Zidena, 100 mg 4 pcs

Pharmacodynamics

Udenafil is a selective reversible inhibitor of cyclic guanosine monophosphate (cGMP) – specific phosphodiesterase type 5 (PDE-5).

Udenafil has no direct relaxant effect on the isolated cavernous body, but with sexual stimulation it increases the relaxant effect of nitric oxide by inhibiting FDE-5, which is responsible for the breakdown of cGMF in the cavernous body.

The consequence of this is relaxation of arterial smooth muscles and blood flow to the tissues of the penis, which causes an erection. The drug has no effect in the absence of sexual stimulation.

In vitro studies have shown that udenafil is a selective inhibitor of the enzyme FDE-5. FDE-5 is present in the smooth muscles of the corpora cavernosa, in smooth muscles of vessels of internal organs, in skeletal muscles, platelets, kidneys, lungs and cerebellum.

Udenafil is 10,000 times more potent as an inhibitor against FDE-5 than against FDE-1, FDE-2, FDE-3 and FDE-4, which are localized in the heart, brain, blood vessels, liver and other organs.

In addition, udenafil is 700 times more active against FDE-5 than against FDE-6, found in the retina and responsible for color vision. Udenafil does not inhibit FDE-11, which explains the absence of myalgia, lower back pain and testicular toxicity.

Udenafil improves erection and the possibility of successful intercourse. The action of the drug has an optimal duration of up to 24 hours. The effect appears as early as 30 minutes after taking the drug in the presence of sexual arousal.

Udenafil does not significantly change systolic and diastolic blood pressure in healthy subjects compared to placebo when lying and standing (mean maximum decrease is 1.6/0.8 mm Hg and 0.2/4.6 mm Hg, respectively).

Udenafil does not cause changes in color recognition (blue/green) due to its low affinity for FDE-6. Udenafil does not affect visual acuity, electroretinogram, intraocular pressure and pupil size.
The study of udenafil in men showed no clinically significant effect of the drug on the number and concentration of sperm, motility and morphology of sperm.

Pharmacokinetics

Intake

Uddenafil is rapidly absorbed after oral administration. The time to reach maximum plasma concentration (tmax) is 30-90 minutes (on average, 60 minutes). The half-life (t ½) is 12 hours, high plasma protein binding of udenafil (93.9%) extends its effectiveness up to 24 hours after taking just one dose.

Eating a high-calorie meal has no effect on the absorption of udenafil.

Alcohol intake of 112 mL of alcohol (in terms of 40% ethyl alcohol) in combination with oral udenafil at a dose of 200 mg has no effect on the pharmacokinetic profile of udenafil.

Metabolism

Udenafil is primarily metabolized with participation of the cytochrome isoenzyme (CYP)3A4.
In healthy humans, the total clearance of udenafil is 755 ml/min. After oral administration udenafil is excreted as metabolites in the feces.

Udenafil does not accumulate in the body. No significant changes in its pharmacokinetics were detected when administered daily in healthy volunteers in doses of 100 and 200 mg per day for 10 days.

Indications

The treatment of erectile dysfunction characterized by the inability to achieve or maintain an erection of the penis sufficient for satisfactory intercourse.

Active ingredient

Composition

How to take, the dosage

The drug is taken orally, regardless of meals. The recommended dose of the drug is 100 mg, taken 30 minutes before the intended sexual activity.

The dose can be increased up to 200 mg, taking into account individual effectiveness and tolerability of the drug.

The maximum recommended frequency of use is once daily.

Interaction

Cytochrome P450 CYP3A4 isoenzyme inhibitors (ketoconazole, itraconazole, ritonavir, indinavir, cimetidine, erythromycin, grapefruit juice) may increase the effect of udenafil.

Ketoconazole (400 mg dose) increases the bioavailability and Cmax of udenafil (100 mg dose) by almost two times (212%) and 0.8 times (85%), respectively.

Ritonavir and indinavir significantly enhance the effects of udenafil. Dexamethasone, rifampin and anticonvulsants (carbamazepine, phenytoin and phenobarbital) may accelerate the metabolism of udenafil, so co-administration with the above drugs weakens the effect of udenafil.

The co-administration of udenafil (30 mg/kg, orally) and nitroglycerin (2.5 mg/kg once intravenously) showed no effect on the pharmacokinetics of udenafil in experimental studies, but the simultaneous use of nitroglycerin and udenafil is not recommended because of the possible decrease in blood pressure.

Udenafil and drugs from the group of alpha-blockers are vasodilators, so when taken together they should be prescribed in minimal doses.

Special Instructions

Sexual activity has potential risks for patients with cardiovascular disease, so erectile dysfunction treatment, including the use of udenafil, should not be performed in men with heart disease in which sexual activity is not recommended.

Patients with left ventricular outflow tract obstruction (aortic stenosis) may be more sensitive to the action of vasodilators, including FDE inhibitors. Despite the absence of cases of prolonged erection (more than 4 hours) and priapism (painful erection lasting more than 6 hours) in clinical studies, these phenomena are characteristic of this class of drugs.

If an erection lasts more than 4 hours (regardless of pain), patients should seek medical attention immediately. If not treated promptly, priapism can lead to permanent damage to erectile tissue and erectile function.

In the absence of clinical data on the use of udenafil in patients over 71 years of age, this category of patients is not recommended for this drug. It is not recommended to use udenafil in combination with other treatments of erectile dysfunction.

Contraindications

The potential risk of complications during sexual activity in patients with cardiovascular disease such as unstable angina or angina pectoris occurring during sexual intercourse; chronic heart failure (NYHA functional class II-IV) developed within the past 6 months; uncontrolled heart rhythm disorders should be considered.

With caution, use udenafil in patients with a predisposition to priapism, as well as in patients with anatomical deformity of the penis, in the presence of a penile implant.

Side effects

Side effects observed during clinical trials of udenafil, depending on their frequency of occurrence: very often – ≥10% of cases; often – 1-10%; sometimes – 0.1-1%.

Cardiovascular system: very often – flushes to the face.

CNS disorders: sometimes – dizziness, neck muscle stiffness, paresthesia.

Visual organs: often – red eyes; sometimes – blurred vision, pain in the eyes, increased lacrimation.

Skin disorders: sometimes – eyelid swelling, facial edema, urticaria.

The digestive system: often – dyspepsia, abdominal discomfort; sometimes – nausea, toothache, constipation, gastritis.

Respiratory system: often – nasal congestion; sometimes – shortness of breath, dry nose.

Motor system disorders: sometimes – periarthritis.

The body in general: often – headache, discomfort in the chest, a feeling of fever; sometimes – chest pain, abdominal pain, fatigue, thirst.

Other adverse events have also been described during postmarketing observations with udenafil use: palpitations, nosebleeds, tinnitus, diarrhea, allergic reactions (skin rash, erythema), prolonged erections, feeling of general discomfort, feeling of cold or heat, postural dizziness, cough.

Overdose

On a single dose of 400 mg, adverse events were comparable to those observed with udenafil at lower doses, but were more frequent.

Treatment: symptomatic. Dialysis does not accelerate excretion of udenafil.

Pregnancy use

Zidena is not intended for use in women according to its registered indication.