Tadalafil

7 DRUG INTERACTIONS Tadalafil can potentiate the hypotensive effects of nitrates, alpha-blockers, antihypertensives or alcohol ( 7.1 ). CYP3A4 inhibitors (e.g. ketoconazole, ritonavir) increase tadalafil exposure ( 2.7 , 5.10 , 7.2 ) requiring dose adjustment: Tadalafil for use as needed: no more than 10 mg every 72 hours Tadalafil for once daily use: dose not to exceed 2.5 mg CYP3A4 inducers (e.g. rifampin) decrease tadalafil exposure ( 7.2 ). 7.1 Potential for Pharmacodynamic Interactions with Tadalafil Nitrates — Administration of tadalafil to patients who are using any form of organic nitrate, is contraindicated. In clinical pharmacology studies tadalafil was shown to potentiate the hypotensive effect of nitrates. In a patient who has taken tadalafil, where nitrate administration is deemed medically necessary in a life-threatening situation, at least 48 hours should elapse after the last dose of tadalafil before nitrate administration is considered. In such circumstances, nitrates should still only be administered under close medical supervision with appropriate hemodynamic monitoring [see Dosage and Administration ( 2.7 ), Contraindications ( 4.1 ), and Clinical Pharmacology ( 12.2 )] . Alpha-Blockers — Caution is advised when PDE5 inhibitors are coadministered with alpha-blockers. PDE5 inhibitors, including tadalafil, and alpha-adrenergic blocking agents are both vasodilators with blood-pressure-lowering effects. When vasodilators are used in combination, an additive effect on blood pressure may be anticipated. Clinical pharmacology studies have been conducted with coadministration of tadalafil with doxazosin, tamsulosin or alfuzosin. [see Dosage and Administration ( 2.7 ), Warnings and Precautions ( 5.6 ), and Clinical Pharmacology ( 12.2 )] . Antihypertensives — PDE5 inhibitors, including tadalafil, are mild systemic vasodilators. Clinical pharmacology studies were conducted to assess the effect of tadalafil on the potentiation of the blood-pressure-lowering effects of selected antihypertensive medications (amlodipine, angiotensin II receptor blockers, bendrofluazide, enalapril, and metoprolol). Small reductions in blood pressure occurred following coadministration of tadalafil with these agents compared with placebo. [see Warnings and Precautions ( 5.6 ) and Clinical Pharmacology ( 12.2 )] . Alcohol — Both alcohol and tadalafil, a PDE5 inhibitor, act as mild vasodilators. When mild vasodilators are taken in combination, blood-pressure-lowering effects of each individual compound may be increased. Substantial consumption of alcohol (e.g., 5 units or greater) in combination with tadalafil can increase the potential for orthostatic signs and symptoms, including increase in heart rate, decrease in standing blood pressure, dizziness, and headache. Tadalafil did not affect alcohol plasma concentrations and alcohol did not affect tadalafil plasma concentrations. [see Warnings and Precautions ( 5.9 ) and Clinical Pharmacology ( 12.2 )] . 7.2 Potential for Other Drugs to Affect Tadalafil [See Dosage and Administration ( 2.7 ) and Warnings and Precautions ( 5.10 )] . Antacids — Simultaneous administration of an antacid (magnesium hydroxide/aluminum hydroxide) and tadalafil reduced the apparent rate of absorption of tadalafil without altering exposure (AUC) to tadalafil. H2 Antagonists (e.g. Nizatidine ) — An increase in gastric pH resulting from administration of nizatidine had no significant effect on pharmacokinetics. Cytochrome P450 Inhibitors — Tadalafil is a substrate of and predominantly metabolized by CYP3A4. Studies have shown that drugs that inhibit CYP3A4 can increase tadalafil exposure. CYP3A4 (e.g., Ketoconazole) — Ketoconazole (400 mg daily), a selective and potent inhibitor of CYP3A4, increased tadalafil 20 mg single-dose exposure (AUC) by 312% and Cmax by 22%, relative to the values for tadalafil 20 mg alone. Ketoconazole (200 mg daily) increased tadalafil 10-mg single-dose exposure (AUC) by 107% and Cmax by 15%, relative to the values for tadalafil 10 mg alone [see Dosage and Administration ( 2.7 )] . Although specific interactions have not been studied, other CYP3A4 inhibitors, such as erythromycin, itraconazole, and grapefruit juice, would likely increase tadalafil exposure. HIV Protease inhibitor — Ritonavir (500 mg or 600 mg twice daily at steady state), an inhibitor of CYP3A4, CYP2C9, CYP2C19, and CYP2D6, increased