Rifater

Last updated on RxList: 6/30/2021
Rifater Side Effects Center

What Is Rifater?

Rifater (rifampin, isoniazid and pyrazinamide) is a combination of antibiotics used to treat tuberculosis (TB).

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.

Tell your doctor if you have unlikely but serious side effects of Rifater include:

  • painful or swollen joints,
  • changes in the amount of urine,
  • increased thirst or urination,
  • bloody urine,
  • vision changes,
  • fast heartbeat,
  • easy bruising or bleeding,
  • signs of a new infection (such as fever, persistent sore throat),
  • mental/mood changes (such as confusion, psychosis), or
  • seizures.

Dosage for Rifater

Rifater is recommended in the initial phase of short-course therapy, which is usually continued for 2 months. Dose is determined by the patient's body weight.

What Drugs, Substances, or Supplements Interact with Rifater?

Rifater may interact with cyclosporine, haloperidol, nortriptyline, probenecid, theophylline, antibiotics, antifungal medications, barbiturates, birth control pills or hormone replacement therapy, blood thinners, oral diabetes medications, heart or blood pressure medications, heart rhythm medications, narcotics, sedatives, seizure medications, steroids, or sulfa drugs. Many other medicines can interact with Rifater.

Rifater During Pregnancy and Breastfeeding

Tell your doctor all prescription and over-the-counter medications you use. During pregnancy, Rifater should be used only when prescribed. When rifampin is taken during the last few weeks of pregnancy, the risk of bleeding in both mother and infant may be increased. Tell your doctor if you notice any bleeding in your newborn. This medication passes into breast milk but the effect on a nursing infant is unknown. Consult your doctor before breastfeeding.

Additional Information

Our Rifater (rifampin, isoniazid and pyrazinamide) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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Rifater Consumer Information

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Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, and joint pain or stiffness.

Rifater can cause severe liver symptoms, especially in people who are 35 and older. Call your doctor at once if you have any of these early signs of liver damage: nausea, vomiting, upper stomach pain, weakness, tiredness, loss of appetite, or yellowing of your skin or eyes.

Also call your doctor right away if you have:

  • numbness, tingling, or burning pain in your hands or feet;
  • vision problems, pain behind your eyes;
  • wheezing, trouble breathing; or
  • severe stomach pain, diarrhea that is watery or bloody.

Common side effects may include:

  • numbness or tingling;
  • red discoloration of your teeth, sweat, urine, saliva, and tears;
  • nausea, vomiting, stomach pain;
  • mild rash or itching; or
  • joint or muscle pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Rifater (Rifampin, Isoniazid and Pyrazinamide)

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Rifater Professional Information

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

Rifampin

Gastrointestinal

Heartburn, epigastric distress, anorexia, nausea, vomiting, jaundice, flatulence, cramps, and diarrhea have been noted in some patients. Although Clostridium difficile has been shown in vitro to be sensitive to rifampin, pseudomembranous colitis has been reported with the use of rifampin (and other broad-spectrum antibiotics). Therefore, it is important to consider this diagnosis in patients who develop diarrhea in association with antibiotic use. Tooth discoloration (which may be permanent) may occur.

Hepatic

Hepatotoxicity including transient abnormalities in liver function tests (e.g., elevations in serum bilirubin, alkaline phosphatase, serum transaminases, gamma-glutamyl transferase), hepatitis, a shock-like syndrome with hepatic involvement and abnormal liver function tests, and cholestasis have been reported (see WARNINGS).

Hematologic

Thrombocytopenia has occurred primarily with high dose intermittent therapy but has also been noted after resumption of interrupted treatment. It rarely occurs during well-supervised daily therapy. This effect is reversible if the drug is discontinued as soon as purpura occurs. Cerebral hemorrhage and fatalities have been reported when rifampin administration has been continued or resumed after the appearance of purpura.

Rare reports of disseminated intravascular coagulation have been observed.

Leukopenia, hemolytic anemia, decreased hemoglobin, bleeding, and vitamin K–dependent coagulation disorders (abnormal prolongation of prothrombin time or low vitamin K–dependent coagulation factors) have been observed.

Agranulocytosis has been reported rarely.

Central Nervous System

Headache, fever, drowsiness, fatigue, ataxia, dizziness, inability to concentrate, mental confusion, behavioral changes, muscular weakness, pains in extremities, and generalized numbness have been observed.

Psychoses have been rarely reported.

Rare reports of myopathy have also been observed.

Ocular

Visual disturbances have been observed.

