Drugs alprostadil

Alprostadil injected into the corpus cavernosum is the more effective form and is the only Food and Drug Administration (FDA)-approved agent for injection. The onset of action is... 

VEDs can be used as second-line therapy after failure of oral or injectable drugs. Adding alprostadil to a VED improves the response rate. 

Drugs that may interact with alprostadil include anticoagulants and vasoactive agents. 

The newer drug of same category are alprostadil, vardenafil and tadalafil which are recently introduced for erectile dysfunction in man. Apomorphine is... 

The drug most commonly used in patients who do not respond to sildenafil is alprostadil, a PGEi analog (see Chapter 18) that can be injected directly into the cavernosa or placed in the urethra as a minisuppository, from which it diffuses into the cavernosal tissue. Phentolamine can be used by injection into the cavernosa. These drugs will cause erection in most men who do not respond to sildenafil. 

Intracavernosal alprostadil was effective and well tolerated in the treatment of erectile dysfunction, according to the results of a 6-month study (funded by Pharmacia Upjohn) in 848 men (mean age 52 years) with at least a 4-month history of erectile dysfunction (12). This is provided that the individual dose is established by titration and patients receive training in injection techniques and periodic supervision during treatment. An initial dose was established for each patient and the patients then administered the alprostadil themselves at home. Of 727 evaluable patients, 682 (94%) had at least one erectile response after the injection of alprostadil, and 88% of injections lead to a satisfactory sexual response. The most commonly reported adverse event was penile pain, reported by 44% of patients, but only after 8% of injections. In just over half of the patients who had penile pain, the condition was reported as mild. Prolonged erection, penile fibrosis, and priapism occurred in 8,4, and 0.9% of patients respectively. Treatment was withdrawn because of medical events in 4% of patients, and drug-related events accounted for treatment withdrawal in 2% of patients. 

Erectile dysfunction Alprostadil injected into the corpus caver-nosum of the penis provides effective treatment of some forms of male impotence. The drug increases arterial inflow through vasodilation and decreases venous outflow by causing relaxation of the corporal smooth muscle that occludes draining venules. Possible side effects include pain at the site of injection and, rarely, prolonged erection. 

Erectile dysfunction, that is, the inability to maintain penile erection for the successful performance of sexual activity, has both organic and psychogenic causes, including as a sequelae to prostatic surgery. Erectile dysfunction is estimated to affect up to 30 million men in the United States. Previous therapies have included penile implants, and intrape-nile injections of alprostadil (see p. 420). Sildenafil [sil DEN a HI], the first oral drug approved for the treatment of erectile dysfunction in males, was introduced in early 1998. 

ANTI HYPERTENSIVES AND HEART FAILURE DRUGS PROSTAGLANDINS -ALPROSTADIL t hypotensive effect Additive hypotensive effect Monitor BP at least weekly until stable. Warn patients to report symptoms of hypotension (light-headedness, dizziness on standing, etc.)... 

ALPROSTADIL - Drugs Used in Obstetrics and Gynaecology, Prostaglandins ... 

Alprostadil (Edex , Schwartz) is a lyophilized product of Prostaglandin Ei in a-cyclodextrin inclusion complex. The complex has better stability and aqueous solubility than the drug itself... 

The vasoactive amines phentolamine and papaverine are occasionally used as intracavernosal therapy, usually in combination with alprostadil, although their use for erectile dysfunction is off-label. Moxisylyte is another vasoactive agent used as intracavernosal therapy. The drug is approved in several European countries, but is not approved in the United States. The advantages over alprostadil are that with moxisylyte, sexual stimulation is still required to achieve full erection and that detumescence occurs on ejaculation. 

The enhanced efficacy of the intracavernosal inj ection may be related to the excellent bioavailability of the drug when injected directly into the corpora cavernosum. In contrast, intraurethral alprostadil doses generally are several hundred times larger than intracavernosal doses. Intraurethral alprostadil must be absorbed from the urethra. 

Both formulations of alprostadil are considered more invasive than VEDs or phosphodiesterase inhibitors. For this reason, intracavernosal alprostadil is generally prescribed after patients fail to respond to or cannot use the less invasive interventions. Intracavernosal alprostadil is preferred over intraurethral alprostadil because the former is more effective than the latter. Also, intracavernosal alprostadil may be preferred in patients with diabetes mellitus, who are accustomed to injectable drug therapy and may suffer from peripheral neuropathies, which decreases the patient s perception of pain upon injection. Intraurethral alprostadil is generally reserved as a treatment of last resort for patients who fail other less invasive and more effective forms of therapy and also refuse surgery. 

Intracavernosal injection should be made into one corpus cavernosum only. From this injection site, the drug will reach the other corpus cavernosum through vascular communications between the two corpora. Alprostadil acts rapidly, with an onset in 5 to 15 minutes. The duration is directly related to the dose, and within the usual dosage range of 2.5 to 20 meg, the duration of the erection lasts no more than 1 hour. Local enzymes in the corpora cavernosum quickly metabolize alprostadil. Any alprostadil that escapes into the systemic circulation is deactivated on first passage through the lungs. Hence the plasma half-life of alprostadil is approximately 1 minute. Also, dose modification is not necessary in patients with renal or hepatic diseases. 

Although combinations of proerectogenic drugs may be used in some patients (e.g., sildenafil plus alprostadil intracaver-nosal injection), such combinations are not recommended by the FDA and may lead to prolonged erections and priapism. 

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