Rifabutin Isoniazid

HIV - The initial phase of a 6-month tuberculosis regimen consists of isoniazid, rifabutin, pyrazinamide, and ethambutol for patients receiving therapy with protease inhibitors or nonnucleoside reverse transcriptase inhibitors. These drugs are administered a) daily for at least the first 2 weeks, followed by twice weekly dosing for 6 weeks or b) daily for 8 weeks to complete the 2-month induction phase. The second phase of treatment consists of rifabutin and isoniazid administered twice weekly or daily for 4 months. 

A 35-year old Caucasian man with AIDS and multiple opportunistic infections, including Mycobacterium kansasii and Mycobacterium avium complex (MAC) disease developed moderate to severe primary sensorineural hearing loss after 4—5 months of therapy with oral azithromycin 500 mg/day. Other medications included ethambutol, isoniazid, rifabutin, ciprofloxacin, co-trimoxazole, fluconazole, zidovudine (later switched to stavudine), lamivudine, indinavir, methadone, mod-ified-release oral morphine, pseudoephedrine, diphenhydramine, megestrol acetate, trazodone, sorbitol, salbutamol by metered-dose inhaler and nebulizer, ipratropium, and oral morphine solution as needed. Significant improvement of the hearing impairment was documented 3 weeks after drug withdrawal. 

A) Amikacin, isoniazid, pyrazinamide, streptomycin Ciprofloxacin, cycloserine, isoniazid, PAS Ethambutol, isoniazid, rifabutin, streptomycin Ethambutol, pyrazinamide, rifampin, streptomycin Isoniazid, rifampin, pyrazinamide, ethambutol... 

Rifampicin, the only commercially available ansamacroHde, is manufactured by MerreU Dow under the tradename Rifadin, and by CIBA under the trade name Rimactane. Rifampicin is also suppHed in combination with isoniazid or pyrazinamide [98-96-4]. The rifampicin—isoniazid combination is known as Rifamate (MerreU Dow), Rifinah (MerreU Dow), and Rimactazid (CIBA) the rifampicin—pyrazinamide as Rifater (MerreU Dow). Several other rifamycin derivatives including rifabutin and rifapentine are undergoing clinical studies. 

P-lactam antimicrobials, gatifloxacin, indinavir, isoniazid, levofloxacin, nitrofurantoin, ribavirin, rifabutin, rifampin, silver sulfadiazine, streptomycin, sulfonamide antimicrobials, and tetracyclines... 

Rifampin Daily for 4 months For persons who are contacts of patients with isoniazid-resistant rifampin susceptible TB. In HIV-infected patients, protease inhibitors or NNRTIs generally should not be administered concurrently with rifampin rifabutin can be used as an alternative for patients treated with indinavir, nelfinavir, amprenivir, ritonavir, orefavirenz, and possibly with nevirapine or soft-gel saquinavir5 B (II) B (III)... 

There is no evidence that rifabutin is effective prophylaxis against M. tuberculosis. Patients requiring prophylaxis against both M. tuberculosis and M. avium complex may be given isoniazid and rifabutin concurrently. 

Isoniazid Avasimibe Bosentan Carbam- a2epine" Clotrimazole Cyproterone acetate Hyperforin Lovastatin Mifepristone Nelfinavir Nifedipine Omeprazole Paclitaxel Phenobarbital Phenytoin Rifabutin Rifampin"" Rifapentine Ritonavir Simvastatin Sulfinpyrazole Topotecan Troglitazone Troleandomycin Vitamin E Vitamin K2 Yin zhi wuang... 

The drugs used to treat TB include capreomycin, cycloserine, ethambutol, isoniazid, pyrazinamide, rifabutin, rifampicin and streptomycin. Resistance is most likely with long courses of treatment of antimicrobial agents and treatment courses are six (or even nine) months long. 

Isoniazid 900 mg orally plus pyridoxine 100 rrrg orally twice weekly for 9 months (Bll) Rifampin 600 mg orally once daily (AIIO or rifabutin 300 mg orally once daily (Bill) for 4 months... 

