Простаглиин E1

Описание

Prostaglandin E1 is an endogenous prostaglandin with vasodilatory, anti-platelet, and anti-hypertensive activities. It is in clinical use for the treatment of erectile dysfunction and the emergency management of infants with patent ductus arteriosus. It has also been used in the treatment of peripheral arterial occlusive disease (PAD).

Химические свойства

Crystalline Solid

Использование

A primary Prostaglandin; easily crystallized from purified biological extracts. Vasodilator (peripheral)

Показания

Alprostadil (prostaglandin E₁ [PGE₁]; Edex, Topiglan) exerts a number of effects, including systemic vasodilation, inhibition of platelet aggregation, and stimulation of intestinal motility. PGE₁ relaxes isolated smooth muscle cells contracted by norepinephrine. It has become widely used in the treatment of ED. Alprostadil binds with PGE receptors and results in a cyclic adenosine monophosphate (cAMP) mediated smooth muscle relaxation. Little is known about the pharmacokinetics of PGE₁, but it is believed that as much as 80% is metabolized in one pass through the lungs. Such rapid degradation probably accounts for its lack of significant cardiovascular side effects when administered intracavernosally. PGE₁ can also be metabolized in the penis.

Всемирная организация здравоохранения(ВОЗ)

Alprostadil, a prostaglandin with vasodilating and platelet antiaggregatory activity, was introduced in 1984 for the treatment of chronic arterial obstruction. Intravenous administration of the drug has been associated with adverse effects that have sometimes been severe. These include allergic reactions, pulmonary oedema and cardiac insufficiency. Interactions with antihypertensive agents, vasodilators, anticoagulants and inhibitors of platelet aggregation have also occurred. This has led the German agency to modify the approved product information of alprostadil preparations to warn against these adverse effects.

Биологические функции

Prostaglandin E1 is produced endogenously to relax vascular smooth muscle and cause vasodilation by activating the adenylate cyclase/cAMP pathway. Recent studies show that the cAMP is important in the PGE1 relaxation of penile erectile tissue and vasodilation of penile resistance arteries. Moreover, agents that stimulate the release of cAMP also crossactivate the NO/cGMP cascade.

Общее описание

PGE1, Alprostadil (Prostin VR Pediatric), is a naturally occurring prostaglandin that has found particular use in maintaining a patent (opened) ductus arteriosus in infants with congenital defects that restrict pulmonary or systemic blood flow.
Alprostadil must be administered intravenously continually at a rate of approximately 0.1 μg/kg/min to maintain the patency of the ductus arteriosus until corrective surgery can be performed. Up to 80% of circulating alprostadil may be metabolized in a single pass through the lungs. Because apnea has been observed in 10% to 12% of neonates with congenital heart defects, this product should be administered only when ventilatory assistance is immediately available. Other commonly observed side effects include decreased arterial blood pressure, which should be monitored during infusion; inhibited platelet aggregation, which might aggravate bleeding tendencies; and diarrhea.

Биологическая активность

Prostaglandin with some selectivity for EP 3 and EP 4 receptors (K i values are 1.1, 2.1, 36, 10? and 33 nM for mouse EP 3 , EP 4 , EP 1 , EP 2 and IP receptors respectively). Inhibits platelet aggregation and is a vasodilator in vivo .

Механизм действия

PGE₁ is not orally effective. Its therapeutic success depends on its being injected intracavernosally or administered transurethrally or intraurethrally. PGE₁ has also been used in combination with other agents, such as papaverine. The injection does not appear to produce any long-term side effects on penile smooth muscle. Transurethral therapy with alprostadil, such as MUSE (alprostadil urethral suppository or medicated urethral system for erection) is also an effective therapeutic technique, and there may be a role for this form of administration in selected patients with ED.The intracavernosal injection of alprostadil (e.g., alprostadil alfadex; Edex, Viridal) is safe and effective in patients with ED when sildenafil is ineffective. Both of these delivery systems have been used in the treatment of ED. MUSE can also be used in conjunction with a penile constrictor device (e.g., ACTIS).

Клиническое использование

Prostaglandin E1 (PGE1; Alprostadil) is approved for the intracavernosal (Caverject, Edex)or intraurethral suppository (Muse) treatment of ED. A three-drug combination of PGE1, papaverine, and phentolamine sometimes is used as an intracavernosal injection to achieve a synergistic action. Erectile dysfunction that is medication-induced or caused by endocrine problems, such as hypogonadism or hyper- or hypothyroidism, should be evaluated and appropriately treated before PGE1 treatment is considered.

Метаболизм

The major route of excretion of PGE1 metabolites is via the kidney. Its elimination half-life is 5 to 10 minutes. If any alprostadil is systemically absorbed, it is metabolized by a single pass through the lungs. The onset of action is within 10 minutes, and the time to peak effect is less than 20 minutes. The duration of action is 1 to 3 hours for the intracavernosal injection and 30 to 60 minutes for the intraurethral suppository.