Product Overview
[Drug name]
Generic name: Sildenafil citrate tablets
Trade name: LangMei Sildenafil citrate tablets 50mg*10 tablets
Pinyin full code: LangMei ZuoZuoSuanXiDiNaFeiPian 50mg*10Pian
[Main ingredients]
The main ingredients of this product are: Sildenafil citrate, its chemical name is: 1-{4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonyl}-4-methylpiperazine citrate. Molecular formula: C22H30N6O4S·C6H8O7 Molecular weight: 666.70
[Properties]
This product is a film-coated tablet, which is white or off-white after removing the coating.
[Indications/Main Functions]
Sildenafil is suitable for the treatment of erectile dysfunction.
[Specifications]
50mg*10 tablets
[Dosage and Administration]
For most patients, the recommended dose is 50 mg, taken as needed approximately 1 hour before sexual activity; however, it can be taken at any time within 0.5 to 4 hours before sexual activity. Based on efficacy and tolerability, the dose can be increased to 100 mg (maximum recommended dose) or reduced to 25 mg. Take up to once a day. In the absence of sexual stimulation, the recommended dose of sildenafil is ineffective. The following factors are associated with increased plasma sildenafil levels (AUC): age over 65 years (increase of 40%), liver damage (such as cirrhosis, increase of 80%), severe renal impairment (creatinine clearance <30 ml/min, increase of 100%), and concurrent use of potent cytochrome P450 3A4 inhibitors [ketoconazole, itraconazole (increase of 200%), erythromycin (increase of 182%), saquinavir (increase of 210%)]. Since higher plasma levels may increase both efficacy and the incidence of adverse events, the starting dose for these patients is 25 mg. A study conducted in healthy subjects without HIV infection showed that ritonavir can significantly increase the blood level of sildenafil (AUC increased by 11 times, see [Drug Interactions]). In view of this, it is recommended that patients taking ritonavir at the same time should not take more than 25 mg per 48 hours. Sildenafil can enhance the antihypertensive effect of nitrates, so patients taking any dosage form of nitric oxide donors and nitrates should not take sildenafil. When sildenafil needs to be used in combination with α-blockers, the patient should have achieved a stable state with α-blocker treatment before sildenafil treatment, and sildenafil should be started at the lowest dose (see [Drug Interactions]).
[Adverse Reactions]
See instructions for details.
[Contraindications]
Nitrates: Due to the known effects of sildenafil citrate tablets on the nitric oxide/cGMP pathway (see [Pharmacology and Toxicology]), sildenafil can enhance the hypotensive effect of nitrates. Therefore, patients taking nitric oxide donors (such as any form of organic nitrates or organic nitrites), whether taking them regularly or intermittently, are contraindicated. PDE5 inhibitors (including sildenafil) are prohibited from being used in combination with guanylate cyclase agonists (such as riociguat) because this may cause symptomatic hypotension. It is not clear when patients can safely take nitrates (if necessary) after taking sildenafil. Based on pharmacokinetic data from healthy volunteers, a single oral dose of 100 mg results in a plasma sildenafil concentration of approximately 2 ng/ml (peak plasma concentration of approximately 440 ng/ml) 24 hours later (see [Pharmacokinetics]). The following patients had plasma sildenafil concentrations 3 to 8 times higher than healthy volunteers 24 hours after taking the drug: patients over 65 years old, with liver damage (such as cirrhosis), severe renal damage (creatinine clearance below 30ml/min), and those taking strong inhibitors of cytochrome P4503A4 such as erythromycin. Although the blood concentration of sildenafil 24 hours after taking the drug is much lower than the peak concentration, it is not known whether nitrates can be safely taken at this time. Patients with known allergies to any of the ingredients in this product are contraindicated. Warning Cardiovascular: Sexual activity is potentially dangerous to the heart in patients with existing cardiovascular disease.Therefore, patients whose cardiovascular status is not suitable for sexual activity should generally not use drugs for erectile dysfunction, including sildenafil. Sildenafil causes systemic vasodilation, resulting in a transient decrease in blood pressure in the supine position in healthy volunteers (mean maximum decrease of 8.4/5.5 mmHg) (see [Pharmacology and Toxicology]). In most patients, this effect is usually negligible, but physicians should carefully consider whether this vasodilation will cause adverse consequences in patients with cardiovascular disease before prescribing, especially during sexual activity. Patients with the following underlying diseases may be particularly sensitive to the effects of vasodilators, including sildenafil - including left ventricular outflow tract obstruction (such as aortic stenosis, idiopathic hypertrophic subaortic stenosis) and diseases with severe impairment of autonomic blood pressure control. Such patients should use the drug with caution. At present, there are no controlled clinical trial data on the safety and efficacy of sildenafil in the following populations. Prescriptions should be made with caution for these patients: patients who have had myocardial infarction, shock, or life-threatening arrhythmias within the last 6 months; patients with resting hypotension (blood pressure below 90/50 mmHg) or hypertension (blood pressure above 170/110 mmHg); patients with heart failure or unstable angina due to coronary heart disease; patients with pigmentary retinitis (a few patients with this disease have hereditary abnormalities of retinal phosphodiesterase). Patients with sickle cell anemia or related anemia. Prolonged erection and priapism: Foreign approval After the launch of sildenafil citrate tablets, there have been a few reports of prolonged erection (more than 4 hours) and priapism (painful erection for more than 6 hours).If an erection persists for more than 4 hours, the patient should seek medical attention immediately. If priapism is not treated immediately, penile tissue may be damaged and permanent erectile dysfunction may occur. Sildenafil should be used with caution in patients with the following diseases: penile anatomical malformations (such as penile deviation, cavernous fibrosis, Peyronie's disease), diseases that predispose to priapism (such as sickle cell anemia, multiple myeloma, leukemia). However, there are no controlled clinical data on the safety or efficacy of this product in patients with sickle cell anemia or related anemias. Adverse reactions caused by co-administration with ritonavir: Concomitant administration of the protease inhibitor ritonavir significantly increases the blood concentration of sildenafil (AUC increases 11 times). Sildenafil should be used with caution in patients taking ritonavir. There is limited information on the effects of high blood concentrations of sildenafil on subjects, except that visual abnormalities are more common at high doses. Some healthy subjects taking high doses of sildenafil (200-800 mg) reported decreased blood pressure, syncope, and prolonged erection. To reduce the possibility of adverse events in patients taking ritonavir, it is recommended to reduce their sildenafil dosage.
