Tadalafil

INTRODUCTION

Indications

Erectile dysfunction.

Action

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.

Interventions

• To minimize orthostatic hypotension, patient should move slowly when assuming a more upright position.

Patient/Client-Related Instruction

• 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.

Pharmacokinetics

Absorption: Well absorbed following oral administration.

Distribution: Extensive tissue distribution; penetrates semen.

Protein Binding: 94%.

Metabolism and Excretion: Mostly metabolized by the liver (mainly CYP3A4 enzyme system); metabolites are excreted in feces (61%) and urine (36%).

Half-life: 17.5 hr.

Contraindications/Precautions

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, or leukemia; ...