Generic name: Tadarich 2.5mg
Dosage form: tablet, film coated
The information at Drugs.com is not a substitute for medical advice. Always consult your doctor or pharmacist.
Do not split Tadarich tablets; entire dose should be taken.
The recommended dose of Tadarich for once daily use is 5 mg, taken at approximately the same time every day, without regard to timing of sexual activity.
Tadarich may be taken without regard to food.
Tadarich for Use as Needed
Tadarich for Once Daily Use
Benign Prostatic Hyperplasia and Erectile Dysfunction/Benign Prostatic Hyperplasia
Tadarich for Use as Needed
Tadarich for Once Daily Use
Concomitant use of nitrates in any form is contraindicated.
ED — When Tadarich is coadministered with an alpha-blocker in patients being treated for ED, patients should be stable on alpha-blocker therapy prior to initiating treatment, and Tadarich should be initiated at the lowest recommended dose.
BPH — Tadarich is not recommended for use in combination with alpha-blockers for the treatment of BPH.
Tadarich for Use as Needed — For patients taking concomitant potent inhibitors of CYP3A4, such as ketoconazole or ritonavir, the maximum recommended dose of Tadarich is 10 mg, not to exceed once every 72 hours.
Tadarich 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.
Tell your doctor about all medicines you use, and those you start or stop using during your treatment with Tadarich, especially:
St. John's wort;
an antibiotic--clarithromycin, erythromycin, telithromycin;
antifungal medication--itraconazole, ketoconazole, posaconazole, voriconazole;
heart or blood pressure medication--amlodipine nicardipine, quinidine;
hepatitis C medications--boceprevir, telaprevir;
HIV/AIDS medication--atazanavir, delavirdine, efavirenz, fosamprenavir, indinavir, nelfinavir, nevirapine, ritonavir, saquinavir;
seizure medication--carbamazepine, fosphenytoin, oxcarbazepine, phenobarbital, phenytoin, primidone; or
tuberculosis medication--isoniazid, rifabutin, rifampin, rifapentine.
This list is not complete. Other drugs may interact with Tadarich, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
5 mg Film-coated Tablet: Interaction studies were conducted with Tadarich 10 mg and/or 20 mg, as indicated as follows. With regard to those interaction studies where only the Tadarich 10 mg dose was used, clinically relevant interactions at higher doses cannot be completely ruled out. Effects of Other Substances on Tadarich:
Effects of Other Substances on Tadarich:Cytochrome P450 Inhibitors: Tadarich is principally metabolized by CYP3A4. A selective inhibitor of CYP3A4, ketoconazole (200 mg daily), increased Tadarich (10 mg) AUC 2-fold and Cmax by 15%, relative to the AUC and Cmax values for Tadarich alone. Ketoconazole (400 mg daily) increased Tadarich (20 mg) AUC 4-fold and Cmax by 22%. Ritonavir, a protease inhibitor (200 mg twice daily), which is an inhibitor of CYP3A4, CYP2C9, CYP2C19, and CYP2D6, increased Tadarich (20 mg) AUC 2-fold with no change in Cmax. Although specific interactions have not been studied, other protease inhibitors such as saquinavir and other CYP3A4 inhibitors eg, erythromycin, clarithromycin, itraconazole and grapefruit juice should be co-administered with caution as they would be expected to increase plasma concentrations of Tadarich.
Consequently the incidence of the adverse reactions might be increased..
Transporters: The role of transporters (for example p-glycoprotein) in the disposition of Tadarich is not known. Therefore, there is the potential of drug interactions mediated by inhibition of transporters.
Cytochrome P450 Inducers: A CYP3A4 inducer, rifampicin, reduced Tadarich AUC by 88%, relative to the AUC values for Tadarich alone (10 mg). This reduced exposure can be anticipated to decrease the efficacy of Tadarich; the magnitude of decreased efficacy is unknown. Other inducers of CYP3A4 such as phenobarbital, phenytoin and carbamazepine, may also decrease plasma concentrations of Tadarich.
