Basic Information
Drug name: Viagra
Alias: Sildenafil Citrate Tablets, Sildenafil
Foreign name: SILDENAFIL CITRATE TABLETS VIAGRA
Dosage form: white crystalline powder
1. Pharmaceutical ingredients
The main components of the product and its chemical name are: 1-[4-ethoxy-3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1 hydrogen-pyrazolo[ 4,3d]pyrimidin-5-yl)benzenesulfonyl]-4-methylpiperazine citrate
Chemical Structure:
Molecular formula: C22H30N6O4S·C6H8O7
Molecular weight: 666.70
2. Appearance
This product is a blue film-coated tablet, which appears white after removing the coating.
3. Adapt to symptoms
Sildenafil is indicated for the treatment of erectile dysfunction.
4. Product Specifications
Tablets, (1) 25mg, (2) 50mg, (3) 100mg, aluminum-plastic packaging
5. Usage and dosage
It needs to be used under the diagnosis and prescription of the doctor, and take it exactly according to the dosage that the doctor tells you. Your healthcare provider will tell you how much and when to take it. A healthcare provider may adjust the dose if necessary. for reference only
Take about 1 hour before sexual activity. If needed, it can also be taken 30 minutes to 4 hours before sexual activity. Viagra can be taken before or after meals. If you take it after a high-fat meal (such as a burger or fries), it may take a little longer for the drug to work. Do not take Viagra more than 1 time a day. If you accidentally overdose on Viagra, contact your doctor immediately or go to the nearest hospital emergency room.
For most patients, the recommended dose is 50 mg, taken as needed about 1 hour before sexual activity; however, it can be taken anytime within 0.5-4 hours before sexual activity. based on efficacy and tolerability, the dose may be increased to 100 mg (maximum recommended dose) or decreased to 25 mg. Take up to 1 time per day. The recommended dose of sildenafil does not work in the absence of sexual stimulation.
The following factors are associated with increased plasma sildenafil levels (AUC): age over 65 years (40% increase), hepatic impairment (eg, cirrhosis, 80% increase), severe renal impairment (creatinine clearance [30 mL/min] , increased 100%), concurrently taking potent cytochrome P4503A4 inhibitors [ketoconazole, itraconazole (200% increase), erythromycin (182% increase), saquinavir (210% increase)]. Because higher plasma levels may increase both efficacy and adverse event rates, a starting dose of 25 mg is appropriate for these patients.
A study in healthy subjects without HIV infection showed that Ritonavir significantly increased sildenafil plasma levels (11-fold increase in AUC, see "Drug Interactions"). In view of this, it is recommended that patients taking ritonavir do not exceed a maximum dose of 25 mg every 48 hours.
Sildenafil can enhance the antihypertensive effect of nitrates, so patients taking nitric oxide donors and nitrates in any dosage form should not take sildenafil.
When concomitant use of sildenafil and alpha-blockers is required, the patient has been stabilized on alpha-blocker therapy prior to sildenafil treatment, and sildenafil should be started at the lowest dose.
6. Adverse reactions
Viagra® can cause serious side effects. Rarely reported side effects include: persistent erection (priapism). Get medical help right away if you have an erection that persists for more than 4 hours. Priapism can cause permanent damage to your penis if not treated right away. Sudden loss of vision in one or both eyes. Sudden loss of vision in one or both eyes is a sign of a serious eye disease called nonarterial anterior ischemic optic neuropathy (NAION). Stop taking Viagra and notify your healthcare provider right away if you experience sudden loss of vision in one or both eyes. Sudden hearing loss or hearing loss. Some people may experience ringing in their ears (tinnitus) or dizziness. If you experience these symptoms, stop taking Viagra® and contact your doctor immediately.
The most common side effects of Viagra are: headache, flushing, upset stomach, abnormal vision such as changes in visual color (such as a blue halo) and blurred vision, stuffy or runny nose, back pain, muscle pain, nausea, dizziness, rash .
Additionally, heart attack, stroke, irregular heartbeat, and death rarely occurred in men taking Viagra®. The vast majority, though not all, of these people had pre-existing heart problems before taking Viagra®. It is not known whether Viagra® is causing these problems.
