Pharmacologic: phosphodiesterase type 5 inhibitors
Increases cyclic guanosine monophosphate (cGMP) levels by inhibiting phosphodiesterase type 5 (PDE5), an enzyme responsible for the breakdown of cGMP. cGMP produces smooth muscle relaxation of the corpus cavernosum, which in turn promotes increased blood flow and subsequent erection. Therapeutic Effects: Enhanced blood flow to the corpus cavernosum and erection sufficient to allow sexual intercourse. Requires sexual stimulation.
Adverse Reactions/Side Effects
CNS: headache. EENT: HEARING LOSS, VISION LOSS, nasal congestion. CV: hypotension. GI: dyspepsia. GU: priapism. Derm: flushing. MS: back pain, limb pain, myalgia.
PHYSICAL THERAPY IMPLICATIONS
Examination and Evaluation
Be alert for sudden loss of vision or hearing, and seek emergency care for any changes in vision or hearing.
Assess blood pressure periodically and compare to normal values (See Appendix F). Report low blood pressure (hypotension), especially if patient experiences dizziness, fatigue, or other symptoms.
Assess any muscle, back, or limb pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.
Instruct patient to notify health care professional promptly if erection lasts longer than 4 hr or if they experience a sudden decrease or loss of vision or hearing.
Instruct patient to report other bothersome side effects such as severe or prolonged headache, nasal congestion, skin flushing, or indigestion.
Absorption: Well absorbed following oral administration.
Distribution: Extensive tissue distribution; penetrates semen.
Metabolism and Excretion: Mostly metabolized by the liver (mainly CYP3A4 enzyme system); metabolites are excreted in feces (61%) and urine (36%).
Contraindicated in: Hypersensitivity; Concurrent use of nitrates; Unstable angina, recent history of stroke, life-threatening heart failure within 6 mo, uncontrolled hypertension, arrhythmias, stroke within 6 mo, or MI within 90 days; Any other cardiovascular pathology precluding sexual activity; Known hereditary degenerative retinal disorders; Severe hepatic impairment; Congenital or acquired QT prolongation or concurrent use of class IA or III antiarrhythmics; Pedi: Women, children, or newborns.
Use Cautiously in: Left ventricular outflow obstruction; Penile deformity; Underlying conditions predisposing to priapism, including sickle cell anemia, multiple myeloma, ...