Unfortunately, MAC is resistant to the standard drugs used for tuberculosis, such as isoniazid and pyrazinamide. Multiple agents such as rifampin, rifabutin (ansamycin), clofazimine, imipenem, amikacin, ethambutol, ciprofloxacin, clarithromycin, and azithromycin have varying degrees of in vitro anti-MAC activity. Controversy formerly existed as to whether treatment for MAC is beneficial, but data indicate that an aggressive therapeutic approach decreases symptoms... 

MAC is much less susceptible than M tuberculosis to conventional antimycobacterial drugs. Both isoniazid and pyrazinamide have minimal activity against MAC. Currently, the optimum regimen consists of clarithromycin for azithromycin) with ethambutol and rifabutin. The answer is (D). 

Because of indinavir s metabolism, a number of drug interactions are possible. Indinavir interacts with rifabutin or ketoconazole, leading to increased or decreased indinavir concentration, respectively, in the blood plasma. Administration of drug combinations of indinavir with antiviral nucleoside analogues, cimetidine, quinidine, trimethoprim/sulfamethoxazole, fluconazole, or isoniazid resulted in an increased activity of indinavir. Indinavir is ... 

Antimycobacterials and related drugs Aminosalicylic acid (PAS), Capreomycin, Clofazimine, Cycloserine, Dapsone, Ethambutol, Ethionamide, Isoniazid, Methaniazide, Protionamide, Pyrazinamide, Rifabutin, Rifampicin (Rifampin), Rifamycin, Rihipentine, Rihiximin... 

The concurrent use of a lifamycin and isoniazid is common and therapeutically valuable, but there is evidence that the incidence of hepatotoxicity may be increased, particularly in slow acetylators of isoniazid. One study su ests the bioavailability of rifampicin may be reduced by isoniazid but other studies found no pharmacokinetic interaction. Rifabutin and rifampicin do not alter the pharmacokinetics of isoniazid. 

Rifabutin 300 mg, given daily for 7 days to 6 healthy subjeets, had no significant effect on the pharmacokinetics of a single 300-mg dose of isoniazid or its metabolite acetylisoniazid. Two of the 6 subjects were rapid acetylators of isoniazid (see Genetic factors , (p.4), for more information about acetylator status). 

The CDC in the US state that the combination is probably clinically useful, and they suggest increasing the dose of rifabutin to 450 mg or 600 mg daily, or 600 mg two to three times weekly. In one study doubling the rifabutin dose from 300 mg twice weekly to 600 mg twice weekly when starting efavirenz resulted in rifabutin AUCs that were 20% higher than baseline values. However, in one analysis, 8 of 35 patients (23%) taking efavirenz and given rifabutin 450 mg once daily were found to have sub-therapeutic rifabutin levels, and they were switched to isoniazid. Concurrent use should therefore be closely monitored. 

Ciclosporin serum levels are markedly reduced by rifampicin and transplant rejection can rapidly develop. Rifamycin seems to interact similarly, but limited evidence suggests that rifabutin interacts to a lesser extent. Ethambutol and isoniazid do not generally appear to interact with ciclosporin although case reports have described alterations in ciclosporin levels. 

The clearance of ciclosporin in a patient with a kidney transplant doubled when isoniazid, ethambutol, pyridoxine and rifampicin 600 mg daily were given. When these drugs were replaced by rifabutin 150 mg and clofazimine 100 mg daily the ciclosporin clearance fell to about its former levels, but after about 3 weeks the clearance was about 20% greater than before the antimycobacterial drugs were given. ... 

Rifampicin (rifampin) lowers the serum levels of theophylline, but rifabutin appears to have little effect. Isoniazid may decrease or increase theophylline clearance and may increase theophylline levels. An isolated report describes theophylline toxicity one month after a patient started to take theophyUine with isoniazid. Isoniazid and rifampicin increased theophylline clearance during the initial few days of tuberculosis treatment in one study, but there is some evidence that it decreases it within 4 weeks in another. 

Rifampicin is a potent liver enzyme inducer, which increases the metabolism of the theophylline, thereby increasing its clearance and reducing its serum levels. It has been suggested that isoniazid inhibits the metabolism of theophylline by the liver, thereby reducing its clearance and increasing its plasma levels. Rifabutin is a much less potent liver enzyme inducer than rifampicin, and consequently has less of an effect on theophylline metabolism. 

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