability, the dose may be gradually increased to 50 mg, up to 100 mg, as needed. Pregnancy and Lactation: Sildenafil is not intended for use in women. There are no adequate and well-controlled studies in pregnant or breast-feeding women. Pediatric Use: Sildenafil is not indicated for use in pediatric patients. Safety and effectiveness have not been established in pediatric patients. Side Effects/ Adverse Reactions: Common side effects of sildenafil include headache, dyspepsia (indigestion), flushing, and myalgia (muscle pain). Other reported side effects include epistaxis, insomnia, erythema, dyspnea, rhinitis, diarrhea, pyrexia, gastritis, and sinusitis. If any of these effects persist or worsen, it is important to seek medical advice. |
| Drug Interactions | Nitrates: Sildenafil must not be used with nitrates (such as nitroglycerin) in any form, due to the risk of a serious drop in blood pressure. Alpha-blockers: Use caution when co-administering alpha-blockers with sildenafil because of potential additive blood pressure lowering effects. Ritonavir and other CYP3A4 enzyme inhibitors (erythromycin, ketoconazole, or itraconazole): Co-administration of ritonavir, a strong CYP3A4 enzyme inhibitor, greatly increased the systemic exposure of sildenafil. |
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