Endocrine

Menstrual disturbances have been observed.

Rare reports of adrenal insufficiency in patients with compromised adrenal function have been observed.

Renal

Elevations in BUN and serum uric acid have been reported. Rarely, hemolysis, hemoglobinuria, hematuria, interstitial nephritis, acute tubular necrosis, renal insufficiency, and acute renal failure have been noted. These are generally considered to be hypersensitivity reactions. They usually occur during intermittent therapy or when treatment is resumed following intentional or accidental interruption of a daily dosage regimen and are reversible when rifampin is discontinued and appropriate therapy instituted.

Dermatologic

Cutaneous reactions are mild and self-limiting and do not appear to be hypersensitivity reactions. Typically, they consist of flushing and itching with or without a rash. More serious cutaneous reactions which may be due to hypersensitivity occur but are uncommon.

Hypersensitivity Reactions

Occasionally pruritus, urticaria, rash, pemphigoid reaction, erythema multiforme, acute generalized exanthematous pustulosis, Stevens-Johnson syndrome, toxic epidermal necrolysis, Drug Reaction with Eosinophilia and Systemic Symptoms syndrome (see WARNINGS), vasculitis, eosinophilia, sore mouth, sore tongue, and conjunctivitis have been observed.

Anaphylaxis has been reported rarely.

Miscellaneous

Edema of the face and extremities has been reported. Other reactions which have occurred with intermittent dosage regimens include “flu” syndrome (such as episodes of fever, chills, headache, dizziness, and bone pain), shortness of breath, wheezing, decrease in blood pressure and shock. The “flu” syndrome may also appear if rifampin is taken irregularly by the patient or if daily administration is resumed after a drug-free interval.

Isoniazid

The most frequent reactions are those affecting the nervous system and the liver. (See the BOX WARNING.)

Nervous System

Peripheral neuropathy is the most common toxic effect. It is dose-related, occurs most often in the malnourished and in those predisposed to neuritis (e.g., alcoholics and diabetics), and is usually preceded by paresthesia of the feet and hands. The incidence is higher in “slow inactivators.”

Other neurotoxic effects, which are uncommon with conventional doses, are convulsions, toxic encephalopathy, optic neuritis and atrophy, memory impairment, and toxic psychosis.

Gastrointestinal

Pancreatitis, nausea, vomiting, and epigastric distress.

Hepatic

Elevated serum transaminases (SGOT, SGPT), bilirubinemia, bilirubinuria, jaundice, and occasionally severe and sometimes fatal hepatitis. The common prodromal symptoms are anorexia, nausea, vomiting, fatigue, malaise, and weakness. Mild and transient elevation of serum transaminase levels occurs in 10 to 20% of persons taking isoniazid. The abnormality usually occurs in the first 4 to 6 months of treatment but can occur at any time during therapy. In most instances, enzyme levels return to normal with no necessity to discontinue medication. In occasional instances, progressive liver damage occurs, with accompanying symptoms. In these cases, the drug should be discontinued immediately. The frequency of progressive liver damage increases with age. It is rare in persons under 20 but occurs in up to 2.3% of those over 50 years of age.

Hematologic

Agranulocytosis; hemolytic, sideroblastic, or aplastic anemia; thrombocytopenia; and eosinophilia.

Hypersensitivity Reactions

Fever, skin eruptions (morbilliform, maculopapular, purpuric, or exfoliative), lymphadenopathy, anaphylactic reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis (see WARNINGS, Isoniazid), Drug Reaction with Eosinophilia and Systemic Symptoms syndrome (see WARNINGS), and vasculitis.

Metabolic and Endocrine

Pyridoxine deficiency, pellagra, hyperglycemia, metabolic acidosis, and gynecomastia.

Miscellaneous

Rheumatic syndrome and systemic lupus erythematosus-like syndrome.

Pyrazinamide

The principal adverse effect is a hepatic reaction (see WARNINGS). Hepatotoxicity appears to be dose related and may appear at any time during therapy. Pyrazinamide can cause hyperuricemia and gout (see PRECAUTIONS).

Gastrointestinal

GI disturbances including nausea, vomiting, and anorexia have also been reported.

Hematologic and Lymphatic

Thrombocytopenia and sideroblastic anemia with erythroid hyperplasia, vacuolation of erythrocytes and increased serum concentration have occurred rarely with this drug. Adverse effects on blood clotting mechanisms have also been rarely reported.

