Alprostadil (Erectile dysfunction)

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Alprostadil is similar to the natural substance in the body called prostaglandin E1. It widens blood vessels so that blood can flow into the penis more easily. This makes it easier for a man to have an erection.

Alprostadil is used for “erectile dysfunction” including weak erections or impotence.

Contents

[edit] BRAND NAMES

[edit] STRUCTURE

Alprostadil.jpg

[edit] MECHANISM OF ACTION

Alprostadil is a synthetic stable form of prostaglandin E1 with various pharmacological actions that include vasodilation, inhibition of platelet aggregation, inhibition of gastric secretion, stimulation of intestinal smooth muscle and stimulation of uterine smooth muscle.

Alprostadil induces erection by relaxation of trabecular smooth muscle and by dilation of cavernosal arteries. Alprostadil for injection works fast and can give an erection in just 5 to 20 minutes

[edit] INDICATIONS

  • Treatment of erectile dysfunction
  • Adjunct to other diagnostic tests in the diagnosis of erectile dysfunction.

[edit] DOSAGE

Alprostadil for injection is administered by direct intracavernosal injection. A 1/2-inch, 27- to 30-gauge needle is recommended. The dose of Alprostadil should be individualized by careful titration under a physician’s supervision. The first injections of Alprostadil must be done at the physician's office by medically trained personnel. Self-injection therapy by the patient can be started only after the patient is properly instructed and well trained in the self-injection technique.

Erectile Dysfunction of Vasculogenic, Psychogenic, or Mixed Etiology. Dosage titration should be initiated at 2.5 micrograms of alprostadil. If there is a partial response, the dose may be increased by 2.5 micrograms to a dose of 5 micrograms and then in increments of 5 to 10 micrograms, depending upon erectile response, until the dose that produces an erection suitable for intercourse and not exceeding a duration of one hour is reached. If there is no response to the initial 2.5 microgram dose, the second dose may be increased to 7.5 micrograms, followed by increments of 5 to 10 micrograms.

Erectile Dysfunction of Pure Neurogenic Etiology (Spinal Cord Injury). Dosage titration should be initiated at 1.25 micrograms of alprostadil. The dose may be increased by 1.25 micrograms to a dose of 2.5 micrograms, followed by an increment of 2.5 micrograms to a dose of 5 micrograms, and then in 5 microgram increments until the dose that produces an erection suitable for intercourse and not exceeding a duration of one hour is reached.

Maintenance Therapy: Self-Injection: The dose of Alprostadil that is selected for selfinjection treatment should provide the patient with an erection that is satisfactory for sexual intercourse and that is maintained for no longer than one hour. If the duration of erection is longer than one hour, the dose of Alprostadil should be reduced. Self-injection therapy for use at home should be initiated at the dose that was determined in the physician's office; however, if dose adjustment is required, it should be done only after consultation with the physician. The dose should be adjusted in accordance with the titration guidelines described above. The lowest effective dose should be employed. The recommended frequency of injection is no more than three times weekly with at least 24 hours between each dose. The patient may expect an erection to develop within 5 to 20 minutes.

The effectiveness of Alprostadil for long-term use of up to six months has been documented in an uncontrolled, self-injection study. The mean dose of alprostadil at the end of six months was 20.7 micrograms. In the majority of patients, the maintenance dose is between 5 micrograms and 20 micrograms. Maintenance doses of greater than 60 micrograms are not recommended.

Alprostadil as an Adjunct to the Diagnosis of Erectile Dysfunction: In the simplest diagnostic test for erectile dysfunction (pharmacologic testing), patients are monitored for the occurrence of an erection after an intracavernosal injection of Alprostadil. Extensions of this testing include the use of Alprostadil as an adjunct to laboratory investigations, such as duplex or Doppler imaging, 133Xenon washout tests, radioisotope penogram, and penile arteriography, to allow visualization and assessment of penile vasculature. For any of these tests, a single dose of Alprostadil that induces an erection with firm rigidity should be used.

[edit] CONTRAINDICATIONS

  • Known hypersensitivity to alprostadil.
  • Abnormal penile anatomy such as angulation, cavernosal fibrosis, or Peyronie’s disease
  • Conditions that might result in long-lasting erections (Priapism), such as sickle cell anemia or trait, leukemia, or tumor of the bone marrow (multiple myeloma)
  • Men with penile implants
  • Alprostadil should not be used in men for whom sexual activity is inadvisable (e.g. severe heart disease).
  • The transurethral delivery system of Alprostadil should not be used for sexual intercourse with a pregnant woman unless the couple uses a condom barrier.

[edit] WARNINGS AND PRECAUTIONS

  • Prolonged Erection/Priapism: Prolonged erection (erection lasting 4 to 6 hours) and priapism (erection lasting over 6 hours) are known to occur following intracavernosal administration of vasoactive substances. If priapism is not treated immediately, penile tissue damage and permanent loss of potency may result. The patient should be instructed to immediately report to his physician or, if unavailable, to seek immediate medical assistance for any erection that persists for longer than 4 hours. Treatment of priapism should be according to established medical practice.
  • Alprostadil for injection can cause penile fibrosis or Peyronie’s disease.
  • Do not use alprostadil for injection more than 3 times a week
  • Wait at least 24 hours between doses
  • Do not change the dose without talking to your healthcare provider
  • Do not reuse the syringe or needle

[edit] INTERACTIONS

Use of alprostadil for injection in patients who take anticoagulants, such as warfarin or heparin, should be with precaution as they may have increased tendency for bleeding after alprostadil injections

[edit] PREGNANCY AND LACTATION

  • Alprostadil is not indicated for use in newborns, children, or women.

[edit] SIDE EFFECTS

The most common side effect of alprostadil for injection was penile pain, reported by 37% of patients in clinical studies. Other side effects were prolonged erection, penile fibrosis and injection site hematoma. To lower the risk of prolonged erections or priapism, alprostadil for injection should be titrated slowly to the lowest effective dose.

[edit] RELATED LINKS

[edit] BIBLIOGRAPHY

[edit] REFERENCES

Sexual dysfunction pharmacotherapies
PDE5 inhibitors Avanafil   Sildenafil   Tadalafil   Vardenafil
Prostaglandins (Erectile dysfunction) Alprostadil
Premature ejaculation Dapoxetine