Each tablet of Sildera 50 mg (Tablets) contains Sildenafil Citrate equivalent to Sildenafil 50 mg.
Each tablet of Sildera 100 mg (Tablets) contains Sildenafil Citrate equivalent to Sildenafil 100 mg.
Pharmacology: Pharmacodyanmics: Erectile dysfunction: Does not directly cause penile erections, but affects the response to sexual stimulation. The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which result in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation and inflow of blood to the corpus cavernosum. Sildenafil enhances the effect of NO by inhibiting phosphodiesterase type 5 (PDE-5), which is responsible for degradation of cGMP in the corpus cavernosum; when sexual stimulation causes local release of NO, inhibition of PDE-5 by sildenafil causes increased levels of cGMP in the corpus cavernosum, resulting in smooth muscle relaxation and inflow of blood to the corpus cavernosum; at recommended doses, it has no effect in the absence of sexual stimulation.
Pharmacokinetics: Sildenafil is rapidly absorbed after an oral dose, with a bioavailability of about 40% (25% to 63%). Onset of action is about 60 minutes and duration of action is about 2-4 hours. Peak plasma concentrations are attained within 30 to 120 minutes but delayed by 60 minutes with a high fat meal; the rate of absorption is reduced when sildenafil is given with food and slower with a high fat meal. Sildenafil is widely distributed into tissues and is about 96% bound to plasma proteins. It is metabolised in the liver mainly by cytochrome P450 isoenzymes CYP3A4 (the major route) and CYP2C9 (minor route). The major metabolite, N-desmethylsildenafil (UK-103320) also has some activity. Volume of distribution at steady state (Vdss) is 105 litres. The terminal half-life of sildenafil and the N-desmethyl metabolite are about 4 hours. Sildenafil is excreted as metabolites, mainly in the faeces (80%), and to a lesser extent the urine (13%). Clearance may be reduced in the elderly and in patients with hepatic or severe renal impairment.
Treatment of erectile dysfunction which is the inability to achieve or maintain a penile erection sufficient for satisfactory sexual performance.
Adults: The usual dose is sildelnafil 50 mg about one hour before sexual intercourse. The dose may be increased or decreased depending on response. The maximum recommended dose is 100 mg, and sildenafil should not be taken more than once in 24 hours.
Elderly > 65 years: Use with caution: Starting dose of 25 mg should be considered.
Dosage considerations for patients stable on alpha-blockers: Initial 25 mg.
Dosage adjustment for concomitant use of potent CYP3A4 inhibitors: Erythromycin, itraconazole, ketoconazole: Starting dose of 25 mg should be considered.
Protease inhibitors: Maximum sildenafil dose: 25 mg every 48 hours.
Dosage adjustment in renal impairment: Clcr < 30 mL/minute: Starting dose of 25 mg should be considered.
Dosage adjustment in hepatic impairment: Child-Pugh class A and B: Starting dose of 25 mg should be considered; not studied in severe impairment (Child-Pugh class C).
Mode of Administration: Orally.
In studies of healthy volunteers with single dose up to 800 mg, adverse events were similar to those seen at lower doses, but incidence rates were increased.
Management of sildenafil overdose includes standard supportive and therapies as required.
For severe hypotensive episodes, consideration can be given to placing the patient in the Trendelenburg position, initiating fluid resuscitation, providing judicious use of an IV α-adrenergicagonist (e.g., phenylephrine), providing a combined α- and β-adrenergicagonist (norepinephrine) for blood pressure support (although exacerbation or development of an acute ischemic syndrome could occur), and/or providing intra-aortic balloon counterpulsation as indicated. Hypotensive episodes resulting from inadvertent use of sildenafil and a nitrate/nitrite should be managed in similar fashion.
Renal dialysis is not expected to enhance clearance of drug, since sildenafil and its active metabolite are highly bound to plasma proteins, and renal clearance does not constitute a major elimination pathway.
Patients who are hypersensitive to sildenafil or any component of the formulation; concurrent use (regularly/intermittently) of organic nitrates in any form (eg, nitroglycerin, isosorbide dinitrate).
Decreases in blood pressure may occur due to vasodilator effects; use with caution in patients with left ventricular outflow obstruction (aortic stenosis or hypertrophic obstructive cardiomyopathy); may be more sensitive to hypotensive actions. Concurrent use with alpha-adrenergic antagonist therapy or substantial ethanol consumption may cause symptomatic hypotension; patients should be hemodynamically stable prior to initiating therapy at the lowest possible dose. Use with caution in patients with hypotension (<90/50 mmHg); uncontrolled hypertension (>170/110 mmHg); life-threatening arrhythmias, stroke or MI within the last 6 months; cardiac failure or coronary artery disease causing unstable angina; safety and efficacy have not been studied in these patients. There is a degree of cardiac risk associated with sexual activity; therefore, physicians should consider the cardiovascular status of their patients prior to initiating any treatment for erectile dysfunction.