Tell your healthcare provider if any side effects bother you or if side effects persist.
These are not all possible side effects of Viagra®. For more information, talk to your healthcare provider for medical advice about side effects.
Pre-market experience:
In clinical trials worldwide, more than 3,700 patients (aged 19-87 years) took sildenafil. Among them, more than 550 patients have been treated for more than one year.
In placebo-controlled clinical trials, the discontinuation rate due to adverse events in the experimental group (2.5%) was not significantly different from the placebo group (2.3%). Adverse events were generally transient and mild to moderate in nature.
In various forms of clinical trials, adverse events reported by patients in the experimental groups were generally similar. In fixed-dose trials, the incidence of certain adverse events increased with increasing dose. In general, flexible-dose trials are more reflective of the recommended dosing of the drug, and the nature of adverse events seen in trials is similar to that in fixed-dose trials.
In flexible-dose, placebo-controlled clinical trials taking sildenafil as recommended (as needed), patients reported the following adverse events:
Although the following adverse events occurred in 2%, the incidence in the experimental group was the same as that in the placebo group. They are: respiratory infections, back pain, flu symptoms and joint pain.
In the fixed-dose trial, dyspepsia (17%) and visual abnormalities (11%) were more common in the 100-mg dose group than in the low-dose group. Above the recommended dose range, adverse events manifested similarly but were reported more frequently.
The following are adverse events with an incidence of [2%] in controlled clinical trials. It is uncertain whether its occurrence is due to sildenafil. Events that may be drug-related are included here, but minor events and inaccurate reporting are omitted.
Systemic reactions: facial edema, photosensitivity, shock, fatigue, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury.
Cardiovascular System: Angina pectoris, atrioventricular block, migraine, syncope, tachycardia, palpitations, hypotension, orthostatic hypotension, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, abnormal electrocardiogram, myocardium sick.
Digestive system: Vomiting, glossitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, dry mouth, abnormal liver function, rectal bleeding, gingivitis.
Blood and Lymphatic System: Anemia and Leukopenia.
metabolism and nutrition: thirst, edema, gout, unstable diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemia, hypernatremia.
Musculoskeletal System: Arthritis, arthropathy, muscle pain, tendon rupture, tenosynovitis, bone pain, muscle weakness, synovitis.
Nervous System: Ataxia, hypertonia, neuralgia, neuropathy, paresthesia, tremor, vertigo, depression, insomnia, somnolence, dreaminess, slowed reflexes, dysesthesia.
Respiratory System: Asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, phlegm, cough.
Skin and its appendages: urticaria, herpes simplex, itching, sweating, skin ulcers, contact dermatitis, exfoliative dermatitis.
Special Senses: Mydriasis, conjunctivitis, photophobia, tinnitus, eye pain, deafness, ear pain, eye hemorrhage, cataract, dry eye.
Genitourinary system: cystitis, nocturia, urinary frequency, breast enlargement, urinary incontinence, abnormal ejaculation, genital edema, and lack of orgasm.
Post-market experience:
Cardiovascular System
The following serious cardiovascular adverse events with time-linked use of sildenafil have been reported post-marketing: myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebral hemorrhage, transient cerebral ischemia, and hypertension. The vast majority (though not all) of these patients had pre-existing cardiovascular risk factors. many of the reported events occurred during or immediately after sexual activity; a few occurred shortly after taking sildenafil before sexual activity. There are also some reported incidents hours or even days after taking medication or sexual activity. For these events, it is uncertain whether they are directly related to sildenafil, sexual activity, pre-existing cardiovascular disease, a combination of these, or other factors (see Warnings for important cardiovascular information). ).
special feeling:
There have been individual case reports of sudden post-marketing hearing loss or loss, time-correlated with the use of PDE5 inhibitors, including this product. Some of these patients may have underlying diseases or other factors that may have contributed to otologic-related adverse events. There is limited follow-up information for many cases. It cannot be determined whether sudden hearing loss or loss is directly related to the use of this product, whether it is related to the patient's existing risk factors for hearing loss, and whether it is a combination of the above two factors or whether there are other reasons (see "[Notes] Matters]/Information to Patients" section).
other events
Other adverse events reported post-marketing that were time-linked to sildenafil use but did not occur in premarketing studies were:
Nervous System: Seizures and Anxiety.