Other

Mild arthralgia and myalgia have been reported frequently. Hypersensitivity reactions including Drug Reaction with Eosinophilia and Systemic Symptoms syndrome (see WARNINGS), rashes, urticaria, pruritus, and erythema have been reported. Angioedema has been reported rarely. Fever, acne, photosensitivity, porphyria, dysuria, and interstitial nephritis have been reported rarely.

DRUG INTERACTIONS

The Individual Components Of RIFATER

There were no drug-drug interaction trials conducted with RIFATER.

Information regarding potential drug interactions with the individual components of RIFATER are provided below. These recommendations include quantitative clinical effects based on drug interaction trials, qualitative effects noted in the primary literature, or predicted interactions due to the expected magnitude of interaction and potential for serious adverse events or loss of efficacy. [See CONTRAINDICATIONS.]

Rifampin And Isoniazid

Cytochrome P450 Enzyme Interaction

Rifampin is known to induce, and isoniazid is known to inhibit certain cytochrome P450 enzymes. In general, the impact of the competing effects of rifampin and isoniazid on the metabolism of drugs that undergo biotransformation through the affected pathways is unknown. Therefore, caution should be used when prescribing RIFATER with drugs metabolized by cytochrome P450. To maintain optimum therapeutic blood concentrations, dosages of drugs metabolized by these enzymes may require adjustment when starting or stopping RIFATER.

Rifampin

Pharmacodynamic Interactions

Healthy subjects who received rifampin, 600 mg once daily concomitantly with saquinavir 1000 mg/ritonavir 100 mg twice daily (ritonavir-boosted saquinavir) developed severe hepatocellular toxicity. Concomitant use of ritonavir-boosted saquinavir and RIFATER is contraindicated. (See CONTRAINDICATIONS.)

When rifampin is given concomitantly with other hepatotoxic medications such as halothane or isoniazid, the potential for hepatotoxicity is increased. Avoid concomitant use of RIFATER with halothane. Monitor patients receiving RIFATER for hepatotoxicity. (See the BOX WARNING.)

Effect of Rifampin on Other Drugs

Induction of Drug Metabolizing Enzymes and Transporter Systems

Drug metabolizing enzymes and transporters affected by rifampin include cytochromes P450 (CYP) 1A2, 2B6, 2C8, 2C9, 2C19, and 3A4, UDP-glucuronyltransferases (UGT), sulfotransferases, carboxylesterases, and transporters including P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (MRP2). Most drugs are substrates for one or more of these enzyme or transporter pathways and these pathways may be induced by rifampin simultaneously. Therefore, rifampin may increase the metabolism and decrease the activity of certain concomitantly used drugs or increase the activity of a coadministered pro-drug (where metabolic activation is required) and has the potential to perpetuate clinically important drug-drug interactions against many drugs and across many drug classes (Table 1).

Table 1 summarizes the effect of rifampin on other drugs or drug classes. Adjust dosages of concomitant drugs based on approved drug labeling and if applicable, therapeutic drug monitoring, unless otherwise specified.

Table 1: Drug Interactions with Rifampin that Affect Concomitant Drug Concentrationsa