tadalafil 20-mg single-dose exposure (AUC) by 32% with a 30% reduction in C max , relative to the values for tadalafil 20 mg alone. Ritonavir (200 mg twice daily), increased tadalafil 20-mg single-dose exposure (AUC) by 124% with no change in Cmax , relative to the values for tadalafil 20 mg alone. Although specific interactions have not been studied, other HIV protease inhibitors would likely increase tadalafil exposure [see Dosage and Administration ( 2.7 )] . Cytochrome P450 Inducers — Studies have shown that drugs that induce CYP3A4 can decrease tadalafil exposure. CYP3A4 (e.g., Rifampin) — Rifampin (600 mg daily), a CYP3A4 inducer, reduced tadalafil 10-mg single-dose exposure (AUC) by 88% and Cmax by 46%, relative to the values for tadalafil 10 mg alone. Although specific interactions have not been studied, other CYP3A4 inducers, such as carbamazepine, phenytoin, and phenobarbital, would likely decrease tadalafil exposure. No dose adjustment is warranted. The reduced exposure of tadalafil with the coadministration of rifampin or other CYP3A4 inducers can be anticipated to decrease the efficacy of tadalafil for once daily use; the magnitude of decreased efficacy is unknown. 7.3 Potential for Tadalafil to Affect Other Drugs Aspirin — Tadalafil did not potentiate the increase in bleeding time caused by aspirin. Cytochrome P450 Substrates — Tadalafil is not expected to cause clinically significant inhibition or induction of the clearance of drugs metabolized by cytochrome P450 (CYP) isoforms. Studies have shown that tadalafil does not inhibit or induce P450 isoforms CYP1A2, CYP3A4, CYP2C9, CYP2C19, CYP2D6, and CYP2E1. CYP1A2 (e.g. Theophylline) — Tadalafil had no significant effect on the pharmacokinetics of theophylline. When tadalafil was administered to subjects taking theophylline, a small augmentation (3 beats per minute) of the increase in heart rate associated with theophylline was observed. CYP2C9 (e.g. Warfarin) — Tadalafil had no significant effect on exposure (AUC) to S-warfarin or R-warfarin, nor did tadalafil affect changes in prothrombin time induced by warfarin. CYP3A4 (e.g. Midazolam or Lovastatin) — Tadalafil had no significant effect on exposure (AUC) to midazolam or lovastatin. P-glycoprotein (e.g. Digoxin ) — Coadministration of tadalafil (40 mg once per day) for 10 days did not have a significant effect on the steady-state pharmacokinetics of digoxin (0.25 mg/day) in healthy subjects.

Tadalafil tablets are indicated for: - "Erectile dysfunction (ED)" - "The signs and symptoms of benign prostatic hyperplasia (BPH)" - "ED and the signs and symptoms of BPH (ED/BPH)" When used with finasteride for BPH, treatment for up to 26 weeks has been studied.

2 DOSAGE AND ADMINISTRATION Do not split Tadalafil tablets; entire dose should be taken. Tadalafil tablets for use as needed: ED: Starting dose: 10 mg as needed prior to sexual activity. Increase to 20 mg or decrease to 5 mg based upon efficacy/tolerability. Improves erectile function compared to placebo up to 36 hours post dose. Not to be taken more than once per day ( 2.1 ). Tadalafil tablets for once daily use: ED: 2.5 mg taken once daily, without regard to timing of sexual activity. May increase to 5 mg based upon efficacy and tolerability ( 2.2 ). BPH: 5 mg, taken at approximately the same time every day ( 2.3 ) ED and BPH: 5 mg, taken at approximately the same time every day ( 2.3 , 2.4 ) Tadalafil tablets may be taken without regard to food ( 2.5 ). 2.1 Tadalafil Tablets for Use as Needed for Erectile Dysfunction The recommended starting dose of tadalafil tablets for use as needed in most patients is 10 mg, taken prior to anticipated sexual activity. The dose may be increased to 20 mg or decreased to 5 mg, based on individual efficacy and tolerability. The maximum recommended dosing frequency is once per day in most patients. Tadalafil tablets for use as needed were shown to improve erectile function compared to placebo up to 36 hours following dosing. Therefore, when advising patients on optimal use of tadalafil tablets, this should be taken into consideration. 2.2 Tadalafil tablets for Once Daily Use for Erectile Dysfunction The recommended starting dose of tadalafil tablets for once daily use is 2.5 mg, taken at approximately the same time every day, without regard to timing of sexual activity. The tadalafil tablets dose for once daily use may be increased to 5 mg, based on individual efficacy and tolerability. 