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Active ingredient: Alprostadil - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Fibrinolytic Agents
  • Platelet Aggregation Inhibitors
  • Vasodilator Agents

Dosage Forms

  • Liquid
  • Powder for solution
  • Solution
  • Suppository

Brands / Synonyms

Alprostadil Prostoglandin E1; Befar; Caverject; Caverject Impulse; Edex; l-Prostaglandin E1 ; Muse; PGE1; Prink; Prostaglandin E1; Prostin VR; Prostin VR Pediatric

Indications

For palliative, not definitive, therapy to temporarily maintain the patency of the ductus arteriosus until corrective or palliative surgery can be performed in neonates who have congenital heart defects and who depend upon the patent ductus for survival. Also for the treatment of erectile dysfunction due to neurogenic, vasculogenic, psychogenic, or mixed etiology.

Pharmacology

Alprostadil (prostaglandin E1) is produced endogenously to relax vascular smooth muscle and cause vasodilation. In adult males, the vasodilatory effects of alprostadil on the cavernosal arteries and the trabecular smooth muscle of the corpora cavernosa result in rapid arteriolar inflow and expansion of the lacunar spaces within the corpora. As the expanded corporal sinusoids are compressed against the tunica albuginea, venous outflow through the subtunical vessels is impeded and penile rigidity develops. This is referred to as the corporal veno-occlusive mechanism. In infants, the vasodilatory effects of alprostadil increase pulmonary or systemic blood flow.

Mechanism of Action

Alprostadil causes vasodilation by means of a direct effect on vascular and ductus arteriosus (DA) smooth muscle, preventing or reversing the functional closure of the DA that occurs shortly after birth. This results in increased pulmonary or systemic blood flow in infants. In cyanotic congenital heart disease, alprostadil's actions result in an increased oxygen supply to the tissues. In infants with interrupted aortic arch or very severe aortic coarctation, alprostadil maintains distal aortic perfusion by permitting blood flow through the DA from the pulmonary artery to the aorta. In infants with aortic coarctation, alprostadil reduces aortic obstruction either by relaxing ductus tissue in the aortic wall or by increasing effective aortic diameter by dilating the DA. In infants with these aortic arch anomalies, systemic blood flow to the lower body is increased, improving tissue oxygen supply and renal perfusion. When administered by intracavernosal injection or as an intraurethral suppository, alprostadil acts locally to relax the trabecular smooth muscle of the corpora cavernosa and the cavernosal arteries. Swelling, elongation, and rigidity of the penis result when arterial blood rapidly flows into the corpus cavernosum to expand the lacunar spaces. The entrapped blood reduces the venous blood outflow as sinusoids compress against the tunica albuginea.

Absorption

The absolute bioavailability of alprostadil has not been determined.

Toxicity

Oral, mouse: LD50 = 186 mg/kg; Oral, rat: LD50 = 228 mg/kg. Apnea, bradycardia, pyrexia, hypotension, and flushing may be signs of drug overdosage.

Biotrnasformation / Drug Metabolism

Alprostadil must be infused continuously because it is very rapidly metabolized. As much as 80% of the circulating alprostadil may be metabolized in one pass through the lungs, primarily by beta- and omega-oxidation.

Contraindications

Caverject

Alprostadil should not be used in patients who have a known hypersensitivity to the drug, in patients who have conditions that might predispose them to priapism, such as sickle cell anemia or trait, multiple myeloma, or leukemia, or in patients with anatomical deformation of the penis, such as angulation, cavernosal fibrosis, or Peyronie's disease. Patients with penile implants should not be treated with Alprostadil.

Alprostadil should not be used in women or children and is not for use in newborns.

Alprostadil should not be used in men for whom sexual activity is inadvisable or contraindicated.

Drug Interactions

Prostin VR Pediatric Sterile Solution

No drug interactions have been reported between Prostin VR Pediatric and the therapy standard in neonates with restricted pulmonary or systemic blood flow. Standard therapy includes antibiotics, such as penicillin and gentamicin; vasopressors, such as dopamine and isoproterenol; cardiac glycosides; and diuretics, such as furosemide.

Caverject

The potential for pharmacokinetic drug-drug interactions between alprostadil and other agents has not been formally studied.

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