Drug or Drug Class and Prevention or Management Clinical Effect
Antiretrovirals
Prevention or Management: Concomitant use is contraindicated (See CONTRAINDICATIONS)
Atazanavir Decrease AUC by 72%
Darunavirb Substantial decrease in exposure, which may result in loss of therapeutic effect and development of resistance.
Tipranavir
Fosamprenavirc Decrease AUC by 82%
Saquinavir Decrease AUC by 70% Coadministration may result in severe hepatocellular toxicity
Antiretrovirals
Prevention or Management: Avoid concomitant use
Zidovudine Decrease AUC by 47%
Indinavir Decrease AUC by 92%
Efavirenz Decrease AUC by 26 %
Hepatitis C Antiviral
Prevention or Management: Avoid concomitant use
Daclatasvir Decrease AUC by 79%
Simeprevir Decrease AUC by 48%
Sofosbuvirb Decrease AUC by 72% Coadministration of sofosbuvir with RIFATER may decrease sofosbuvir plasma concentrations, leading to reduced therapeutic effect of sofosbuvir.
Telaprevir Decrease AUC by 92%
Systemic Hormonal Contraceptives
Prevention or Management: Advise patients to change to non-hormonal methods of birth control during treatment with RIFATER, which contains rifampin
Estrogens Decrease exposure
Progestins
Anticonvulsants
Phenytoind Decrease exposured
Antiarrhythmics
Disopyramide Decrease exposure
Mexiletine Decrease exposure
Quinidine Decrease exposure
Propafenone Decrease AUC by 50%-67%
Tocainide Decrease exposure
Antiestrogens
Tamoxifen Decrease AUC by 86%
Toremifene Decrease steady state concentrations of toremifene in serum
Antithrombotic Agents
Clopidogrel
Prevention or Management: Concomitant use of clopidogrel and rifampin should be discouraged
Increase active metabolite exposure and risk of bleeding
Ticagrelor
Prevention or Management: Avoid use
Decrease exposure
Antipsychotics
Haloperidol Decrease plasma concentrations by 70%
Oral Anticoagulants
Prevention or Management: Perform prothrombin time daily or as frequently as necessary to establish and maintain the required dose of anticoagulant
Warfarin Decrease exposure
Antifungals
Fluconazole Decrease AUC by 23%
Itraconazole Prevention or Management: Not recommended 2 weeks before and during itraconazole treatment Decrease exposure
Ketoconazole Decrease exposure
Beta-blockers
Metoprolol Decrease exposure
Propranolol Decrease exposure
Benzodiazepines
Diazepama,e Decrease exposure
Benzodiazepine-related drugs
Zopiclone Decrease AUC by 82%
Zopiclone Decrease AUC by 73%
Calcium Channel Blockerse
Diltiazem Decrease exposure
Nifedipinef Decrease exposure
Verapamil Decrease exposure
Corticosteroidsg
Prednisolone Decrease exposure
Cardiac Glycosides
Digoxin
Prevention or Management: Measure serum digoxin concentrations before initiating RIFATER, which contains rifampin. Continue monitoring and increase digoxin dose by approximately 20%-40% as necessary.
Decrease exposure
Digitoxin Decrease exposure
Fluoroquinolones
Pefloxacinh Decrease exposure
Moxifloxacina,d Decrease exposure
Oral Hypoglycemic Agents (e.g., sulfonylureas)
Glyburide Decrease exposure Coadministration of glyburide with RIFATER may worsen glucose control of glyburide
Glipizide Decrease exposure
Immunosuppressive Agents
Cyclosporine Decrease exposure
Tacrolimus
Prevention or Management: Monitoring of whole blood concentrations and appropriate dosage adjustments of tacrolimus are recommended when RIFATER, which contains rifampin, and tacrolimus are used concomitantly.
Decrease AUC by 56%
Narcotic Analgesics
Oxycodone Decrease AUC by 86%
Morphine Decrease exposure
Selective 5-HT3 Receptor Antagonists
Ondansetron Decrease exposure
Statins Metabolized by CYP3A4
Simvastatin Decrease exposure
Thiazolidinediones
Rosiglitazone Decrease AUC by 66%
Tricyclic Antidepressants
Nortriptylinei Decrease exposure
Other Drugs
Enalapril Decrease active metabolite exposure
Chloramphenicolj Decrease exposure
Clarithromycin Decrease exposure
Dapsone Decrease exposure
Doxycyclinek Decrease exposure
Irinotecanl
Prevention or Management: Avoid the use of RIFATER (which contains rifampin, a strong CYP3A4 inducer) if possible. Substitute non-enzyme inducing therapies at least 2 weeks prior to initiation of irinotecan therapy
Decrease irinotecan and active metabolite exposure
Levothyroxine Decrease exposure
Losartan Parent Decrease AUC by 30%
Active metabolite (E3174) Decrease AUC by 40%
Methadone In patients well-stabilized on methadone, concomitant administration of rifampin resulted in a marked reduction in serum methadone levels and a concurrent appearance of withdrawal symptoms.Decrease AUC by 30%
Praziquantel
Prevention or Management: Concomitant use is contraindicated (See CONTRAINDICATIONS)
Decrease plasma praziquantel concentrations to undetectable levels.Active metabolite (E3174)Decrease AUC by 40%
Quinine
Prevention or Management: Avoid concomitant use
Decrease AUC by 75%-85%
Telithromycin Decrease AUC by 86%
Theophylline Decrease exposure by 20% to 40%
a Administered with rifampin 600 mg daily, unless otherwise specified
b Rifampin dosage used concomitantly with the drug(s) is not specified in the proposed package insert.
c Administered with rifampin 300 mg daily
d Administered with rifampin 450 mg daily
e Administered with rifampin 1200 mg daily
f Rifampin 1200 mg administered as a single oral dose 8 hours before administering a single oral dose of nifedipine 10 mg
g Numerous cases in the literature describe a decrease in glucocorticoid effect when used concomitantly with rifampin. The literature contains reports of acute adrenal crisis or adrenal insufficiency induced by the combination of rifampin-isoniazid-ethambutol or rifampin-isoniazid in patients with Addison’s disease.
h Administered with rifampin 900 mg daily
i A tuberculosis treatment regimen including rifampin (600 mg/day), isoniazid (300 mg/day), pyrazinamide (500 mg 3× per day), and pyridoxine (25 mg) was associated with higher than expected doses of nortriptyline were required to obtain a therapeutic drug level. Following the discontinuation of rifampin, the patient became drowsy and the serum nortriptyline levels rose precipitously (3-fold) into the toxic range.
j Concomitant use with rifampin in 2 children
k Administered with rifampin (10 mg/kg daily)
l Administered with an antibiotic regimen including rifampin (450 mg/day), isoniazid (300 mg/day), and streptomycin (0.5 g/day) IM
AUC = area under the time-concentration curve

