A-Z Drug Facts > Tadalafil

Tadalafil

Pronouncation: (tah-DAH-lah-fil)
Class: Phosphodiesterase type 5 inhibitor

Trade Names:
Cialis
- Tablets 5 mg
- Tablets 10 mg
- Tablets 20 mg

Pharmacology

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Enhances the effect of nitric oxide at the nerve ending and endothelial cells in the corpus cavernosum by inhibiting phosphodiesterase type 5 in the corpus cavernosum of the penis. This results in vasodilation, increased inflow of blood into the corporus cavernosum, and ensuing penile erection upon sexual stimulation.

Pharmacokinetics

Absorption

Bioavailability undetermined; T _max is 30 min to 6 h (median 2 h).

Distribution

Vd of tadalafil is approximately 63 L, and it is 94% protein bound.

Metabolism

Predominantly metabolized by CYP3A4 to a catechol metabolite, which undergoes further metabolism to the major circulating metabolite, a methylcatechol glucuronide.

Elimination

Mean oral Cl is 2.5 L/h and the mean t _½ is 17.5 h. Tadalafil is excreted predominantly as metabolites, mainly in the feces (approximately 61%) and to a lesser degree in the urine (about 36%).

Special Populations

Elderly

Subjects over 65 yr have a 25% higher exposure compared with subjects 19 to 45 yr; however, no dosage adjustment is warranted based on age alone.

Indications and Usage

Treatment of erectile dysfunction.

Contraindications

Administration with nitrates and nitric oxide donors, alpha-blockers (except 0.4 mg/day tamsulosin); hypersensitivity to any component of the product.

Dosage and Administration

Adults

PO 10 mg prior to anticipated sexual activity. The dose may be titrated to 5 or 20 mg based on efficacy and tolerability. The max recommended frequency is every day for most patients.

Renal Insufficiency
Adults

PO Mild renal insufficiency: No dosage adjustment is required. Moderate renal insufficiency (CrCl 31 to 50 mL/min): Start with 5 mg not more than every day (max, 10 mg every 48 h). Severe renal insufficiency (CrCl less than 30 mL/min) on hemodialysis: Max recommended dose is 5 mg.

Hepatic Impairment
Adults

PO Mild to moderate hepatic impairment: Dose should not exceed 10 mg every day. Severe hepatic impairment: Use is not recommended.

Storage/Stability

Store tablets at controlled room temperature (59° to 86°F).

Drug Interactions

Alpha-blockers (eg, terazosin), nitrates

Coadministration of these agents with tadalafil is contraindicated (except 0.4 mg/day tamsulosin).

CYP3A4 inducers (eg, carbamazepine, phenytoin, rifampin)

Plasma levels may be decreased, reducing tadalafil exposure; however, no dosage adjustment is warranted.

CYP3A4 inhibitors (eg, ketoconazole, ritonavir)

Plasma levels of tadalafil may be elevated, increasing the risk of side effects and necessitating dosage adjustment. Do not exceed 10 mg once every 72 h.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Angina pectoris, chest pain, hypotension, MI, postural hypotension, palpitation, syncope, tachycardia (less than 2%).

CNS

Headache (15%); fatigue, dizziness, hypesthesia, insomnia, paresthesia, somnolence, vertigo (less than 2%).

Dermatologic

Pruritus, rash, sweating (less than 2%).

EENT

Nasal congestion (3%); blurred vision, changes in color vision, conjunctivitis (including hyperemia), eye pain, increased lacrimation, swelling of eyelids (less than 2%).

GI

Dyspepsia (10%); diarrhea, dry mouth, dysphagia, esophagitis (less than 2%).

Genitourinary

Increased erection, spontaneous penile erection (less than 2%).

Hepatic

Abnormal LFTs (less than 2%).

Musculoskeletal

Myalgia (4%); arthralgia, neck pain (less than 2%).

Respiratory

Epistaxis, pharyngitis (less than 2%).

Miscellaneous

Back pain (6%); limb pain, flushing (3%); asthenia, face edema, pain (less than 2%).

Precautions

Pregnancy

Category B .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Renal Function

Dosage adjustment may be needed.

Hepatic Function

Dosage adjustment may be needed.

Special Risk Patients

Because there are no clinical data on safety and efficacy, use is not recommended in patients with unstable angina or angina occurring during sexual intercourse, MI within last 90 days, New York Heart Association Class II or greater heart failure in last 6 mo, uncontrolled arrhythmias, hypotension, uncontrolled hypertension, stroke within last 6 mo, hereditary degenerative retinal disorder (eg, retinitis pigmentosa).

CV risk

CV status and left ventricular outflow obstruction (eg, aortic stenosis) should be evaluated before treatment.

Priapism

Prolonged erections, exceeding 4 h, may occur and require immediate medical attention.

Patient Information

• Instruct patient to read the patient information leaflet before starting therapy and with each refill.
• Advise patient that medication may be most effective if taken approximately 60 min before anticipated sexual activity, but that medication can be taken anywhere from 30 min to 4 h before sexual activity.
• Advise patient to take prescribed dose at least 30 min before anticipated sexual activity.
• Advise patient to take each dose without regard to meals but to take with food if stomach upset occurs.
• Advise patient that sexual stimulation will be required for medication to work and an erection to occur.
• Caution patient not to increase the dose or frequency of use unless advised by health care provider.
• Advise patient to contact health care provider if unsatisfied with sexual performance after taking medication or if bothersome side effects occur.
• Instruct patient to stop using and contact health care provider immediately if any of the following occur: dizziness, fainting, chest pain, vision changes, erection persisting longer than 4 h, painful erection.
• Caution patient to limit alcohol intake while using tadalafil.
• Caution patient regarding concurrent use of nitrates and alpha-blockers (except 0.4 mg every day tamsulosin).
• Caution patient to avoid using “poppers” (eg, amyl nitrate, butyl nitrate) while taking this medication.
• Caution patient that medication is not a male form of birth control nor does it provide protection against sexually transmitted diseases and to use protective measures as indicated.

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