2.3 Tadalafil Tablets for Once Daily Use for Benign Prostatic Hyperplasia The recommended dose of tadalafil tablets for once daily use is 5 mg, taken at approximately the same time every day. When therapy for BPH is initiated with tadalafil and finasteride, the recommended dose of tadalafil tablets for once daily use is 5 mg, taken at approximately the same time every day for up to 26 weeks. 2.4 Tadalafil Tablets for Once Daily Use for Erectile Dysfunction and Benign Prostatic Hyperplasia The recommended dose of tadalafil tablets for once daily use is 5 mg, taken at approximately the same time every day, without regard to timing of sexual activity. 2.5 Use with Food Tadalafil tablets may be taken without regard to food. 2.6 Use in Specific Populations Renal Impairment Tadalafil tablets for Use as Needed Creatinine clearance 30 mL/min to 50 mL/min: A starting dose of 5 mg not more than once per day is recommended, and the maximum dose is 10 mg not more than once in every 48 hours. Creatinine clearance less than 30 mL/min or on hemodialysis: The maximum dose is 5 mg not more than once in every 72 hours [see Warnings and Precautions ( 5.7 ) and Use in Specific Populations ( 8.7 )] . Tadalafil tablets for Once Daily Use Erectile Dysfunction Creatinine clearance less than 30 mL/min or on hemodialysis: Tadalafil tablets for once daily use is not recommended [see Warnings and Precautions ( 5.7 ) and Use in Specific Populations ( 8.7 )] . Benign Prostatic Hyperplasia and Erectile Dysfunction/Benign Prostatic Hyperplasia Creatinine clearance 30 mL/min to 50 mL/min: A starting dose of 2.5 mg is recommended. An increase to 5 mg may be considered based on individual response. Creatinine clearance less than 30 mL/min or on hemodialysis: Tadalafil tablets for once daily use is not recommended [see Warnings and Precautions ( 5.7 ) and Use in Specific Populations ( 8.7 )] . Hepatic Impairment Tadalafil tablets for Use as Needed Mild or moderate (Child Pugh Class A or B): The dose should not exceed 10 mg once per day. The use of tadalafil tablets once per day have not been extensively evaluated in patients with hepatic impairment and therefore, caution is advised. Severe (Child Pugh Class C): The use of tadalafil tablets are not recommended [see Warnings and Precautions ( 5.8 ) and Use in Specific Populations ( 8.6 )] . Tadalafil tablets for Once Daily Use Mild or moderate (Child Pugh Class A or B): Tadalafil tablets for once daily use has not been extensively evaluated in patients with hepatic impairment. Therefore, caution is advised if tadalafil tablets for once daily use is prescribed to these patients. Severe (Child Pugh Class C): The use of tadalafil tablets are not recommended [see Warnings and Precautions ( 5.8 ) and Use in Specific Populations ( 8.6 )] . 2.7 Concomitant Medications Nitrates Concomitant use of nitrates in any form is contraindicated [see Contraindications ( 4.1 )] . Alpha-Blockers ED — When tadalafil tablets are coadministered with an alpha-blocker in patients being treated for ED, patients should be stable on alpha-blocker therapy prior to initiating treatment, and tadalafil tablets should be initiated at the lowest recommended dose [see Warnings and Precautions ( 5.6 ), Drug Interactions ( 7.1 ), and Clinical Pharmacology ( 12.2 )] . BPH — Tadalafil tablets are not recommended for use in combination with alpha-blockers for the treatment of BPH [ see Warnings and Precautions ( 5.6 ), Drug Interactions ( 7.1 ), and Clinical Pharmacology ( 12.2 )] . CYP3A4 Inhibitors Tadalafil tablets for Use as Needed — For patients taking concomitant potent inhibitors of CYP3A4, such as ketoconazole or ritonavir, the maximum recommended dose of tadalafil tablets is 10 mg, not to exceed once every 72 hours [see Warnings and Precautions ( 5.10 ) and Drug Interactions ( 7.2 )] . Tadalafil tablets for Once Daily Use — For patients taking concomitant potent inhibitors of CYP3A4, such as ketoconazole or ritonavir, the maximum recommended dose is 2.5 mg [see Warnings and Precautions ( 5.10 ) and Drug Interactions ( 7.2 )] .

Most common adverse reactions (≥2%) are "headache, dyspepsia, back pain, myalgia, nasal congestion, flushing, and pain in limb," with back pain and myalgia typically resolving within 48 hours of dosing. Less common effects include dizziness and dyspepsia with chronic dosing in BPH trials.