Tadalafil Side Effects, Interactions, and Warnings
Tadalafil is part of a drug class of Selective cGMP Phosphodiesterase Type 5 Inhibitors. It’s created by NORTHSTAR RX. Like most medicines, side effects can happen when taking Tadalafil.
Side effects of Tadalafil
| a The term flushing includes: facial flushing and flushing | ||||
| Adverse Reaction | Placebo (N=476) | Tadalafil 5 mg (N=151) | Tadalafil 10 mg (N=394) | Tadalafil 20 mg (N=635) |
| Headache | 5% | 11% | 11% | 15% |
| Dyspepsia | 1% | 4% | 8% | 10% |
| Back pain | 3% | 3% | 5% | 6% |
| Myalgia | 1% | 1% | 4% | 3% |
| Nasal congestion | 1% | 2% | 3% | 3% |
| Flushing a | 1% | 2% | 3% | 3% |
| Pain in limb | 1% | 1% | 3% | 3% |
Some Tadalafil side effects do not require medical attention. Commonly reported side effects often improve as your body adjusts to the medication. However, in the event of persistent or worsening Tadalafil side effects, it’s best to contact your healthcare professional.
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Adverse reactions
When to contact a doctor about Tadalafil side effects
Contact a physician if you experience any of the severe Tadalafil side effects listed above. Some of these adverse effects may require immediate medical attention.
Signs of a Tadalafil allergy:
- Skin rash
- Trouble breathing
- Swelling of the lips, face, or throat
- Wheezing
- Runny nose
- Watery, itchy eyes
Anaphylaxis is a rare but life-threatening allergic reaction. Signs of anaphylaxis include:
- Closing of the airways and throat
- Nausea
- Abdominal pain
- Vomiting
- Diarrhea
- Dizziness or lightheadedness
- Rapid or weak pulse
- Reduced blood pressure
- Seizures
- Loss of consciousness
Other 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. H 2 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 C max 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 C max 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 C max , 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 C max 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 contraindications
Administration of tadalafil tablets to patients using any form of organic nitrate is contraindicated. Tadalafil tablets were shown to potentiate the hypotensive effect of nitrates ( 4.1 ). History of known serious hypersensitivity reaction to tadalafil tablets or ADCIRCA ® ( 4.2 ). Administration with guanylate cyclase (GC) stimulators, such as riociguat ( 4.3 ). 4.1 Nitrates Administration of tadalafil tablets to patients who are using any form of organic nitrate, either regularly and/or intermittently, is contraindicated. In clinical pharmacology studies, tadalafil tablets were shown to potentiate the hypotensive effect of nitrates [see Clinical Pharmacology (12.2) ] . 4.2 Hypersensitivity Reactions Tadalafil tablets are contraindicated in patients with a known serious hypersensitivity to tadalafil tablets or ADCIRCA ® . Hypersensitivity reactions have been reported, including Stevens-Johnson syndrome and exfoliative dermatitis [see Adverse Reactions (6.2) ] . 4.3 Concomitant Guanylate Cyclase (GC) Stimulators Do not use tadalafil tablets in patients who are using a GC stimulator, such as riociguat. PDE5 inhibitors, including tadalafil tablets, may potentiate the hypotensive effects of GC stimulators.
