Formulary
Tadalafil: Indications, Dosing, Side Effects and Interactions
Tadalafil clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 5 min read
Tadalafil: Indications, Dosing, Side Effects and Interactions
Tadalafil clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Pulmonary arterial hypertension (initiated under specialist supervision)**
- **Adult** (By Mouth): 40 mg once daily.
**Erectile dysfunction**
- **Adult** (By Mouth): Initially 10 mg (max. per dose 20 mg), to be taken at least 30 minutes before sexual activity, subsequent doses adjusted according to response, the effect of intermittent dosing may persist for longer than 24 hours, continuous daily use not recommended; maximum 1 dose per day.
**Erectile dysfunction;**
- **Adult** (By Mouth): for patients who anticipate sexual activity at least twice a week 5 mg once daily, reduced to 2.5 mg once daily, adjusted according to response.
**Benign prostatic hyperplasia**
- **Adult** (By Mouth): 5 mg once daily.
Cautions
When used for Benign prostatic hyperplasia Anatomical deformation of the penis (e.g. angulation, cavernosal fibrosis, Peyronie's disease); cardiovascular disease; left ventricular outflow obstruction; predisposition to priapism (e.g. in sickle-cell disease, multiple myeloma, or leukaemia) When used for Erectile dysfunction Anatomical deformation of the penis (e.g. angulation, cavernosal fibrosis, Peyronie's disease); cardiovascular disease; left ventricular outflow obstruction; predisposition to priapism (e.g. in sickle-cell disease, multiple myeloma, or leukaemia) When used for Pulmonary arterial hypertension Anatomical deformation of the penis; aortic and mitral valve disease; congestive cardiomyopathy; coronary artery disease; hereditary degenerative retinal disorders; left ventricular dysfunction; life-threatening arrhythmias; pericardial constriction; predisposition to priapism; pulmonary veno-occlusive disease; uncontrolled hypertension Cautions, further information Elderly For phosphodiesterase type-5 inhibitors, Screening Tool of Older Persons' potentially inappropriate Prescriptions (STOPP) criteria to aid medication reviews (see Prescribing in the elderly for information): potentially inappropriate in severe heart failure characterised by hypotension i.e. systolic blood pressure less than 90 mmHg, or concurrent nitrate therapy for angina (risk of cardiovascular collapse).
Contraindications
General contra-indications: Acute myocardial infarction in past 90 days; history of non-arteritic anterior ischaemic optic neuropathy; hypotension (avoid if systolic blood pressure below 90 mmHg) Specific contra-indications: When used for Benign prostatic hyperplasia Mild to severe heart failure; patients in whom vasodilation or sexual activity are inadvisable; recent stroke; uncontrolled arrhythmias; uncontrolled hypertension; unstable angina When used for Erectile dysfunction Mild to severe heart failure; patients in whom vasodilation or sexual activity are inadvisable; recent stroke; uncontrolled arrhythmias; uncontrolled hypertension; unstable angina
Side effects
Common or very common Flushing; gastrointestinal discomfort; headaches; myalgia; nasal congestion; pain Uncommon Arrhythmias; chest pain; dizziness; dyspnoea; eye pain; fatigue; gastrooesophageal reflux disease; haemorrhage; hypertension; hypotension; nausea; oedema; palpitations; skin reactions; tinnitus; vision disorders; vomiting Rare or very rare Acute coronary syndrome; angioedema; cerebrovascular insufficiency; eye erythema; eye swelling; haematospermia; hyperhidrosis; memory loss; optic neuropathy (discontinue if sudden visual impairment occurs); priapism; retinal occlusion; seizure; Stevens-Johnson syndrome; sudden cardiac death; sudden hearing loss (discontinue drug and seek medical advice); syncope
Interactions
**Severe interactions:**
- Thus, in a patient prescribed any dose of tadalafil (2.5 mg - 20 mg), where nitrate administration is deemed medically necessary in a life-threatening situation, at least 48 hours should have...
- Anti-hypertensives (including calcium channel blockers) The co-administration of doxazosin (4 and 8 mg daily) and tadalafil (5 mg daily dose and 20 mg as a single dose) increases the blood...
- Tadalafil (10 mg except for studies with angiotensin II receptor blockers and amlodipine in which a 20 mg dose was applied) had no clinically significant interaction with any of these classes.
- Cytochrome P450 metabolised medicinal products Tadalafil is not expected to cause clinically significant inhibition or induction of the clearance of medicinal products metabolised by CYP450 isoforms.
- R-warfarin) Tadalafil (10 mg and 20 mg) had no clinically significant effect on exposure (AUC) to S-warfarin or R-warfarin (CYP2C9 substrate), nor did tadalafil affect changes in prothrombin time...
**Other interactions (33):**
- Interaction studies were conducted with 10 mg and/or 20 mg tadalafil, as indicated below.
- With regard to those interaction studies where only the 10 mg tadalafil dose was used, clinically relevant interactions at higher doses cannot be completely ruled out.
- Effects of other substances on tadalafil Cytochrome P450 inhibitors Tadalafil is principally metabolised by CYP3A4.
- A selective inhibitor of CYP3A4, ketoconazole (200 mg daily), increased tadalafil (10 mg) exposure (AUC) 2-fold and C max by 15 %, relative to the AUC and C max values for tadalafil alone.
- Ketoconazole (400 mg daily) increased tadalafil (20 mg) exposure (AUC) 4-fold and C max by 22 %.
- Ritonavir, a protease inhibitor (200 mg twice daily), which is an inhibitor of CYP3A4, CYP2C9, CYP2C19, and CYP2D6, increased tadalafil (20 mg) exposure (AUC) 2-fold with no change in C max .
Pregnancy
Manufacturer advises avoid.
Breast feeding
Manufacturer advises avoid-present in milk in animal studies.
Hepatic impairment
When used for Pulmonary arterial hypertension: Manufacturer advises caution in mild to moderate impairment (limited information available); avoid in severe impairment (no information available). When used for Benign prostatic hyperplasia or Erectile dysfunction: Manufacturer advises caution for regular once-daily dosing (no information available), and in severe impairment for intermittent use (limited information available) . Dose adjustments When used for Pulmonary arterial hypertension: Manufacturer advises consider initial dose reduction to 20 mg once daily in mild to moderate impairment. When used for Erectile dysfunction: Manufacturer advises dose of 10 mg for intermittent use (no information available for higher doses).
Renal impairment
When used for Pulmonary arterial hypertension: Avoid in severe impairment. M When used for Erectile dysfunction or Benign prostatic hyperplasia: Avoid regular once-daily dosing in severe impairment. M Dose adjustments When used for Pulmonary arterial hypertension: Initial dose of 20 mg once daily in mild-to-moderate impairment; dose may be increased to 40 mg once daily if tolerated. M When used for Erectile dysfunction: Maximum dose of 10 mg for intermittent use in severe impairment. M
Medicinal forms
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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