Effect of Other Drugs on Rifampin

Concomitant use with antacids may reduce the absorption of rifampin which may reduce the efficacy of RIFATER. Administer RIFATER at least 1 hour before the ingestion of antacids.

Concomitant use with probenecid and cotrimoxazole increases the concentration of rifampin which may increase the risk of RIFATER toxicities. Monitor for adverse reactions associated with RIFATER during coadministration.

Other Interactions

Atovaquone

Concomitant use of RIFATER with atovaquone decrease concentrations of atovaquone and increase concentrations of rifampin which may increase the risk of RIFATER toxicities. Coadministration of RIFATER with atovaquone is not recommended.

Isoniazid

Pharmacodynamic Interactions

Concomitant use with daily ingestion of alcohol may be associated with a higher incidence of isoniazid hepatitis. Concomitant use of isoniazid with rifampin may increase the hepatotoxicity of both drugs. Monitor patients receiving both rifampin and isoniazid as in RIFATER for hepatotoxicity.

Concomitant use may exaggerate the CNS effects of meperidine (drowsiness), cycloserine (dizziness, drowsiness), and disulfiram (acute behavioral and coordination changes).

Concomitant use with levodopa may produce symptoms of excess catecholamine stimulation (agitation, flushing, palpitations) or lack of levodopa effect.

Concomitant use with oral hypoglycemics may produce hyperglycemia and lead to loss of glucose control.

Concomitant use with enflurane may produce high concentrations of hydrazine that facilitate defluorination of enflurane due to fast acetylation of isoniazid. Monitor renal function.

Pharmacokinetic Interactions

Effect of Isoniazid on Other Drugs

Inhibition of drug metabolizing enzymes

Isoniazid, a component of RIFATER, is known to inhibit certain cytochrome P-450 enzymes (e.g., CYP1A2, CYP2C9, CYP2C19, CYP3A4). Concomitant use may decrease elimination of drugs metabolized by these enzymes which may increase the risk of toxicities of these drugs. Adjust dosages of drugs metabolized by these enzymes based on approved drug labeling and if applicable, therapeutic drug monitoring.

Isoniazid has been reported to inhibit the metabolism of the following drugs: anticonvulsants (e.g., carbamazepine, phenytoin, primidone, valproic acid), benzodiazepines (e.g., diazepam), haloperidol, ketoconazole, theophylline, and warfarin. Therefore, isoniazid may increase the risk of toxicities of these drugs. However, as RIFATER contains both isoniazid (inhibitor) and rifampin (inducer), the effect on the metabolism of the above listed drugs when used concomitantly with RIFATER is unknown. A potential for increased toxicity cannot be excluded. Monitor closely for adverse reactions.

Other Interactions

Antacid: Concomitant use with antacid may reduce the absorption of isoniazid which may reduce RIFATER efficacy. Administer RIFATER at least 1 hour before use of antacids.

Corticosteroids: Concomitant use with corticosteroids (e.g., prednisolone) may decrease the serum concentration of isoniazid by increasing acetylation rate and/or renal clearance which may reduce RIFATER efficacy.

Para-aminosalicylic acid: Concomitant use with para-aminosalicylic acid may increase the plasma concentration and elimination half-life of isoniazid by competition of acetylating enzymes which may increase the risk of RIFATER toxicities.

Read the entire FDA prescribing information for Rifater (Rifampin, Isoniazid and Pyrazinamide)

© Rifater Patient Information is supplied by Cerner Multum, Inc. and Rifater Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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