Tadalafil during pregnancy
Tadalafil is not indicated for use in females. There are no data with the use of tadalafil in pregnant women to inform any drug-associated risks for adverse developmental outcomes. In animal reproduction studies, no adverse developmental effects were observed with oral administration of tadalafil to pregnant rats or mice during organogenesis at exposures up to 11 times the maximum recommended human dose (MRHD) of 20 mg/day ( see Data). Data Animal Data Animal reproduction studies showed no evidence of teratogenicity, embryotoxicity, or fetotoxicity when tadalafil was given orally to pregnant rats or mice at exposures up to 11 times the maximum recommended human dose (MRHD) of 20 mg/day during organogenesis. In a prenatal/postnatal developmental study in rats, postnatal pup survival decreased following maternal exposure to tadalafil doses greater than 10 times the MRHD based on AUC. Signs of maternal toxicity occurred at doses greater than 16 times the MRHD based on AUC. Surviving offspring had normal development and reproductive performance. In another rat prenatal and postnatal development study at doses of 60, 200, and 1000 mg/kg, a reduction in postnatal survival of pups was observed. The no observed effect level (NOEL) for maternal toxicity was 200 mg/kg/day and for developmental toxicity was 30 mg/kg/day. This gives approximately 16 and 10 fold exposure multiples, respectively, of the human AUC for the MRHD of 20 mg. Tadalafil and/or its metabolites cross the placenta, resulting in fetal exposure in rats.
This may not be a complete list of all possible Tadalafil risks. Consult your healthcare professional for medical advice on avoiding side effects of Tadalafil and other contraindications, warnings, and interactions that may apply to you, your health conditions, and your list of medications. You can also report other adverse reactions of Tadalafil to the FDA at 1-800-FDA-1088.
Nursing mothers
8.3 Females and Males of Reproductive Potential Infertility Based on the data from 3 studies in adult males, tadalafil decreased sperm concentrations in the study of 10 mg tadalafil for 6 months and the study of 20 mg tadalafil for 9 months. This effect was not seen in the study of 20 mg tadalafil taken for 6 months. There was no adverse effect of tadalafil 10 mg or 20 mg on mean concentrations of testosterone, luteinizing hormone or follicle stimulating hormone. The clinical significance of the decreased sperm concentrations in the two studies is unknown. There have been no studies evaluating the effect of tadalafil on fertility in men [see Clinical Pharmacology (12.2) ] . Based on studies in animals, a decrease in spermatogenesis was observed in dogs, but not in rats [see Nonclinical Toxicology (13.1) ] .
Geriatric use
Of the total number of subjects in ED clinical studies of tadalafil, approximately 19 percent were 65 and over, while approximately 2 percent were 75 and over. Of the total number of subjects in BPH clinical studies of tadalafil (including the ED/BPH study), approximately 40 percent were over 65, while approximately 10 percent were 75 and over. In these clinical trials, no overall differences in efficacy or safety were observed between older (>65 and ≥75 years of age) and younger subjects (≤65 years of age). However, in placebo-controlled studies with tadalafil for use as needed for ED, diarrhea was reported more frequently in patients 65 years of age and older who were treated with tadalafil (2.5% of patients) [see Adverse Reactions (6.1) ] . No dose adjustment is warranted based on age alone. However, a greater sensitivity to medications in some older individuals should be considered. [see Clinical Pharmacology (12.3) ] .
Pediatric use
Tadalafil is not indicated for use in pediatric patients. Safety and efficacy in patients below the age of 18 years have not been established. A randomized, double-blind, placebo-controlled trial in pediatric patients (7 to 14 years of age) with Duchenne muscular dystrophy, who received tadalafil 0.3 mg/kg, tadalafil 0.6 mg/kg, or placebo daily for 48 weeks failed to demonstrate any benefit of treatment with tadalafil on a range of assessments of muscle strength and performance. Juvenile Animal Study No adverse effects were observed in a study in which tadalafil was administered orally at doses of 60, 200, and 1000 mg/kg/day to juvenile rats on postnatal days 14 to 90. The highest plasma tadalafil exposures (AUC) achieved were approximately 10-fold that observed at the MRHD.
