Product Overview
[Drug name]
Generic name: Sildenafil citrate tablets
Trade name: LangMei Sildenafil citrate tablets 50mg*2 tablets
Pinyin full code: LangMei GouYuanSuanXiDiNaFeiPian 5Omg*2Pian
[Main ingredients]
The main ingredient of this product is sildenafil citrate. Chemical name: 1-{4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1hydro-pyrazolo[4,3d]pyrimidin-5-yl)benzenesulfonyl}-4-methylpiperazine
Citrate. Molecular formula: C22H30N6O4SxC6H8O7Molecular weight: 666.70
[Properties]
This product is a white or off-white 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*7 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 0.54 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 (AUO): 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 P4503A4 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 2smg of the drug within 48 hours. Sildenafil can enhance the antihypertensive effect of nitrates, so patients taking any dosage form of nitric oxide donors and nitrates are prohibited from taking sildenafil. When sildenafil needs to be used in combination with α-receptor blockers, the patient has been treated with α-receptor blockers to achieve a stable state before sildenafil treatment, and sildenafil should be taken from 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 the pharmacokinetic data of healthy volunteers, a single oral dose of 100 mg resulted 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, liver damage (such as cirrhosis), severe renal damage (creatinine clearance less than 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 far lower than the peak concentration, it is not known whether nitrates can be safely taken at this time. Patients who are known to be allergic 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 the treatment of erectile dysfunction, including sildenafil. Since sildenafil dilates systemic vasodilation, whether this vasodilation effect of the supine blood pressure of healthy volunteers will have adverse consequences for patients with cardiovascular disease, especially during sexual activity.
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[Precautions]
General matters When diagnosing erectile dysfunction, the underlying cause should be identified, and appropriate treatment should be determined after a comprehensive medical examination. Before using sildenafil on patients, the following important issues should be noted: Hypotension when used in combination with alpha-blockers or antihypertensive drugs Alpha-blockers: PDE5 (phosphodiesterase type 5) inhibitors should be used with caution when used in combination with alpha-blockers. PDE5 inhibitors (including this product) and alpha-blockers are both vasodilators and have the effect of lowering blood pressure. When vasodilators are used in combination, it can be expected that the effects on blood pressure may be additive. In some patients, the combination of these two types of drugs can significantly lower blood pressure and cause symptoms of hypotension (such as dizziness, lightheadedness, and syncope) (see [Drug Interactions]). The following situations should also be noted: Before a patient receives sildenafil treatment, he should have reached a stable state of alpha-blocker treatment. Patients who take alpha-blockers alone to treat hemodynamic instability are at increased risk of hypotension symptoms after taking PDE5 inhibitors in combination.- For patients who have reached a stable state on alpha-blocker therapy, PDE5 inhibitors should be started at the lowest dose. - For patients who are already taking the ideal dose of PDE5 inhibitors, alpha-blocker therapy should be started at the lowest dose. The simultaneous use of PDE5 inhibitors may further reduce blood pressure as the dose of alpha-blockers is gradually increased. - The safety of combined use of PDE5 inhibitors and alpha-blockers may be affected by other factors, including insufficient intravascular volume and other antihypertensive drugs. Antihypertensive drugs: Sildenafil dilates systemic blood vessels and may enhance the antihypertensive effect of other antihypertensive drugs. Major clinical trials included patients who were taking multiple antihypertensive drugs at the same time. Another independent drug interaction study showed that when hypertensive patients taking 5mg or 10mg of amlodipine were given 100mg of sildenafil citrate tablets, systolic and diastolic blood pressures were further reduced by an average of 8mmHg and 7mmHg respectively (see [Drug Interactions]).In three drug interaction studies, patients with benign prostatic hyperplasia (BPH) who were receiving doxazosin therapy to a stable state were concurrently treated with the alpha-blocker doxazosin (4 mg and 8 mg) and sildenafil (25 mg, 50 mg, or 100 mg). In these study populations, a further average decrease in supine blood pressure of 7/7 mmHg, 9/5 mmHg, and 8/4 mmHg, respectively, and a further average decrease in standing blood pressure of 6/6 mmHg, 11/4 mmHg, and 4/5 mmHg, respectively, was observed. If a higher dose of sildenafil and doxazosin (4 mg) were taken simultaneously, individual patients reported symptoms of postural hypotension within 1 to 4 hours after taking the drug, including dizziness, lightheadedness, and lightheadedness, but not syncope. Patients taking alpha-blockers concurrently with sildenafil may cause symptoms of hypotension in some patients. Therefore, sildenafil doses exceeding 25 mg should not be taken within 4 hours of taking alpha-blockers. Safety database analysis showed that there was no difference in side effects among patients taking sildenafil with or without antihypertensive drugs.In post-marketing experience, there have been reports of prolonged erections and priapism associated with sildenafil. 