Mechanism of Action
An erection of the penis during sexual stimulation is caused by increased penile blood flow produced by the relaxation of penile arteries and cavernous muscle. This relaxation is mediated by nitric oxide release in the nerve endings and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Nitric oxide activates guanylate cyclase, which results in increased levels of cGMP producing smooth muscle relaxation in the corpus cavernosum. Tadalafil is a potent and selective inhibitor of phosphodiesterase 5 (PDE5), an enzyme of the cavernous bodies responsible for degradation of cGMP. CGMC accumulation allows maintenance of erectile function.
Because sexual stimulation is required to initiate the local release of NO, the inhibitory effect of tadalafil on PDE5 does not appear without it. PDE5 is found in smooth muscle of the corpora cavernosa, vascular and visceral smooth muscle, skeletal muscle, platelets, kidneys, lungs, pancreas and cerebellum. Tadalafil is 10,000 times more potent on PDE5 than other phosphodiesterases like PDE3 found mostly in the heart and blood vessels or PDE7 found in the retina.
Following this selective inhibition, tadalafil is capable of maintaining erectile function without significant side effects due to inhibition of other phosphodiesterases.
After administration of a single dose of tadalafil, peak plasma concentrations occur between 30 min and 6 hours (average of 2 hours). The absolute bioavailability after oral doses has not been determined. The rate and extent of absorption of tadalafil are not affected by concomitant food intake.
After an oral dose, the mean apparent volume of distribution is about 63 L indicating a broad distribution. When administered in therapeutic doses, 94% of the drug binds 94% to plasma proteins. Less than 0.0005% of the administered dose recovered in the semen of healthy volunteers.
Tadalafil is principally metabolised by the cytochrome P450 CYP3A4, causing an inactive metabolite to be methylated and then eliminated as glucuronide. Most of the dose is excreted in the feces (61%) and urine (36%). The average clearance of tadalafil is 2.5 l / h and the mean half-life is 17.5 hours in healthy subjects.
Indications and dosing
Treatment of erectile dysfunction:
Adults: recommended dosage 10 mg taken prior to sexual activity regardless to meals. If the 10 mg dose does not produce the proper effect, it may be increaced to 20 mg. It can be administered from 30 minutes to 12 hours before sexual activity. The efficacy of tadalafil may last up to 36 hours after administration. Daily use of medication during long period is not recommended as it has not been established long-term safety after prolonged daily dosing
Elderly: No dose adjustment is required in the elderly patients.
Children and adolescents: Tadalafil is not indicated for individuals below 18 years of age. The efficacy and safety of tadalafil in people under 18 years have not been established
Treatment of benign prostatic hyperplasia (BPH)
Adults: The recommended dose is 5 mg once daily, administered at the same time. When co-administered with finasteride, the recommended dose remains 5 mg once a day.
Combined treatment of erectile dysfunction and benign prostatic hyperplasia
Adults: The recommended dose is 5 mg once daily, administered at the same time regardless of sexuall activity.
Patients with renal impairment and hepatic impairment: 10 mg prior to anticipated sexual activity regardless to meals. There are no sufissient data available on administration of doses more than 10 mg.
Diabetic patients: No dose adjustment is required in diabetic patients.
Tadalafil is a noble medicine, but like any medicine, it must be prescribed by a doctor. In some conditions it requires closer medical supervision:
- Drug allergies
- Abnormalities of the penis such as fibrosis, scarring or curvatures
- Sickle cell anemia
- leukemia, lymphomas and other tumors
- severe gastric ulcer or gastritis
- Kidney or liver problems
- abnormal bleeding
- Heart problems
- High pressure
- Vision problems or problems in the retina
Like all medicines, CIALIS can cause side effects, although not everybody gets them. These effects are usually mild to moderate intensity.
The side effects reported very commonly in patients taking tadalafil were headaches.
Among the side effects reported frequently in patients taking tadalafil were backaches, muscle aches, facial flushing, nasal congestion, dizziness and indigestion.
The side effects reported uncommonly are allergic reactions including rashes, abdominal pain, heartburn, blurred vision, eye pain, increased sweating, palpitations, fast heartbeat, high blood pressure, low blood pressure and chest pain.
Rare side effects reported in patients taking tadalafil include fainting, seizures, passing memory loss, swelling of the eyelids, red eyes, sudden decrease or loss of hearing, hives and nose bleeds.
- Ensures you can enjoy a normal sex life. In contrast to other drugs that have an effect of 17-36 hours
- It is available by prescription in multiple doses, allowing you to test multiple variations and see what dose suits you. Always consult your doctor if you want to try another dose
- It is a quick and prolonged effect. The active ingredient, tadalafil ensures that the operation is faster than other variants such as Viagra. Tadalafil works after 15 minutes