Sildenafil should be used with caution in patients with anatomical deformation of the penis (angulation, cavernosal fibrosis, or Peyronie's disease) and in patients who have conditions which may predispose them to priapism (sickle cell anemia, multiple myeloma, leukemia). All patients should be instructed to seek medical attention if erection persists >4 hours.
Vision loss may occur rarely and be a sign of nonarteritic anterior ischemic optic neuropathy (NAION) . Risk may be increased with history of vision loss. Other risk factors for NAION include low cup-to-disc ratio ("crowded disc"), coronary artery disease, diabetes, hypertension, hyperlipidemia, smoking, and age >50 years. May cause dose related impairment of color discrimination. Use caution in patients with retinitis pigmentosa; a minority have genetic disorders of retinal phosphodiesterases (no safety information available). Sudden decrease or loss of hearing has been reported rarely; hearing changes may be accompanied by tinnitus and dizziness. A direct relationship between therapy and vision or hearing loss has not been determined.
The potential underlying causes of erectile dysfunction should be evaluated prior to treatment. The safety and efficacy of sildenafil with other treatments for erectile dysfunction have not been established; use is not recommended. Use with caution in patients taking strong CYP3A4 inhibitors or alpha-blockers. Concomitant use with all forms of nitrates is contraindicated. If nitrate administration is medically necessary, it is not known when nitrates can be safety administered following the use of sildenafil (per manufacturer) the ACC/AHA 2007 guidelines supports administration of nitrates only if 24 hours have elapsed.
Use caution in patients with bleeding disorders or with active peptic ulcer disease; safety and efficacy have not been established. Use with caution in the elderly, or patients with renal or hepatic dysfunction; dose adjustment may be needed.
Use in Pregnancy: Category B, Teratogenic effects were not observed in animal studies. There are no adequate and well controlled studies in pregnant women. Less than 0.001% appears in semen.
Use in Lactation: Excretion in breast milk is unknown. However, sildenafil should be used with caution.
Adverse effects most commonly reported with sildenafil are headache, flushing, and dyspepsia. Also common are visual disturbances such as blurred vision, photophobia, chromatopsia, cyanopsia, eye irritation, pain and redness of the eyes. Retinal haemorrhage has occurred, and non-arteritic anterior ischaemic optic neuropathy (NAION) causing permanent loss of vision has been reported rarely. Other common adverse effects include dizziness, insomnia, anxiety, vertigo, epistaxis, nasal congestion, pyrexia, and gastrointestinal disturbances such as diarrhoea and vomiting. Priapism can occur.pther adverse effects include skin rashes, erythema, alopecia, limb and/or back pain, myalgia, facial oedema, fluid retention, paraesthesia, and urinary tract infection. Dyspnoea, cough, rhinitis, sinusitis, bronchitis, and cellulitis can occur. Sudden decrease or loss of hearing has been reported. Other reported effects include anaemia, leucopenia, gynaecomastia, urinary frequency or incontinence, haematuria, and seizures. Cerebrovascular haemorrhage and transient ischaemic attacks have occurred. There have also been reports of palpitations, syncope, hypertension, hypotension,and serious cardiovascular events including myocardial infarction, arrhythmias, tachycardia, unstable angina, and sudden cardiac death.
Metabolism/Transport Effects of Substrate: Sildenafil is a substrate of CYP2C9 (minor), 3A4 (major); inhibits CYP1A2 (weak), 2C9 (weak), 2C19 (weak), 2D6 (weak), 2E1 (weak), 3A4 (weak).
Avoid Concomitant Use: Avoid concomitant use of sildenafil with amyl nitrate, phosphodiesterase 5 inhibitors, vasodilators (organic nitrates).
Increased Effect/Toxicity: Sildenafil may increase the levels/effects of alpha 1-blockers, amyl nitrate, antihypertensive, bosentan, HMG-CoA reductase inhibitors, phosphodiesterase 5 inhibitors, vasodilators (organic nitrates).
The levels/effects of sildenafil may be increased by antifungal agents (azole derivatives, systemic), conivaptan, CYP3A4 inhibitors (moderate), CYP3A4 inhibitors (strong), dasatinib, macrolide antibiotic, protease inhibitors, sapropterin.
Decreased Effect: The levels/effects of sildenafil may be decreased by bosentan, CYP3A4 inducers (strong), deferasirox, etravirine, herbs (CYP3A4 inducers), peginterferon alfa-2b.
Food: Amount and rate of absorption of sildenafil is reduced when taken with a high-fat meal. Serum concentrations/toxicity may be increased with grapefruit juice; avoid concurrent use.
Herb/Nutraceutical: St. John's wort may decrease sildenafil levels.
G04BE03 - sildenafil ; Belongs to the class of drugs used in erectile dysfunction.
Tab 50 mg (diamond shape, blue and convex film-coated tablet imprinted with logo ATC in triangle on one side and 50 on the side) x 1 x 4's. 100 mg (diamond shape, blue and convex film-coated tablet imprinted with logo ATC in triangle on one side and 100 on the other side) x 1 x 4's.