Sildenafil is a vasoactive agent used to treat erectile dysfunction and reduce symptoms in patients with pulmonary arterial hypertension (PAH). Sildenafil elevates levels of the second messenger, cGMP, by inhibiting its breakdown via phosphodiesterase type 5 (PDE5). PDE5 is found in particularly high concentrations in the corpus cavernosum, erectile tissue of the penis. It is also found in the retina and vascular endothelium.
Vardenafil is an oral therapy for the treatment of erectile dysfunction. It is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Penile erection is a hemodynamic process initiated by the relaxation of smooth muscle in the corpus cavernosum and its associated arterioles. During sexual stimulation, nitric oxide is released from nerve endings and endothelial cells in the corpus cavernosum.
Silvitra composition: Sildenafil Citrate 100mg and Vardenafil 20mg. It is advisable to divide the tablets into 2 or 4 parts, which was also stipulated by the manufacturer – there are convenient divisions on the tablets.
Take the pill followed 30-40 minutes before sexual intercourse, and the effect lasts about 8-10 hours. It is worth remembering that alcohol and fatty foods reduce the effectiveness of the effect several times, as a result of which the time to erection increases. It should also be taken into account the fact that this medication contains the maximum recommended daily dose of sildenafil and vardenafil.
Erections are controlled by the parasympathetic nervous system. Upon sexual stimulation, a decrease in vascular resistance is mediated by acetylcholine and nitric oxide resulting in vasodilation. The hemodynamic mechanism of an erection is comprised of five stages. During the latent stage, arterial and carvernous smooth muscle relaxation occurs.
Vasodilation results in high levels of blood flow causing the penis to grow to its full size. This stage is called tumescence. During the full-erection stage, blood flow fills penis sinusoids and outflow is restricted. This is followed by the rigid-erection phase during which the cavernous muscles contract causing the penis to become rigid. Little blood flow occurs during this stage. During the final stage, detumescence, the cavernous muscles relax and blood flows out of the penis.
Vardenafil is used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Part of the physiological process of erection involves the release of nitric oxide (NO) in the corpus cavernosum. This then activates the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation in the corpus cavernosum, resulting in increased inflow of blood and an erection. Vardenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum. This means that, with vardenafil on board, normal sexual stimulation leads to increased levels of cGMP in the corpus cavernosum which leads to better erections. Without sexual stimulation and no activation of the NO/cGMP system, vardenafil should not cause an erection.
Sildenafil inhibits the cGMP-specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum located around the penis. Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) by sildenafil enhances erectile function by increasing the amount of cGMP.
Vardenafil inhibits the cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum located around the penis. Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) by vardenafil enhances erectile function by increasing the amount of cGMP.
Metabolism: Sildenafil appears to be completely metabolized in the liver to 16 metabolites. Its metabolism is mediated mainly by cytochrome P450 microsomal isozymes 3A4 (major route) and 2C9 (minor route). The major circulating metabolite, N-demethylated metabolite, has PDE selectivity similar to the parent drug and ~50% of its in vitro potency. The N-demethylated metabolite is further metabolized to an N-dealkylated N,N-de-ethylated metabolite. Sildenafil also undergoes N-dealkylation followed by N-demethylation of the piperazine ring. / Vardenafil - is metabolized predominantly by the hepatic enzyme CYP3A4, with contribution from the CYP3A5 and CYP2C isoforms.
Absorption: Sildenafil - >90% absorbed with ~40% reaching systemic circulation unchanged following first-pass metabolism. / Vardenafil - is rapidly absorbed with absolute bioavailability of approximately 15%.
Route of elimination: Sildenafil: After either oral or intravenous administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of the administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose). / Vardenafil: After oral administration, is excreted as metabolites predominantly in the feces (approximately 91-95% of administered oral dose) and to a lesser extent in the urine (approximately 2-6% of administered oral dose).
Half life: Sildenafil - 4 hours / Vardenafil - 4-5 hours
All medicines may cause side effects, but many people have no, or minor, side effects.Some medical conditions may interact with Sildenafil & Vardenafil.
Tell your doctor or pharmacist if you have any medical conditions.
Common Sildenafil side effects may include: flushing (warmth, redness, or tingly feeling), headache, dizziness, heartburn, nausea, or upset stomach, abnormal vision (blurred vision, changes in color vision), runny or stuffy nose, nosebleeds, sleep problems (insomnia) or muscle pain, back pain.
Common Vardenafil side effects may include: flushing (warmth, redness, or tingly feeling), stuffy nose, sinus pain, headache, dizziness, upset stomach or back pain.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider.