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. Concomitant use with other PDE5 inhibitors or other erectile dysfunction treatments: The safety and efficacy of other PDE5 inhibitors, or other pulmonary arterial hypertension (PAH) treatments containing sildenafil (Revatio), or other erectile dysfunction treatments combined with this product have not been studied. Such combined use may further lower blood pressure. Therefore, combined use is not recommended. Effect on bleeding: Post-marketing bleeding events have been reported in patients who have taken sildenafil citrate tablets. A causal relationship between this product and these events has not been established. Sildenafil citrate tablets have no effect on human bleeding time, whether used alone or in combination with aspirin. However, sildenafil citrate tablets enhanced the antiaggregative effect of sodium nitroprusside (a nitric oxide donor) on human platelets in vitro.In addition, in rabbits under anesthesia, the combination of heparin and sildenafil has an additive effect on the prolongation of bleeding time, but similar human studies have not been conducted. The safety of sildenafil citrate tablets in patients with bleeding disorders and active peptic ulcers is currently unknown. Patient Information Physicians should explain to patients that sildenafil is prohibited from being taken simultaneously with nitrates (regardless of whether the latter are taken regularly or intermittently). Physicians should inform patients that sildenafil has the potential to enhance the antihypertensive effect of alpha-blockers and other antihypertensive drugs. Taking sildenafil and alpha-blockers simultaneously may cause hypotension symptoms in some patients. When sildenafil and alpha-blockers need to be used together, patients should have reached a stable state of alpha-blocker treatment before sildenafil treatment, and sildenafil should be started at the lowest dose. Physicians should explain to patients that sexual activity has potential risks to the heart when cardiovascular risk factors are present. If symptoms such as angina, dizziness, and nausea occur at the beginning of sexual activity, sexual activity should be stopped and these situations should be discussed with the doctor.Effects on the eyes: Physicians should inform patients that if they experience sudden vision loss in one or both eyes, they should immediately stop taking all phosphodiesterase type 5 (PDE5) inhibitors, including sildenafil citrate tablets, and consult a physician. This condition may be a manifestation of non-arteritic anterior ischemic optic neuropathy (NAION), a disease that can cause vision loss, including permanent loss. Rare reports of NAION related to the duration of medication have been reported in all post-marketing applications of PDE5 inhibitors. An observational case-crossover study evaluated the risk of NAION when using PDE5 inhibitors just before the onset of NAION (within 5 half-lives) compared with the use of PDE5 inhibitors over a period of time. The results showed that the risk of NAION increased by approximately 2 times, with a risk estimate of 2.15 (95% CI 1.06, 4.34). A similar study reported consistent results, with a risk estimate of 2.27 (95% CI 0.99, 5.20). Other risk factors for NAION (such as optic disc "crowding") may be involved in the NAION that occurred in these studies.Rare post-marketing reports and observational studies of the association between PDE5 inhibitor use and NAION have not confirmed a causal relationship between PDE5 inhibitor use and NAION (see [Adverse Reactions]/Post-Marketing Experience). Published literature shows that in the general population, the annual incidence of NAION is 2.5 to 11.8 cases per 100,000 men (≥50 years old). If sudden vision loss occurs, patients should be advised to stop taking sildenafil and consult a physician immediately. For patients with potential NAION risk factors, doctors should consider whether they will be adversely affected by the use of PDE5 inhibitors. Individuals who have already experienced NAION have an increased risk of NAION recurrence. Doctors should inform patients who have experienced unilateral NAION that their risk of NAION recurrence will increase regardless of whether vasodilators such as PDE5 inhibitors will have adverse effects on them. In these patients, PDE5 inhibitors (including sildenafil) should be used with caution only when the expected benefits outweigh the risks. Patients with "crowded" optic discs are also thought to be at higher risk for NAION than the general population; however, evidence is insufficient to support screening potential users of PDE5 inhibitors, including this product, for this uncommon condition.There are no controlled clinical data on the safety or efficacy of this product for patients with retinitis pigmentosa (a small number of whom have inherited retinal phosphodiesterase disorders). It is not certain that these events are directly related to the use of PDE5 inhibitors or are related to other factors. Physicians should inform patients who have experienced unilateral NAION that they are at increased risk of another NAION regardless of whether vasodilator drugs such as PDE5 inhibitors have adverse effects on them (see "[Adverse Reactions]/Post-Marketing Experience/Special Sensations" section). Hearing loss: Physicians should inform patients that if hearing loss or loss occurs suddenly, they should stop taking PDE5 inhibitors (including this product) and seek medical attention as soon as possible. Such events may be accompanied by tinnitus and dizziness, which have been reported to be temporally related to the use of PDE5 inhibitors (including sildenafil citrate tablets). However, it is not certain whether such events are directly related to the use of PDE5 inhibitors or other factors (see [Adverse Reactions]/Pre-Marketing Experience and Post-Marketing Experience). Doctors should warn patients: After sildenafil citrate tablets were approved for marketing abroad, there were a small number of cases of prolonged erections (more than 4 hours) and abnormal erections (painful erections as part of pre-marketing experience and post-marketing experience).Doctors should warn patients: After the approval of sildenafil citrate tablets for marketing abroad, there have been a small number of reports of prolonged erections (more than 4 hours) and abnormal erections (painful erections for more than 6 hours). If the erection lasts for more than 4 hours, the patient should seek medical attention immediately. If abnormal erections are not treated immediately, penile tissue may be damaged and may lead to permanent loss of erectile function. Doctors should inform patients that this product should not be used in combination with other PDE5 inhibitors. The safety and effectiveness of this product in combination with other PDE5 inhibitors have not been studied. Patient counseling advice on sexually transmitted diseases: Sildenafil has no protective effect against sexually transmitted diseases. Patients should be informed of measures to prevent sexually transmitted diseases (including human immunodeficiency virus, HIV) as appropriate. Effects on the ability to drive and use machines Because dizziness and visual changes have been reported in clinical studies of sildenafil, patients should understand their possible reactions to sildenafil before driving and operating machines. The effects of sildenafil on the ability to drive and use machines have not been studied.