Effects of Tadarich on Other Medicinal Products: Nitrates: In clinical studies, Tadarich (5, 10 and 20 mg) was shown to augment the hypotensive effects of nitrates. Therefore, administration of Tadarich to patientswho are using any form of organic nitrate is contraindicated.
Based on the results of a clinical study in which 150 subjects receiving daily doses of Tadarich 20 mg for 7 days and 0.4 mg sublingual nitroglycerin at various times, this interaction lasted for more than 24 hours and was no longer detectable when 48 hours had elapsed after the last Tadarich dose. Thus, in a patient prescribed any dose of Tadarich (2.5 mg-20 mg), where nitrate administration is deemed medically necessary in a life-threatening situation, at least 48 hours should have elapsed after the last dose of Tadarich before nitrate administration is considered. In such circumstances, nitrates should only be administered under close medical supervision with appropriate haemodynamic monitoring.
Antihypertensives (Including Calcium-Channel Blockers): The co-administration of doxazosin (4 and 8 mg daily) and Tadarich (5 mg daily dose and 20 mg as a single dose) increases the blood pressure-lowering effect of this alpha-blocker in a significant manner. This effect lasts at least twelve hours and may be symptomatic, including syncope. Therefore, this combination is not recommended.
In interaction studies performed in a limited number of healthy volunteers, these effects were not reported with alfuzosin or tamsulosin. However, caution should be exercised when using Tadarich in patients treated with any alpha-blockers, and notably in the elderly. Treatments should be initiated at minimal dosage and progressively adjusted.
In clinical pharmacology studies, the potential for Tadarich to augment the hypotensive effects of antihypertensive agents was examined. Major classes of antihypertensive agents were studied, including calcium channel blockers (amlodipine), angiotensin converting enzyme (ACE) inhibitors (enalapril), beta-adrenergic receptor blockers (metoprolol), thiazide diuretics (bendrofluazide), and angiotensin II receptor blockers (various types and doses, alone or in combination with thiazides, calcium channel blockers, beta-blockers, and/or alpha-blockers). Tadarich (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. In another clinical pharmacology study Tadarich (20 mg) was studied in combination with up to 4 classes of antihypertensives. In subjects taking multiple antihypertensives, the ambulatory-blood-pressure changes appeared to relate to the degree of blood-pressure control. In this regard, study subjects whose blood pressure was well controlled, the reduction was minimal and similar to that seen in healthy subjects. In study subjects whose blood pressure was not controlled, the reduction was greater although this reduction was not associated with hypotensive symptoms in the majority of subjects. In patients receiving concomitant antihypertensive medications, Tadarich 20 mg may induce a blood pressure decrease, which (with the exception of α-blockers previously mentioned) is, in general, minor and not likely to be clinically relevant. Analysis of phase 3 clinical trial data showed no difference in adverse events in patients taking Tadarich with or without antihypertensive medications. However, appropriate clinical advice should be given to patients regarding a possible decrease in blood pressure when they are treated with antihypertensive medications.
5-Alpha Reductase Inhibitors: In a clinical trial that compared Tadarich 5 mg co-administered with finasteride 5 mg to placebo plus finasteride 5 mg in the relief of BPH symptoms, no new adverse reactions were identified. However, as a formal drug-drug interaction study evaluating the effects of Tadarich and 5-alpha reductase inhibitors (5-ARIs) has not been performed, caution should be exercised when Tadarich is co-administered with 5-ARIs.
CYP1A2 Substrates (e.g. Theophylline): When Tadarich 10 mg was administered with theophylline (a non-selective phosphodiesterase inhibitor) in a clinical pharmacology study, there was no pharmacokinetic interaction. The only pharmacodynamic effect was a small (3.5 bpm) increase in heart rate. Although this effect is minor and was of no clinical significance in this study, it should be considered when co-administering these medications.
