Udenafil is a medication used in the treatment of erectile dysfunction (ED) in men. It belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors. Marketed under the trade name Zydena, udenafil was developed by Dong-A Pharmaceutical Co., Ltd., a South Korean company, and has been available in various markets since its initial approval in 2005.
How Udenafil Works
Udenafil works by influencing the body’s natural response to sexual stimulation, affecting blood flow to the penis. When a man is sexually aroused, nitric oxide (NO) is released in the corpus cavernosum, the spongy tissue in the penis. Nitric oxide then activates an enzyme called guanylate cyclase, which increases levels of cyclic guanosine monophosphate (cGMP).
cGMP is a molecule that relaxes the smooth muscle cells in the penile arteries, allowing more blood to flow into the penis, which results in an erection. An enzyme called phosphodiesterase type 5 (PDE5) breaks down cGMP, controlling its levels and ending muscle relaxation. Udenafil acts as a selective inhibitor of this PDE5 enzyme.
By inhibiting PDE5, udenafil prevents the premature breakdown of cGMP, leading to its prolonged presence. This maintains the relaxation of smooth muscle cells in the penile arteries, thereby facilitating increased blood flow and a more robust erection. Udenafil does not cause an erection directly; sexual stimulation remains necessary for nitric oxide release and subsequent cGMP production.
Medical Uses and Administration
Udenafil is primarily prescribed for erectile dysfunction, defined as the inability to achieve or maintain an erection sufficient for satisfactory sexual intercourse. It improves blood flow to the penis, enabling satisfactory sexual performance with sexual stimulation.
This medication is administered orally in tablet form. A common starting dose is 100 mg, taken 30 minutes to an hour before anticipated sexual activity. The effects of udenafil can be observed within 30 to 40 minutes after oral administration, though this can vary among individuals.
The duration of udenafil’s effects can last up to 24 hours, providing a broad window for sexual activity. It can be taken with or without food, but consuming a high-fat meal might delay its onset of action. Patients are advised not to take more than one dose per day.
In some cases, a 200 mg dose may be prescribed, and udenafil’s pharmacokinetic properties also allow for once-daily dosing in addition to on-demand use. Consult a healthcare provider for personalized advice on dosage and administration to ensure optimal results and minimize adverse effects.
Potential Side Effects and Precautions
Like all medications, udenafil can cause side effects, though they are mild to moderate in severity. Common side effects reported in clinical trials include facial flushing and headache. Other potential side effects may include dizziness, nasal congestion, and dyspepsia.
Serious side effects, while less common, require immediate medical attention. These can include a sudden decrease or loss of vision or hearing, or an erection lasting longer than four hours (priapism). Priapism can cause permanent damage to the penis if not treated promptly.
Udenafil is contraindicated in patients who are taking organic nitrates or nitric oxide donors. This is because PDE5 inhibitors, including udenafil, can significantly enhance the hypotensive effects of nitrates, leading to a dangerous drop in blood pressure, syncope, or even myocardial ischemia. This interaction can be life-threatening.
Patients with severe cardiovascular disorders, such as heart failure or unstable angina, should not use udenafil. Caution is also advised when udenafil is used with alpha-blockers, often prescribed for hypertension or benign prostatic hyperplasia, as this combination can lead to orthostatic hypotension. Medical supervision is recommended, even if the interaction is less clinically relevant in patients on long-term alpha-blocker therapy.
Udenafil Compared to Other Treatments
Udenafil belongs to the same class of drugs as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra). Each of these PDE5 inhibitors has distinct pharmacokinetic profiles, influencing their onset and duration of action.
Udenafil has a rapid onset of action, with peak plasma concentrations reached within 1 to 1.5 hours. This is comparable to sildenafil and vardenafil, which also have quick onsets. However, udenafil’s duration of action is longer, with a plasma half-life ranging from 11 to 13 hours.
This longer half-life differentiates udenafil from sildenafil and vardenafil, which have half-lives of 3 to 5 hours. While tadalafil has an even longer half-life of 17.5 hours, allowing for a duration of effect up to 36 hours, udenafil’s extended duration offers a wider window for spontaneity.