Genitourinary: prolonged erection, priapism (see Warnings), and hematuria.
Special Senses: Double vision, transient vision loss or decreased vision, red eye or eye congestion, eye burning sensation, eye swelling and pressure, increased intraocular pressure, retinal vascular disease or hemorrhage, vitreous detachment, permacular edema, nasal Nv and so on.
There have been rare reports of time-related non-arterial anterior ischemic optic neuropathy (NAION) in the postmarketing use of PDE5 inhibitors, including Viagra. NAION is a disease that can cause vision loss, including permanent loss, and in most, but not all cases, these patients have underlying anatomical or vascular underlying or risk factors for NAION, including but not limited to: low cup Disc ratio, age over 50 years, diabetes, hypertension, coronary artery disease, hyperlipidemia and smoking.
It cannot be determined that these events are directly related to the use of PDE5 inhibitors; or related to the patient's underlying vascular risk factors or anatomical defects; or a combination of the two; or other factors.
Hemolymphatic system: The clinical relevance of vaso-occlusive crisis and Viagra-treated men with ED is unclear. [1]
7. Contraindications
Sildenafil enhances the antihypertensive effect of nitrates due to the known effects of this product on the nitric oxide/cGMP pathway (see "Pharmacology and Toxicology"). Therefore, patients taking nitrates in any dosage form, whether regularly or intermittently, are contraindicated.
It is not known when patients can safely take nitrates (if needed) after taking sildenafil. based on pharmacokinetic data in 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) after 24 hours (see "Pharmacokinetics"). ). Plasma sildenafil concentrations are 3-8 times higher than healthy volunteers 24 hours after taking the drug in the following patients: age 65 years or older, liver damage (such as cirrhosis), severe renal damage (creatinine clearance below 30 ml/min), concurrent Take strong inhibitors of cytochrome P4503A4 such as erythromycin. Although sildenafil plasma levels 24 hours after dosing are well below peak levels, it is not known whether nitrates can be safely administered at this time.
Patients with known hypersensitivity to any of the ingredients in this product are contraindicated.
8. Precautions
General
Erectile dysfunction should be diagnosed at the same time as the underlying cause, followed by a thorough medical examination to determine the appropriate treatment plan.
Before administering sildenafil to a patient, there are some important issues to be aware of:
Caution should be exercised when PDE5 (phosphodiesterase type 5) inhibitors are co-administered with alpha-blockers. PDE5 inhibitors (including this product) and alpha-blockers are both vasodilators and have the effect of lowering blood pressure. Potentially additive effects on blood pressure can be expected when vasodilators are used concomitantly. In some patients, the combination of these two drugs can significantly lower blood pressure, resulting in symptoms of hypotension (eg, dizziness, lightheadedness, fainting) (see DRUG INTERACTIONS).
The following should also be noted:
– Patients should have reached a steady state on alpha-blocker therapy before receiving sildenafil. Hemodynamically unstable patients treated with alpha-blockers alone are at increased risk of developing hypotensive symptoms with concomitant PDE5 inhibitors.
– In patients who have stabilized on alpha-blocker therapy, PDE5 inhibitors should be started at the lowest dose.
– For patients already taking an ideal dose of a PDE5 inhibitor, alpha-blocker therapy should be started at the lowest dose. Concomitant administration of PDE5 inhibitors may further reduce blood pressure with a stepwise increase in the dose of alpha-blockers.
– The safety of combining PDE5 inhibitors with alpha-blockers may be influenced by other factors, including insufficient intravascular volume and other antihypertensive drugs.
Sildenafil dilates systemic blood vessels and may enhance the antihypertensive effect of other antihypertensive drugs.
