PRIFTIN is indicated for the treatment of pulmonary tuberculosis.
PRIFTIN must always be used in conjunction with at least one other antituberculosis drug to which the isolate is susceptible.
In the intensive phase of the short-course treatment of pulmonary tuberculosis, PRIFTIN should be administered twice weekly for two months, with an interval of no less than 3 days (72 hours) between doses, as part of an appropriate regimen which includes daily companion drugs (Table 2-1).
It may also be necessary to add either streptomycin or ethambutol until the results of susceptibility testing are known.
Compliance with all drugs in the Intensive Phase (ie, PRIFTIN, isoniazid, pyrazinamide, ethambutol or streptomycin) is imperative to assure early sputum conversion and protection against relapse.
Following the intensive phase, Continuation Phase treatment should be continued with PRIFTIN for 4 months.
During this phase, PRIFTIN should be administered on a once-weekly basis in combination with an appropriate antituberculous agent for susceptible organisms (Table 2-1) (see DOSAGE AND ADMINISTRATION section).In the treatment of tuberculosis, the small number of resistant cells present within large populations of susceptible cells can rapidly become the predominant type.
Consequently, clinical samples for mycobacterial culture and susceptibility testing should be obtained prior to the initiation of therapy, as well as during treatment to monitor therapeutic response.
The susceptibility of M.
tuberculosis organisms to isoniazid, rifampin, pyrazinamide, ethambutol, rifapentine and other appropriate agents should be measured.If test results show resistance to any of these drugs and the patient is not responding to therapy, the drug regimen should be modified.
Poor compliance with the dosage regimen, particularly the daily administered non-rifamycin drugs in the Intensive Phase, was associated with late sputum conversion and a high relapse rate in the rifapentine arm of Clinical Study 008.
Therefore, compliance with the full course of therapy must be emphasized, and the importance of not missing any doses must be stressed.
(See PRECAUTIONS and DOSAGE AND ADMINISTRATION.)Since antituberculous multidrug treatments, including the rifamycin class, are associated with serious hepatic events, patients with abnormal liver tests and/or liver disease should only be given rifapentine in cases of necessity and then with caution and under strict medical supervision.
In these patients, careful monitoring of liver tests (especially serum transaminases) should be carried out prior to therapy and then every 2 to 4 weeks during therapy.
If signs of liver disease occur or worsen, rifapentine should be discontinued.
Hepatotoxicity of other antituberculosis drugs (eg, isoniazid, pyrazinamide) used in combination with rifapentine should also be taken into account.Hyperbilirubinemia resulting from competition for excretory pathways between rifapentine and bilirubin cannot be excluded since competition between the related drug rifampin and bilirubin can occur.
An isolated report showing a moderate rise in bilirubin and/or transaminase level is not in itself an indication for interrupting treatment; rather, the decision should be made after repeating the tests, noting trends in the levels and considering them in conjunction with the patient's clinical condition.
Pseudomembranous colitis has been reported to occur with various antibiotics, including other rifamycins.
Diarrhea, particularly if severe and/or persistent, occurring during treatment or in the initial weeks following treatment may be symptomatic of Clostridium difficile-associated disease, the most severe form of which is pseudomembranous colitis.
If pseudomembranous colitis is suspected, rifapentine should be stopped immediately and the patient should be treated with supportive and specific treatment without delay (eg, oral vancomycin).
Products inhibiting peristalsis are contraindicated in this clinical situation.
Experience in HIV-infected patients is limited.
In an ongoing CDC TB trial, five out of 30 HIV?infected patients randomized to once weekly rifapentine (plus INH) in the Continuation Phase who completed treatment, relapsed.
Four of these patients developed rifampin mono-resistant (RMR) TB.
Each RMR patient had late-stage HIV infection, low CD4 counts and extrapulmonary disease, and documented co-administration of antifungal azoles (See Reference 1).
These findings are consistent with the literature in which an emergence of RMR TB in HIV-infected TB patients has been reported in recent years.
Further study in this sub-population is warranted.
As with other antituberculous treatments, when rifapentine is used in HIV?infected patients, a more aggressive regimen should be employed (eg, more frequent dosing).Based on results to date of the CDC trial (see above), once weekly dosing during the Continuation Phase of treatment is not recommended at this time.Because rifapentine has been shown to increase indinavir metabolism (see DRUG INTERACTIONS), it should be used with extreme caution, if at all, in patients who are also taking protease inhibitors.