Rifater

Generic Name: rifampin, isoniazid and pyrazinamide
Brand Name: Rifater
Drug Class: Antitubercular Agents

side effects drug center rifater (rifampin, isoniazid and pyrazinamide) drug

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PROFESSIONAL CONSUMER SIDE EFFECTS

Drug Description

What is Rifater and how is it used?

Rifater is (isoniazid, rifampicin and pyrazinamide) is a combination drug used to treat tuberculosis (BS).

What are side effects of Rifater?

Common side effects of Rifater include:

nausea,
vomiting,
upset stomach,
stomach pain,
heartburn,
diarrhea,
muscle or joint pain,
headache,
rash or itching,
drowsiness,
dizziness,
spinning sensation,
ringing in your ears, or
numbness or tingling in your legs.

WARNING

Severe and sometimes fatal hepatitis associated with isoniazid therapy may occur and may develop even after many months of treatment. The risk of developing hepatitis is age related. Approximate case rates by age are: 0 per 1,000 for persons under 20 years of age, 3 per 1,000 for persons in the 20 to 34 year age group, 12 per 1,000 for persons in the 35 to 49 year age group, 23 per 1,000 for persons in the 50 to 64 year age group, and 8 per 1,000 for persons over 65 years of age. The risk of hepatitis is increased with daily consumption of alcohol. Precise data to provide a fatality rate for isoniazid-related hepatitis is not available; however, in a U.S. Public Health Service Surveillance Study of 13,838 persons taking isoniazid, there were 8 deaths among 174 cases of hepatitis.

Therefore, patients given isoniazid should be carefully monitored and interviewed at monthly intervals. Serum transaminase concentration becomes elevated in about 10% to 20% of patients, usually during the first few months of therapy, but it can occur at any time. Usually enzyme levels return to normal despite continuance of drug, but in some cases progressive liver dysfunction occurs. Patients should be instructed to report immediately any of the prodromal symptoms of hepatitis, such as fatigue, weakness, malaise, anorexia, nausea, or vomiting. If these symptoms appear or if signs suggestive of hepatic damage are detected, isoniazid should be discontinued promptly since continued use of the drug in these cases has been reported to cause a more severe form of liver damage.

Patients with tuberculosis should be given appropriate treatment with alternative drugs. If isoniazid must be reinstituted, it should be reinstituted only after symptoms and laboratory abnormalities have cleared. The drug should be restarted in very small and gradually increasing doses and should be withdrawn immediately if there is any indication of recurrent liver involvement. Treatment should be deferred in persons with acute hepatic diseases.

DESCRIPTION

RIFATER (rifampin/isoniazid/pyrazinamide USP) tablets are combination tablets containing 120 mg rifampin, 50 mg isoniazid, and 300 mg pyrazinamide for use in antibacterial therapy. The tablets also contain as inactive ingredients: povidone, carboxymethyl cellulose sodium, calcium stearate, sodium lauryl sulfate, sucrose, talc, acacia, titanium dioxide, kaolin, magnesium carbonate, colloidal silicon dioxide, dried aluminum hydroxide gel, ferric oxide, black iron oxide, carnauba wax, white beeswax, colophony, hard paraffin, lecithin, shellac, and propylene glycol. The RIFATER triple therapy combination was developed for dosing convenience.

Rifampin

Rifampin is a semisynthetic antibiotic derivative of rifamycin SV. Rifampin is a red-brown crystalline powder very slightly soluble in water at neutral pH, freely soluble in chloroform, soluble in ethyl acetate and methanol. Its molecular weight is 822.95 and its chemical formula is C₄₃H₅₈N₄O₁₂. The chemical name for rifampin is either: 3-[[(4-methyl-1-piperazinyl)imino]methyl]-rifamycin or 5,6,9,17,19,21-hexahydroxy-23-methoxy-2,4,12,16,18,20,22– heptamethyl-8-[N-(4-methyl-1-piperazinyl) formimidoyl]-2,7-(epoxypentadeca [1,11,13]trienimino)naphtho[2,1-b]furan-1,11(2H)-dione 21-acetate. Its structural formula is:

Isoniazid

Isoniazid is the hydrazide of isonicotinic acid. It is a colorless or white crystalline powder or white crystals. It is odorless and slowly affected by exposure to air and light. It is freely soluble in water, sparingly soluble in alcohol and slightly soluble in chloroform and in ether. Its molecular weight is 137.14 and its chemical formula is C₆H₇N₃O.

The chemical name for isoniazid is 4-pyridinecarboxylic acid, hydrazide and its structural formula is:

Isoniazid - Structural Formula Illustration

Pyrazinamide

Pyrazinamide, the pyrazine analogue of nicotinamide, is a white, crystalline powder, stable at room temperature, and sparingly soluble in water. The chemical name for pyrazinamide is pyrazinecarboxamide and its molecular weight is 123.11. Its chemical formula is C₅H₅N₃O and its structural formula is:

Indications

INDICATIONS

RIFATER is indicated in the initial phase of the short-course treatment of pulmonary tuberculosis. During this phase, which should last 2 months, RIFATER should be administered on a daily, continuous basis (see DOSAGE AND ADMINISTRATION).

Following the initial phase and treatment with RIFATER, treatment should be continued with rifampin and isoniazid (e.g., RIFAMATE) for at least 4 months. Treatment should be continued for a longer period of time if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.