Patients taking multiple antihypertensive drugs were included in the main clinical trial. Another independent drug interaction study showed that the addition of 100 mg of this product in hypertensive patients taking 5 mg or 10 mg of amlodipine resulted in a further reduction of systolic and diastolic blood pressure by an average of 8 mmHg and 7 mmHg.
Patients with benign prostatic hyperplasia (BPH) taking the alpha-blockers doxazosin (4 mg) and sildenafil (25 mg) concomitantly reduced supine systolic and diastolic blood pressure by an average of 7 mmHg each. If higher doses of sildenafil and doxazosin (4 mg) are taken at the same time, individual patients have reported symptoms of orthostatic hypotension within 1 to 4 hours after taking the drug. Concomitant use of sildenafil in patients on alpha-blocker therapy may cause symptoms of hypotension in some patients. Therefore, sildenafil doses exceeding 25 mg should not be taken within 4 hours of taking an alpha-blocker.
The safety of sildenafil in patients with bleeding disorders and active peptic ulcer is unknown.
Sildenafil should be used with caution in patients with the following diseases: anatomical deformities of the penis (eg, deviated penis, cavernous fibrosis, Peyronie's disease), diseases that predispose to priapism (eg, sickle cell anemia, multiple myeloma, leukemia) ).
The safety and efficacy of other treatments for erectile dysfunction in combination with this product have not been studied. Therefore, combined use is not recommended.
This product had no effect on bleeding time in humans, either alone or in combination with aspirin. In vitro, this product enhances the anti-aggregation effect of sodium nitroprusside, a nitric oxide donor, on human platelets. In rabbits under anesthesia, the combination of heparin and sildenafil has an additive effect on prolongation of bleeding time, but similar human studies have not been conducted.
Patient Information
Physicians should explain to patients that sildenafil should not be taken concurrently with nitrates (regardless of whether the latter is administered regularly or intermittently).
Physicians should inform patients that sildenafil has the potential to enhance the antihypertensive effect of alpha-blockers and other antihypertensive drugs. Concomitant use of sildenafil and an alpha-blocker may cause symptoms of hypotension in some patients. When concomitant use of sildenafil and alpha-blockers is required, patients should have reached a steady state on alpha-blocker therapy before sildenafil treatment, and sildenafil should be started at the lowest dose.
Physicians should educate patients about the potential cardiac risk of sexual activity in the presence of pre-existing cardiovascular risk factors. If symptoms such as angina, dizziness, and nausea occur at the beginning of sexual activity, stop sexual activity and discuss these conditions with your doctor.
Physicians should inform patients that they should immediately stop taking all phosphodiesterase type 5 (PDE5) inhibitors, including Viagra, and consult their doctor if they experience sudden loss of vision in one or both eyes. This condition may be a manifestation of non-arterial anterior ischemic optic neuropathy (NAION), a condition that can cause vision loss, including permanent loss, that has been associated with time in all postmarketing applications of PDE5 inhibitors Rare report of NAION. It cannot be determined that these events are directly related to the use of PDE5 inhibitors or to other factors.
Physicians should inform patients who have had a unilateral NAION that they are at increased risk for a second NAION regardless of whether vasodilator drugs such as PDE5 inhibitors will adversely affect them.
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 can be accompanied by tinnitus and dizziness, and have been reported to be time-correlated with administration of PDE5 inhibitors, including this product. However, it is uncertain whether such events are directly related to the use of PDE5 inhibitors or other factors.
Physicians should warn patients that there have been a small number of reports of prolonged erection (more than 4 hours) and priapism (painful erection more than 6 hours) after foreign approval of this product. If an erection persists for more than 4 hours, the patient should seek immediate medical attention. If priapism is not treated immediately, penile tissue may be damaged and permanent erectile dysfunction may result.
Physicians should inform patients that this product should not be co-administered with other PDE5 inhibitors. The safety and efficacy of this product in combination with other PDE5 inhibitors have not been studied.
Sildenafil is not protective against sexually transmitted diseases. Patients should be informed of measures to prevent sexually transmitted diseases (including human immunodeficiency virus, HIV), as appropriate.
