Tadalafil

Trade Names:
Cialis
- Tablets 2.5 mg
- 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

Tadalafil exposure (AUC) doubled in subjects with CrCl 31 to 80 mL/min. In patients with end-stage renal disease on hemodialysis, there was a 2-fold increase in C _max and 2.7- to 4.1-fold increase in AUC. Dosage adjustments are required.

Tadalafil exposure (AUC) in patients with mild or moderate hepatic impairment was comparable with exposure in healthy subjects. There are insufficient data for subjects with severe hepatic impairment.

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

Indications and Usage

Treatment of erectile dysfunction.

Contraindications

Administration with nitrates.

Dosage and Administration

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 once per day for most patients.

Start with 2.5 mg once daily, taken at approximately the same time each day, without regard to timing of sexual activity. The dose may be increased to 5 mg daily, based on individual efficacy and tolerability.

PO

No dosage adjustment is required.

Start with 5 mg not more than once a day (max, 10 mg every 48 h).

Max recommended dosage is 5 mg every 72 h.

No dosage adjustment is required.

Once daily use is not recommended.

PO

Use with caution. Dosage should not exceed 10 mg daily.

Use is not recommended.

Not extensively evaluated. Use with caution.

Use is not recommended.

PO

Patients should be stable on alpha-blocker therapy prior to starting tadalafil. Tadalafil should be started at the lowest recommended dose.

Max recommended dose is 10 mg, not to exceed once every 72 h.

Max dose should not exceed 2.5 mg.

General Advice

• May be taken without regard to food.

Storage/Stability

Store at 59° to 86°F.

Drug Interactions

Decreased BP may occur. Risk of orthostatic signs and symptoms, including increased heart rate, decreased standing BP, dizziness, and headache, may be increased.

Additive effects on BP should be anticipated. Use with caution.

Decreased BP may occur.

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

Tadalafil plasma concentrations may be elevated, increasing the risk of adverse reactions. The tadalafil dosage should not exceed 10 mg once every 72 h for as-needed use or 2.5 mg daily for once-daily use.

Coadministration is contraindicated.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Flushing, hypertension (3%); angina pectoris, chest pain, hypotension, MI, palpitations, postural hypotension, syncope, tachycardia (less than 2%); stroke, sudden cardiac death (postmarketing).

CNS

Headache (15%); asthenia, dizziness, fatigue, hypesthesia, insomnia, paresthesia, somnolence, vertigo (less than 2%); migraine, seizure and seizure recurrence, transient global amnesia (postmarketing).

Dermatologic

Pruritus, rash, sweating (less than 2%); exfoliative dermatitis, Stevens-Johnson syndrome, urticaria (postmarketing).

EENT

Nasopharyngitis (6%); nasal congestion (4%); blurred vision, changes in color vision, conjunctivitis including conjunctival hyperemia, epistaxis, eye pain, increased lacrimation, pharyngitis, sudden decrease or loss of hearing, swelling of eyelids, tinnitus (less than 2%); non-arteritic anterior ischemic optic neuropathy, retinal artery occlusion, retinal vein occlusion, visual field defect (postmarketing).

GI

Dyspepsia (10%); viral gastroenteritis (5%); diarrhea, gastroesophageal reflux (3%); dry mouth, dysphagia, esophagitis, gastritis, increased gamma-glutamyl transpeptidase, loose stools, nausea, upper abdominal pain, vomiting (less than 2%).

Genitourinary

UTI (2%); increased erection, spontaneous penile erection (less than 2%); priapism (postmarketing).

Hepatic

Abnormal LFTs (less than 2%).

Musculoskeletal

Back pain (6%); myalgia (4%); limb pain; pain in extremities (2%); arthralgia, neck pain (less than 2%).

Respiratory

Cough, upper respiratory tract infection (4%); bronchitis (2%); dyspnea (less than 2%).

Miscellaneous

Influenza (5%); abdominal pain (2%); face edema, pain (less than 2%).

Precautions

Pregnancy

Category B .

Lactation

Undetermined.

Children

Safety and efficacy not established.

Elderly

No dosage adjustments are needed based on age alone.

Renal Function

Dosage adjustment may be needed in patients with renal impairment who are taking tadalafil on an as-needed basis. Once daily use is not recommended.

Hepatic Function

Dosage adjustment may be needed in patients with hepatic impairment who are taking tadalafil on an as-needed basis. Caution is advised for once daily use. Once daily use is not recommended in patients with severe hepatic impairment.

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, or hereditary degenerative retinal disorder (eg, retinitis pigmentosa).

CV risk

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

Hearing loss

Sudden decrease or loss of hearing, which may be accompanied by tinnitus and dizziness, has been reported.

Other erectile dysfunction therapy

Combined use with tadalafil is not recommended.

Priapism

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

Vision

Sudden decrease in or loss of vision in one or both eyes has been reported in postmarketing experience. Visual loss may be permanent.

Overdosage

Symptoms

Adverse events following a single oral dose of up to 500 mg to healthy subjects were similar to those seen with lower doses.

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: chest pain, dizziness, erection persisting longer than 4 h, fainting, painful erection, ringing in the ears, vision changes.
• Caution patient to limit alcohol intake while using tadalafil.
• Caution patient regarding concurrent use of nitrates and alpha blockers (except tamsulosin 0.4 mg every day).
• 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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