Because of the potential for symptomatic hypotension and syncope, which occurred in 3% and 0.4%, respectively, of patients during in-clinic dosing, MUSE titration should be carried out under medical supervision. During post-marketing surveillance syncope occurring within one hour of administration has been reported. Patients should be cautioned to avoid activities, such as driving or hazardous tasks, where injury could result if hypotension or syncope were to occur after MUSE administration.
A complete medical history and physical examination should be undertaken to exclude reversible causes of erectile dysfunction prior to the initiation of MUSE therapy. In addition, underlying disorders that might preclude the use of MUSE (see CONTRAINDICATIONS) should be sought.
- Cardiovascular effects: During in-clinic dosing, patients should be monitored for symptoms of hypotension, and the lowest effective dose of MUSE should be prescribed.
- Hematologic effects: Patients administering MUSE improperly may be at risk of urethral abrasion resulting in minor bleeding or spotting. Patients on anticoagulant therapy or with bleeding disorders may be at higher risk of bleeding. Patients on anticoagulant therapy have been safely treated with MUSE; however, the risk/benefit ratio in these patients should be considered prior to prescribing MUSE.
- Resumption of sexual activity: Sexual intercourse is considered a vigorous physical activity, and it increases heart rate as well as cardiac work. Physicians may want to examine the cardiac fitness of patients prior to treating erectile dysfunction.
- Priapism and prolonged erection: In clinical trials of MUSE, priapism (rigid erection lasting >/=6 hours) and prolonged erection (rigid erection lasting 4 hours and <6 hours) were reported infrequently (<0.1% and 0.3% of patients, respectively). Nevertheless, these events are a potential risk of pharmacologic therapy and can cause penile injury. Physicians should lower the dose or consider discontinuing MUSE treatment in any patient who develops priapism or prolonged erection.
- Drug-Drug Interactions: Because there are low or undetectable (<2 picograms/mL) amounts of alprostadil found in the peripheral venous circulation following MUSE administration, systemic drug-drug interactions with MUSE are unlikely. Although formal studies have not been conducted, the concomitant use of MUSE and anti-hypertensive medications may increase the risk of hypotension. It is therefore advised that caution be used in the administration of MUSE to individuals on anti-hypertensive medications. In addition, the presence of medications in the circulation that attenuate erectile function may influence the response to MUSE.
- Drug-Device Interactions: Use of MUSE in patients with penile implants has not been studied.
- Sexual Preference: There is no experience in homosexual men and no experience with other than vaginal intercourse.
Information for Patients: Patients should be informed that MUSE offers no protection from the transmission of sexually transmitted diseases. Patients and partners who use MUSE need to be counseled about the protective measures that are necessary to guard against the spread of sexually transmitted agents, including the human immunodeficiency virus (HIV).
Although unreported in clinical trials, there is the possibility that an overdosage of MUSE can cause priapism, a painful erection of the penis sustained for hours and unrelieved by sexual intercourse or masturbation. This condition is serious and, if untreated, it can lead to permanent inability to have an erection. Patients who experience a prolonged erection should seek prompt medical attention.
Patients should be instructed how to administer MUSE. A patient package insert must be given to each patient at the initiation of MUSE therapy.
Information for Partners: Partners of patients using MUSE should be informed that MUSE offers no protection from the transmission of sexually transmitted diseases. Patients and partners who use MUSE should be counseled about the protective measures that are necessary to guard against the spread of sexually transmitted agents, including the human immunodeficiency virus (HIV). Human semen contains PGE1, but additional amounts may be present from MUSE administration (see CLINICAL PHARMACOLOGY). Partners who have experienced an extended period of sexual abstinence should be encouraged to seek advice from a health care professional prior to resuming sexual intercourse. The use of a water-based lubricant may facilitate vaginal penetration.
It is recommended that couples using MUSE employ adequate contraception if the female partner is of childbearing potential. There is no information on the effects on early pregnancy of PGE1 at the levels received by female partners. MUSE has no contraceptive properties. MUSE should not be used if the female partner is pregnant, unless the couple uses a condom barrier.
Carcinogenesis, Mutagenesis, Impairment of Fertility: Long-term carcinogenicity studies of alprostadil have not been conducted. Alprostadil showed no evidence of mutagenicity in vitro in the Ames bacterial reverse mutation test, the unscheduled DNA synthesis assay in rat hepatocytes, or the Chinese hamster ovary forward gene mutation assay; nor was there evidence of mutagenicity in vivo in the mouse micronucleus assay. Alprostadil concentrations increased chromosomal aberrations above control incidence in the in vitro Chinese hamster ovary chromosomal aberration assay.
In dogs, sperm concentration, morphology, and motility were unaffected by daily intraurethral administration of up to 3000 mcg MUSE (alprostadil) for 13 weeks (200 mcg/kg/day or about 3.5 times the maximum recommended daily dose adjusted for body surface area). Alprostadil concentrations of 400 mcg/mL had no effect on human sperm motility or viability in vitro.
Pregnancy: Pregnancy Category C: Alprostadil has been shown to be embryotoxic (decreased fetal weight) when administered as a subcutaneous bolus to pregnant rats at doses as low as 500 mcg/kg/day. Doses of 2000 mcg/kg/day resulted in increased resorptions, reduced numbers of live fetuses, increased incidences of visceral and skeletal variations (primarily left umbilical artery and generalized reduction in ossification of the entire skeleton) and gross visceral and skeletal malformations (primarily edema, hydrocephaly, anophthalmia/microphthalmia, and skeletal anomalies). The latter dose produced maternal toxicity (ataxia, lethargy, diarrhea, and retarded body weight gain). When administered by continuous intravenous infusion, evidence of embryotoxicity (decreased fetal weight gain and increased incidence of hydroureter) was observed at 2000 mcg/kg/day, a dose that was also associated with a decrease in maternal weight gain. Intravaginal administration of up to 4000 mcg/day of MUSE (alprostadil) to pregnant
rabbits (1100 mcg/kg/day or about 12.5 times the maximum recommended daily dose adjusted for body surface area) resulted in no evidence of harm to the fetus. MUSE should not be used for sexual intercourse with a pregnant woman unless the couple uses a condom barrier.
Nursing Mothers and Pediatric Use: MUSE is not indicated for use in newborns, children, or women.