Description
Tadalafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Tadalafil has the molecular formula C 22 H 19 N 3 O 4 representing a molecular weight of 389.41. The structural formula is: The chemical designation is pyrazino[1′,2′:1,6]pyrido[3,4-b]indole-1,4-dione, 6-(1,3-benzodioxol-5-yl)-2,3,6,7,12,12a-hexahydro-2-methyl-, (6R,12aR)-. It is a white or almost white powder that is practically insoluble in water and very slightly soluble in ethanol. Tadalafil tablets USP are available as oval shaped tablets for oral administration. Each tablet contains 2.5 mg, 5 mg, 10 mg, or 20 mg of tadalafil USP and the following inactive ingredients: colloidal silicon dioxide, copovidone, croscarmellose sodium, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyoxyl 40 hydrogenated castor oil, talc, titanium dioxide, triacetin, and yellow iron oxide. In addition the 2.5 mg also contains red iron oxide. Chemical Structure
Indications and usage
Tadalafil is a phosphodiesterase 5 (PDE5) inhibitor indicated for the treatment of: erectile dysfunction (ED) (1.1) the signs and symptoms of benign prostatic hyperplasia (BPH) (1.2) ED and the signs and symptoms of BPH (ED/BPH) (1.3) If tadalafil tablets are used with finasteride to initiate BPH treatment, such use is recommended for up to 26 weeks ( 1.4 ). 1.1 Erectile Dysfunction Tadalafil tablets are indicated for the treatment of erectile dysfunction (ED). 1.2 Benign Prostatic Hyperplasia Tadalafil tablets are indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH). 1.3 Erectile Dysfunction and Benign Prostatic Hyperplasia Tadalafil tablets are indicated for the treatment of ED and the signs and symptoms of BPH (ED/BPH). 1.4 Limitation of Use If tadalafil tablets are used with finasteride to initiate BPH treatment, such use is recommended for up to 26 weeks because the incremental benefit of tadalafil tablets decreases from 4 weeks until 26 weeks, and the incremental benefit of tadalafil tablets beyond 26 weeks is unknown [see Clinical Studies (14.3) ].
Use in specific populations
Hepatic Impairment (2.6, 5.8, 8.6) : Mild or Moderate: Dosage adjustment may be needed. Severe: Use is not recommended. Renal Impairment (2.6, 5.7, 8.7) : Patients with creatinine clearance 30 to 50 mL/min: Dosage adjustment may be needed. Patients with creatinine clearance less than 30 mL/min or on hemodialysis: For use as needed: Dose should not exceed 5 mg every 72 hours. Once daily use is not recommended. 8.1 Pregnancy Risk Summary Tadalafil is not indicated for use in females. There are no data with the use of tadalafil in pregnant women to inform any drug-associated risks for adverse developmental outcomes. In animal reproduction studies, no adverse developmental effects were observed with oral administration of tadalafil to pregnant rats or mice during organogenesis at exposures up to 11 times the maximum recommended human dose (MRHD) of 20 mg/day ( see Data). Data Animal Data Animal reproduction studies showed no evidence of teratogenicity, embryotoxicity, or fetotoxicity when tadalafil was given orally to pregnant rats or mice at exposures up to 11 times the maximum recommended human dose (MRHD) of 20 mg/day during organogenesis. In a prenatal/postnatal developmental study in rats, postnatal pup survival decreased following maternal exposure to tadalafil doses greater than 10 times the MRHD based on AUC. Signs of maternal toxicity occurred at doses greater than 16 times the MRHD based on AUC. Surviving offspring had normal development and reproductive performance. In another rat prenatal and postnatal development study at doses of 60, 200, and 1000 mg/kg, a reduction in postnatal survival of pups was observed. The no observed effect level (NOEL) for maternal toxicity was 200 mg/kg/day and for developmental toxicity was 30 mg/kg/day. This gives approximately 16 and 10 fold exposure multiples, respectively, of the human AUC for the MRHD of 20 mg. Tadalafil and/or its metabolites cross the placenta, resulting in fetal exposure in rats. 8.2 Lactation Risk Summary Tadalafil is not indicated for use in females. There is no information on the presence of tadalafil and/or metabolites in human milk, the effects on the breastfed child, or the effects on milk production. Tadalafil and/or its metabolites are present in the milk of lactating rats at concentrations approximately 2.4-fold greater than found in the plasma. 