Mycobutin
rifabutin
Pharmacologic class: Rifamycin derivative
Therapeutic class: Antimycobacterial
Pregnancy risk category B
Action
Inhibits RNA synthesis by blocking RNA transcription in susceptible organisms (mycobacteria and some gram-positive and gram-negative bacteria)
Availability
Capsules: 150 mg
Indications and dosages
➣ To prevent disseminated Mycobacterium avium intracellulare complex in patients with advanced human immunodeficiency virus (HIV) infection
Adults: 300 mg P.O. daily as a single dose or in two divided doses
Off-label uses
• Tuberculosis
• Prophylaxis and treatment of M. avium intracellulare in children
Contraindications
• Hypersensitivity to drug
• Active tuberculosis
Precautions
Use cautiously in:
• severe hepatic disease
• pregnant or breastfeeding patients.
Administration
• Give in divided doses twice daily with food to reduce GI upset.
Adverse reactions
CNS: headache, asthenia, weakness
CV: pressure sensation in chest
EENT: uveitis; discolored tears, saliva, or sputum
GI: nausea, vomiting, diarrhea, dyspepsia, abdominal pain, eructation, flatulence, discolored feces, anorexia
GU: discolored urine
Hematologic: eosinophilia, neutropenia, leukopenia, thrombocytopenia Musculoskeletal: joint pain, myalgia
Respiratory: dyspnea
Skin: rash, discolored skin or sweat
Other: abnormal taste, fever, flulike symptoms
Interactions
Drug-drug. Clarithromycin, itraconazole, saquinavir: reduced blood levels and efficacy of these drugs
Delavirdine: decreased delavirdine blood level, increased rifabutin blood level
Drugs metabolized by liver (such as zidovudine): altered blood levels of these drugs
Hormonal contraceptives: decreased contraceptive efficacy
Indinavir, nelfinavir, ritonavir: increased rifabutin blood level
Drug-diagnostic tests. Alanine aminotransferase, aspartate aminotransferase, eosinophils: increased levels
Neutrophils, platelets, white blood cells: decreased counts
Drug-food. High-fat foods: delayed drug absorption
Patient monitoring
• Monitor CBC with white cell differential. Watch for signs and symptoms of blood dyscrasias.
• Assess nutritional status.
• Closely monitor vital signs and temperature. Stay alert for dyspnea and flulike symptoms.
Patient teaching
• Advise patient to take twice daily with food (but not high-fat food) if GI upset occurs. To further minimize GI upset, teach him to eat small, frequent servings of healthy food and drink plenty of fluids.
• Instruct patient to take exactly as prescribed, even after symptoms subside.
See Tell patient to immediately report easy bruising or bleeding.
• Tell patient drug may turn tears, urine, and other body fluids reddish or brownish orange. Instruct him not to wear contact lenses during therapy because drug may stain them permanently.
• Inform patient that drug occasionally causes eye inflammation. Instruct him to report symptoms promptly.
• Caution patient to avoid driving and other hazardous activities until effects of drug are known.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.
rifabutin
(riff-a-byoo-tin) rifabutin,Mycobutin
(trade name)Classification
Therapeutic: agents atypical mycobacteriumIndications
Action
Therapeutic effects
Pharmacokinetics
Time/action profile (blood levels)
| ROUTE | ONSET | PEAK | DURATION |
|---|---|---|---|
| PO | rapid | 2–4 hr | 24 hr |
Contraindications/Precautions
Adverse Reactions/Side Effects
Ear, Eye, Nose, Throat
- brown-orange discoloration of tears (most frequent)
- ocular disturbances
Respiratory
- dyspnea
Cardiovascular
- chest pain
- chest pressure
Gastrointestinal
- pseudomembranous colitis (life-threatening)
- brown-orange discoloration of saliva (most frequent)
- altered taste
- drug-induced hepatitis
Genitourinary
- brown-orange discoloration of urine (most frequent)
Dermatologic
- rash
- skin discoloration
Hematologic
- hemolysis
- neutropenia
- thrombocytopenia
Musculoskeletal
- arthralgia
- myositis
Miscellaneous
- brown-orange discoloration of body fluids (most frequent)
- flu-like syndrome
Interactions
Drug-Drug interaction
Increases metabolism and may decrease the effectiveness of other drugs, including efavirenz, indinavir, nelfinavir, nevirapine, saquinavir (dosage adjustment may be necessary), delavirdine (concurrent use should be avoided), corticosteroids, disopyramide, quinidine, opioid analgesics, oral hypoglycemic agents, warfarin, estrogens, estrogen-containing contraceptives, phenytoin, verapamil, fluconazole, quinidine, theophylline, zidovudine, and chloramphenicol.Ritonavir increases blood levels of rifabutin (concurrent use is contraindicated), similar effects occur with efavirenz and nevirapine.Route/Dosage
Availability
Nursing implications
Nursing assessment
- Monitor patient for signs of active tuberculosis (purified protein derivative [PPD], chest x-ray, sputum culture, blood culture, urine culture, biopsy of suspicious lymph nodes) prior to and throughout therapy. Rifabutin must not be administered to patients with active tuberculosis.
- Monitor bowel function. Diarrhea, abdominal cramping, fever, and bloody stools should be reported to health care professional promptly as a sign of pseudomembranous colitis. May begin up to several weeks following cessation of therapy.
- Lab Test Considerations: Monitor CBC periodically during therapy. May cause neutropenia and thrombocytopenia.
Potential Nursing Diagnoses
Risk for infection (Indications)Noncompliance (Patient/Family Teaching)
Implementation
- Do not confuse rifabutin with rifampin.
- Oral: May be administered without regard to meals. High-fat meals slow rate but not extent of absorption. May be mixed with foods such as applesauce. If GI upset occurs, administer with food.
Patient/Family Teaching
- Advise patient to take medication as directed. Do not skip doses or double up on missed doses. Emphasize the importance of continuing therapy even if asymptomatic.
- Advise patient to notify health care professional promptly if signs and symptoms of neutropenia (sore throat, fever, signs of infection), thrombocytopenia (unusual bleeding or bruising), or hepatitis (yellow eyes and skin, nausea, vomiting, anorexia, unusual tiredness, weakness) occur.
- Caution patient to avoid the use of alcohol during this therapy, because this may increase the risk of hepatotoxicity.
- Instruct patient to notify health care professional immediately if diarrhea, abdominal cramping, fever, or bloody stools occur and not to treat with antidiarrheals without consulting health care professionals.
- Instruct patient to report symptoms of myositis (myalgia, arthralgia) or uveitis (intraocular inflammation) to health care professional promptly.
- Inform patient that saliva, sputum, sweat, tears, urine, and feces may become red-orange to red-brown and that soft contact lenses may become permanently discolored.
- Advise patient that this medication has teratogenic properties and may decrease the effectiveness of oral contraceptives. Counsel patient to use a nonhormonal form of contraception throughout therapy.
- Emphasize the importance of regular follow-up exams to monitor progress and to check for side effects.
Evaluation/Desired Outcomes
- Prevention of disseminated MAC in patients with advanced HIV infection.