Drug reference

Tadalafil

Vasodilator · Erectile dysfunction agent, Pulmonary arterial hypertension agent, Benign prostatic hyperplasia agent

Also known as Adcirca, Cialis, Talmanco

VasodilatorErectile dysfunction agent, Pulmonary arterial hypertension agent, Benign prostatic hyperplasia agent

CDSCO approvedSchedule H

EXCRETION

—

not curated

INTERACTIONS

12 major

incl. contraindicated

PREGNANCY

Not indicated in women; avoid

FDA category + note

Top interactionssee all 12 →

Isosorbide DinitrateContraindicatedTextbook-citedKDT 7e · p950
Isosorbide MononitrateContraindicatedTextbook-citedKDT 7e · p950
NitroglycerinContraindicatedTextbook-citedKDT 7e · p950
Guanylate Cyclase StimulatorsContraindicatedTextbookG&G 14e · p700

Mechanism

Tadalafil is a selective phosphodiesterase type 5 (PDE5) inhibitor that prevents the degradation of cyclic guanosine monophosphate (cGMP) in corpus cavernosum smooth muscle, potentiating the vasodilatory effect of nitric oxide released during sexual stimulation. Its distinguishing feature is a plasma half-life of ~17.5 hours — 4-5 times longer than sildenafil (~4 hours) — enabling a 36-hour window of efficacy and once-daily dosing for both erectile dysfunction and benign prostatic hyperplasia. It also has selectivity for PDE11, which is expressed in prostate, testes, and skeletal muscle.

Indications

Pulmonary arterial hypertension (initiated under specialist supervision)Erectile dysfunctionErectile dysfunction; for patients who anticipate sexual activity at least twice a weekBenign prostatic hyperplasiapulmonary hypertensionPAHmoderate PAH (functional class II–III)erectile dysfunction (ED)

Dosing

Adult: ED (intermittent): 10 mg at least 30 min before activity, max 20 mg, max 1 dose/day. ED (daily): 2.5-5 mg OD. BPH: 5 mg OD. PAH: 40 mg OD.
Renal adjustment: CrCl 31-80: max 10 mg/48h (intermittent). CrCl <30: avoid (intermittent); max 5 mg daily with caution.
Hepatic adjustment: Max 10 mg; avoid in severe impairment
Geriatric: No specific adjustment; assess cardiovascular fitness
Max dose: 20 mg/dose (ED); 40 mg/day (PAH); 5 mg/day (BPH)

Pharmacokinetics

Peak effect

30–120 min

Duration

24–36 hours

Half-life

longer half-life than sildenafil

Bioavailability

—

Protein binding

94%

Excretion

—

Contraindications

MI in past 90 days
Systolic BP <90 mmHg
History of NAION
Concurrent nitrate use
Concurrent use of potent CYP3A4 inhibitors for PAH indication
patients taking nitrates (for up to 3 days after tadalafil)
coronary heart disease
liver disease (caution)
kidney disease (caution)
peptic ulcer (caution)
bleeding disorders (caution)
leukaemia (caution, predisposes to priapism)
sickle cell anaemia (caution, predisposes to priapism)
myeloma (caution, predisposes to priapism)
Use within 48 hours of nitroglycerin administration

Side effects

Common

HeadacheFlushingNasal congestionDyspepsiaMyalgiaBack painbluish hazelight sensitivityvisual disturbances (less frequent than sildenafil)

Serious

Priapism
Non-arteritic anterior ischaemic optic neuropathy (NAION)
Sudden hearing loss
Angioedema
Stevens-Johnson syndrome
toxic skin reactions (Stevens-Johnson syndrome and exfoliative dermatitis)

Pregnancy & lactation

Pregnancy

Not indicated in women; avoid

Drug interactions

Isosorbide Dinitrate

Contraindicated

Textbook-cited

Precipitous and potentially fatal fall in blood pressure; myocardial ischemia

Concurrent use is absolutely contraindicated

Source: KDT 7e · p950

Isosorbide Mononitrate

Contraindicated

Textbook-cited

Precipitous and potentially fatal fall in blood pressure; myocardial ischemia

Concurrent use is absolutely contraindicated

Source: KDT 7e · p950

Nitroglycerin

Contraindicated

Textbook-cited

Precipitous and potentially fatal fall in blood pressure; myocardial ischemia

Concurrent use is absolutely contraindicated

Source: KDT 7e · p950

Guanylate Cyclase Stimulators

Contraindicated

Textbook

Not explicitly detailed, but implied severe hypotension.

Tadalafil is contraindicated with concurrent guanylate cyclase stimulators.

Source: G&G 14e · p700

Nitrates

Contraindicated

Textbook

Precipitous fall in blood pressure; myocardial infarction (MI) can occur.

Nitrates are contraindicated for up to 3 days after tadalafil use.

Source: KDT 7e · p304

Organic Nitrates

Contraindicated

Textbook

Dangerously low blood pressures.

The administration of PDE5 inhibitors to patients receiving organic nitrates is contraindicated. The patient’s underlying cardiovascular status and concurrent use of hypotensive agents (e.g., nitrates, α adrenergic antagonists) must be considered prior to use of this class of drugs.

Source: G&G 14e · p999

Sildenafil

Contraindicated

Textbook

Extreme hypotension, potentially life-threatening.

PDE5 inhibitors should not be prescribed to patients receiving any form of nitrate. Patients should be warned not to use PDE5 inhibitors and nitrates concurrently. A period longer than 24 hours (especially with tadalafil) may be needed following administration of a PDE5 inhibitor for safe use of nitrates. If significant hypotension occurs, fluids and α adrenergic receptor agonists may be used for support.

Source: G&G 14e · p612

Isosorbide

Contraindicated

Database

Dangerous hypotension

Absolute contraindication.

Source: DDInter

Nicorandil

Contraindicated

Database

Profound and prolonged systemic hypotension, syncope, myocardial ischemia, and even death.

Concomitant use is absolutely contraindicated. Patients on nicorandil should not be prescribed tadalafil or other PDE5 inhibitors (sildenafil, vardenafil).

Amyl Nitrite

Severe

Database

Drug interaction classified as: synergy

Source: DDInter

Boceprevir

Severe

Database

Drug interaction classified as: metabolism

Source: DDInter

Clarithromycin

Severe