8.3 Females and Males of Reproductive Potential Infertility Based on the data from 3 studies in adult males, tadalafil decreased sperm concentrations in the study of 10 mg tadalafil for 6 months and the study of 20 mg tadalafil for 9 months. This effect was not seen in the study of 20 mg tadalafil taken for 6 months. There was no adverse effect of tadalafil 10 mg or 20 mg on mean concentrations of testosterone, luteinizing hormone or follicle stimulating hormone. The clinical significance of the decreased sperm concentrations in the two studies is unknown. There have been no studies evaluating the effect of tadalafil on fertility in men [see Clinical Pharmacology (12.2) ] . Based on studies in animals, a decrease in spermatogenesis was observed in dogs, but not in rats [see Nonclinical Toxicology (13.1) ] . 8.4 Pediatric Use Tadalafil is not indicated for use in pediatric patients. Safety and efficacy in patients below the age of 18 years have not been established. A randomized, double-blind, placebo-controlled trial in pediatric patients (7 to 14 years of age) with Duchenne muscular dystrophy, who received tadalafil 0.3 mg/kg, tadalafil 0.6 mg/kg, or placebo daily for 48 weeks failed to demonstrate any benefit of treatment with tadalafil on a range of assessments of muscle strength and performance. Juvenile Animal Study No adverse effects were observed in a study in which tadalafil was administered orally at doses of 60, 200, and 1000 mg/kg/day to juvenile rats on postnatal days 14 to 90. The highest plasma tadalafil exposures (AUC) achieved were approximately 10-fold that observed at the MRHD. 8.5 Geriatric Use Of the total number of subjects in ED clinical studies of tadalafil, approximately 19 percent were 65 and over, while approximately 2 percent were 75 and over. Of the total number of subjects in BPH clinical studies of tadalafil (including the ED/BPH study), approximately 40 percent were over 65, while approximately 10 percent were 75 and over. In these clinical trials, no overall differences in efficacy or safety were observed between older (>65 and ≥75 years of age) and younger subjects (≤65 years of age). However, in placebo-controlled studies with tadalafil for use as needed for ED, diarrhea was reported more frequently in patients 65 years of age and older who were treated with tadalafil (2.5% of patients) [see Adverse Reactions (6.1) ] . No dose adjustment is warranted based on age alone. However, a greater sensitivity to medications in some older individuals should be considered. [see Clinical Pharmacology (12.3) ] . 8.6 Hepatic Impairment In clinical pharmacology studies, tadalafil exposure (AUC) in subjects with mild or moderate hepatic impairment (Child-Pugh Class A or B) was comparable to exposure in healthy subjects when a dose of 10 mg was administered. There are no available data for doses higher than 10 mg of tadalafil in patients with hepatic impairment. Insufficient data are available for subjects with severe hepatic impairment (Child-Pugh Class C). [see Dosage and Administration (2.6) and Warnings and Precautions (5.8) ]. 8.7 Renal Impairment In clinical pharmacology studies using single-dose tadalafil (5 to 10 mg), tadalafil exposure (AUC) doubled in subjects with creatinine clearance 30 to 80 mL/min. In subjects with end-stage renal disease on hemodialysis, there was a two-fold increase in C max and 2.7- to 4.8-fold increase in AUC following single-dose administration of 10 or 20 mg tadalafil. Exposure to total methylcatechol (unconjugated plus glucuronide) was 2- to 4-fold higher in subjects with renal impairment, compared to those with normal renal function. Hemodialysis (performed between 24 and 30 hours post-dose) contributed negligibly to tadalafil or metabolite elimination. In a clinical pharmacology study (N=28) at a dose of 10 mg, back pain was reported as a limiting adverse event in male patients with creatinine clearance 30 to 50 mL/min. At a dose of 5 mg, the incidence and severity of back pain was not significantly different than in the general population. In patients on hemodialysis taking 10 or 20 mg tadalafil, there were no reported cases of back pain. [see Dosage and Administration (2.6) and Warnings and Precautions (5.7) ].