Ethinylestradiol and Terbutaline: Tadarich has been demonstrated to produce an increase in the oral bioavailability of ethinylestradiol; a similar increase may be expected with oral administration of terbutaline, although the clinical consequence of this is uncertain.
Alcohol: Alcohol concentrations (mean maximum blood concentration 0.08%) were not affected by co-administration with Tadarich (10 or 20 mg). In addition, no changes in Tadarich concentrations were seen 3 hours after co-administration with alcohol. Alcohol was administered in a manner to maximize the rate of alcohol absorption (overnight fast with no food until 2 hrs after alcohol). Tadarich (20 mg) did not augment the mean blood pressure decrease produced by alcohol [0.7 g/kg or approximately 180 mL of 40% alcohol (vodka) in an 80-kg male] but in some subjects, postural dizziness and orthostatic hypotension were observed. When Tadarich was administered with lower doses of alcohol (0.6 g/kg), hypotension was not observed and dizziness occurred with similar frequency to alcohol alone. The effect of alcohol on cognitive function was not augmented by Tadarich (10 mg).
Cytochrome P450 Metabolized Drugs: Tadarich is not expected to cause clinically significant inhibition or induction of the clearance of drugs metabolized by CYP450 isoforms. Studies have confirmed that Tadarich does not inhibit or induce CYP450 isoforms, including CYP3A4, CYP1A2, CYP2D6, CYP2E1, CYP2C9 and CYP2C19.
CYP2C9 Substrates (e.g. R-warfarin): Tadarich (10 and 20 mg) had no clinically significant effect on exposure (AUC) to S-warfarin or R-warfarin (CYP2C9 substrate), nor did Tadarich affect changes in prothrombin time induced by warfarin.
Aspirin: Tadarich (10 and 20 mg) did not potentiate the increase in bleeding time caused by acetylsalicylic acid.
Antidiabetic Medicinal Products: Specific interaction studies with antidiabetic medicinal products were not conducted.
20 mg: Potential for Other Drugs to Affect Tadarich: Tadarich is principally metabolised by CYP3A4. A selective inhibitor of CYP3A4, ketoconazole (400 mg daily), increased Tadarich single-dose exposure (AUC) by 312% and Cmax by 22%, and ketaconazole (200 mg daily), increased Tadarich single-dose exposure (AUC) by 107% and Cmax by 15% relative to the AUC and Cmax values for Tadarich (10 mg) alone. Ritonavir (200 mg twice daily), an inhibitor of CYP3A4, 2C9, 2C19, and 2D6, increased tadalafi single-dose exposure (AUC) by 124% with no change in Cmax. Although specific interactions have not been studied, other HIV protease inhibitors, such as saquinavir, and other CYP3A4 inhibitors, such as erythromycin, clarithromycin, and itraconazole should be co-administered with caution because they would be expected to increase plasma concentrations of Tadarich.A selective CYP3A4 inducer, rifampicin (600 mg daily), reduced Tadarich single-dose exposure(AUC) by 88%, and Cmax by 46% relative to the AUC and Cmax values for Tadarich (10 mg) alone. It can be expected that concomitant administration of other CYP3A4 inducers such as phenobarbital, phenytoin and carbamazepine would also decrease plasma concentrations of Tadarich.Studies with the CYP3A4 probe substrates midazolam with Tadarich 10 mg and lovastatin with Tadarich 20 mg showed little alteration in the kinetics suggesting that Tadarich is unlikely to have interactions with CYP3A4 substrates. Antacids (Magnesium hydroxide/Aluminium hydroxide): H2 Antagonists:
Antacids (Magnesium hydroxide/Aluminium hydroxide):Simultaneous administration of an antacid(magnesium hydroxide/aluminium hydroxide) and Tadarich reduced the apparent rate of absorption of Tadarich without altering exposure (AUC) to Tadarich (10 mg).
H2 Antagonists:An increase in gastric pH resulting from administration of nizatidine had no significant effect on Tadarich (10 mg) pharmacokinetics.
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Information checked by Dr. Sachin Kumar, MD Pharmacology