Rifampin (Page 3 of 5)

Information for Patients

Patients should be counseled that antibacterial drugs including rifampin should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When rifampin is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by rifampin or other antibacterial drugs in the future.

The patient should be told that rifampin may produce a discoloration (yellow, orange, red, brown) of the teeth, urine, sweat, sputum, and tears, and the patient should be forewarned of this. Soft contact lenses may be permanently stained.

Rifampin is a well characterized and potent inducer of drug metabolizing enzymes and transporters and might therefore decrease or increase concomitant drug exposure and impact safety and efficacy (see DRUG INTERACTIONS). Therefore, patients should be advised not to take any other medication without medical advice.

The patient should be advised that the reliability of oral or other systemic hormonal contraceptives may be affected; consideration should be given to using alternative contraceptive measures.

Patients should be instructed to take rifampin either 1 hour before or 2 hours after a meal with a full glass of water.

Patients should be instructed to notify their physician immediately if they experience any of the following: rash with fever or blisters, with or without peeling skin, itching, or swollen lymph nodes, loss of appetite, malaise, nausea, vomiting, abdominal pain, darkened urine, yellowish discoloration of the skin and eyes, light-colored bowel movements, fever, headache, fatigue, myalgias, cough, shortness of breath, chest pain, wheezing and pain or swelling of the joints.

Patients should be advised to seek medical advice immediately if their symptoms of mycobacterial disease, including, but not limited to, cough, fever, tiredness, shortness of breath, malaise, headache, pain, night sweats, swollen lymph nodes, loss of appetite, weight loss, weakness, skin ulcers or lesions, worsen (see ADVERSE REACTIONS).

Advise patients to abstain from alcohol, hepatotoxic medications or herbal products while taking rifampin.

Compliance with the full course of therapy must be emphasized, and the importance of not missing any doses must be stressed.

Laboratory Tests

Adults treated for tuberculosis with rifampin should have baseline measurements of hepatic enzymes, bilirubin, serum creatinine, a complete blood count, and a platelet count (or estimate). Baseline tests are unnecessary in pediatric patients unless a complicating condition is known or clinically suspected.

Patients should be seen at least monthly during therapy and should be specifically questioned concerning symptoms associated with adverse reactions. All patients with abnormalities should have follow-up, including laboratory testing, if necessary. Routine laboratory monitoring for toxicity in people with normal baseline measurements is generally not necessary.

Drug Interactions

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. Therefore, concomitant use of these medications is contraindicated. (See CONTRAINDICATIONS.)

When rifampin is given concomitantly with other hepatotoxic medications such as halothane or isoniazid, the potential for hepatotoxicity is increased. The concomitant use of rifampin and halothane should be avoided. Patients receiving both rifampin and isoniazid should be monitored closely for hepatotoxicity.

Effect of rifampin on other drugs

Induction of Drug Metabolizing Enzymes and Transporters

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 coadministered 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 Concentrations^a

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
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
Tipranavir	Substantial decrease in exposure, which may result in loss of therapeutic effect and development of resistance.
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 rifampin, 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 rifampin therapy
Estrogens	Decrease exposure
Progestins
Anticonvulsants
Phenytoind	Decrease exposured
Antiarrhythmics
Disopyramide	Decrease exposure
Mexiletine	Decrease exposure
Quinidine	Decrease exposure
Propafenone	Decrease AUC by 50% to 67%
Tocainide	Decrease exposure
Antiestrogens
Tamoxifen	Decrease AUC by 86%
Toremifene	Decrease steady state concentrations of toremifene in serum
Antithrombotic Agents
ClopidogrelPrevention 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%
LurasidonePrevention or Management: Concomitant use is contraindicated (See CONTRAINDICATIONS)	Decrease exposure
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%
Zolpidem	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 rifampin. Continue monitoring and increase digoxin dose by approximately 20% to 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 Rifampin 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 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	Rifampin has been shown to increase the clearance of dapsone and, accordingly, decrease dapsone exposure. Rifampin has also been shown to increase the production of the hydroxylamine metabolite of dapsone which could increase the risk of methemoglobinemia
Doxycyclinek	Decrease exposure
Irinotecanl Prevention or Management: Avoid the use of rifampin, 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.
Praziquantel Prevention or Management: Concomitant use is contraindicated (See CONTRAINDICATIONS)	Decrease plasma praziquantel concentrations to undetectable levels.
Quinine Prevention or Management: Avoid concomitant use	Decrease AUC by 75% to 85%
Telithromycin	Decrease AUC by 86%
Theophylline	Decrease exposure by 20% to 40%