In the treatment of tuberculosis, the small number of resistant cells present within large populations of susceptible cells can rapidly become the predominant type. Since resistance can emerge rapidly, susceptibility tests should be performed in the event of persistent positive cultures during the course of treatment. Bacteriologic smears or cultures should be obtained before the start of therapy to confirm the susceptibility of the organism to rifampin, isoniazid, and pyrazinamide and they should be repeated throughout therapy to monitor response to the treatment. If test results show resistance to any of the components of RIFATER and the patient is not responding to therapy, the drug regimen should be modified.

Dosage

DOSAGE AND ADMINISTRATION

RIFATER is recommended in the initial phase of short-course therapy which is usually continued for 2 months. The Advisory Council for the Elimination of Tuberculosis, the American Thoracic Society, and the Centers for Disease Control and Prevention recommend that either streptomycin or ethambutol be added as a fourth drug in a regimen containing isoniazid (INH), rifampin, and pyrazinamide for initial treatment of tuberculosis unless the likelihood of INH or rifampin resistance is very low. The need for a fourth drug should be reassessed when the results of susceptibility testing are known. If community rates of INH resistance are currently less than 4%, an initial treatment regimen with less than four drugs may be considered.

Following the initial phase, treatment should be continued with rifampin and isoniazid (e.g., RIFAMATE®) for at least 4 months. Treatment should be continued for longer if the patient is still sputum or culture positive, if resistant organisms are present, or if the patient is HIV positive.

Concomitant administration of pyridoxine (B6) is recommended in the malnourished, in those predisposed to neuropathy (e.g., alcoholics and diabetics), and in adolescents.

See CLINICAL PHARMACOLOGY, General, for dosing information in patients with renal failure.

Adults

Patients should be given the following single daily dose of RIFATER either 1 hour before or 2 hours after a meal with a full glass of water.

Patients weighing ≤44 kg â€“ 4 tablets

Patients weighing between 45-54 kg â€“ 5 tablets

Patients weighing ≥55 kg â€“ 6 tablets

Pediatric Patients

The ratio of the drugs in RIFATER may not be appropriate in pediatric patients under the age of 15 (e.g., higher mg/kg doses of isoniazid are usually given in pediatric patients than adults).

HOW SUPPLIED

RIFATER tablets are light beige, smooth, round, and shiny sugar-coated tablets imprinted with “RIFATER” in black ink and contain 120 mg rifampin, 50 mg isoniazid, and 300 mg pyrazinamide, and are supplied as:

Bottles of 60 tablets (NDC 0088-0576-41).

Storage

Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature]. Protect from excessive humidity.

sanofi-aventis U.S. LLC Bridgewater, NJ 08807. Revised : May 2020

Side Effects

SIDE EFFECTS

Adverse Experiences During The Clinical Trial

Adverse event data reported for the RIFATER and the separate drug treatment groups during the first 2 months of the trial are shown in the table below.

Adverse Events Reported During the Clinical Study

Adverse Events by Body Systems During First 2 Months of Trial	Number of Patients with Adverse Events*
	RIFATER n=122‡	Separate†, n=123‡
Cutaneous (rash, erythroderma, erythema, exfoliative dermatitis, Lyell syndrome, urticaria, localized skin rash, diffuse skin rash, pruritus, generalized hypersensitivity)	8 (7%)	21 (17%)
Gastrointestinal (nausea, vomiting, digestive pain, diarrhea)	8 (7%)	14 (11%)
Musculoskeletal (arthralgia, long bones pain, phlebitis, localized joint pain, diffuse joint pain, edema of the legs)	5 (4%)	8 (7%)
Hearing and Vestibular (tinnitus, vertigo, vertigo with loss of equilibrium)	3 (2%)	6 (5%)
Liver and Biliary (hepatitis with conjunctival jaundice, hepatitis with deep jaundice)	0 (0%)	2 (2%)
Central and Peripheral Nervous System (sweating, headache, insomnia, diffuse paresthesia of the legs, anxiety, diabetic coma)	5 (4%)	4 (3%)
Total Body (spiking fever, persistent fever)	2 (2%)	4 (3%)
Cardiorespiratory (tightness in chest, coughing, diffuse chest pain, hemoptysis, angina, palpitation, total pneumothorax)	8 (7%)	3 (2%)
Total number of patients with one or more adverse events	29	43
* A given patient may have experienced ≥1 adverse event. † Isoniazid, rifampin, and pyrazinamide dosed as separate tablets and capsules. ‡ A total of 250 patients (124 RIFATER; 126 separate) were originally enrolled in the study. Five patients (2 RIFATER; 3 separate) were excluded due to admission errors.

No serious adverse events were reported in the patients receiving RIFATER tablets. Three serious adverse events were reported in the patients given isoniazid, rifampin, and pyrazinamide as separate tablets and capsules. The three serious adverse events were two general hypersensitivity reactions and one jaundice reaction.

There were no significant differences between the two treatment groups in standard liver function, renal function, and hematological laboratory test values measured at baseline and after 8 weeks of treatment. As would be expected for these drugs, there were alterations in liver enzymes (SGOT, SGPT) and serum uric acid levels. The adverse reactions reported during therapy with RIFATER are consistent with those described below for the individual components.

Adverse Reactions Reported For Individual Components Of RIFATER