Rifampin

General

• Type: bactericidal antibiotic
• Dosage Forms: 150, 300; PO, IV
• Common Trade Names: Rifadin

Pharmacology

• Half-life: 1.5-5hours (increased if there is hepatic dysfunction)
  • Rifampin autoinduces its own metabolism so half-life is decreased with subsequent dosing.
• Metabolism: Hepatic
• Excretion: Bile; Urine <30%
• Mechanism of Action: inhibits bacterial RNA synthesis

Adult Dosing

Active TB

• 10mg/kg/day (in combination with isoniazid and pyrazinamide) PO or IV for 2 months
  • Then 10mg/kg/day (in combination with isoniazid) for 4 months or longer as needed
  • MAX, 600mg/day

Inactive TB, HIV+

• 600mg PO daily for 4 months

Meningitis

• 600mg IV once daily (with vancomycin/cephalosporin)

Meningococcal Prophylaxis

• 600 mg PO BID for two days

Bartonellosis

• 300mg PO or IV q12h plus doxycycline

Brucellosis

• 15-20mg/kg/day PO/IV in 1 or 2 divided doses for at least 6 weeks in combination with a tetracycline
  • MAX 600 to 900mg/day

Infective endocarditis

• 300mg IV or PO every 8 hours for a minimum of 6 weeks, in combination with appropriate antimicrobial therapy

Hansen Disease

• Paucibacillary, single lesion
  • 600 mg PO x1 with ofloxacin and minocycline
• Paucibacillary
  • 600 mg PO qmo x 6mo with dapsone
• Multibacillary
  • 600 mg PO qmo x 12mo with dapsone and clofazimine

Anthrax, systemic

• 600 mg IV q12h for at least 2 wk as part of a multi-drug regimen
  • Switch to PO abx x60 days total if inhalational exposure

Pediatric Dosing

Active TB

• <15 yo
  • 10-20 mg/kg PO/IV qd for at least 6mo
    • Max: 600 mg/day
• 15+ yo
  • 10 mg/kg PO/IV qd for at least 6mo
    • Max: 600 mg/day

Latent TB

• <15 yo
  • 10-20 mg/kg PO/IV qd x4mo
    • Max: 600 mg/day
• 15+ yo
  • 10 mg/kg PO/IV qd x4mo
    • Max: 600 mg/day

H. influenza prophylaxis

• <1 mo
  • 10mg/kg PO/IV q24h x4 days
    • Max: 600 mg/day
• 1+ mo
  • 20 mg/kg PO/IV q24h x4 days
  • Max: 600 mg/day

Meningcococcal prophylaxis

• <1 mo
  • 5mg/kg PO/IV q24h x4 days
    • Max: 600 mg/day
• 1+ mo
  • 10 mg/kg PO/IV q24h x4 days
  • Max: 600 mg/day

Endocarditis, Staphylococcal prosthetic valve

• 20 mg/kg/day PO/IV divided q8h for at least 6wk with gentamicin and nafcillin
  • Max 900 mg/day

Hansen Disease

• Paucibacillary, 10-14 yo
  • 450mg PO qmo x6mo with dapsone
• Paucibacillary, 15+ yo
  • 600 mg PO qmo x 6mo with dapsone
• Multibacillary, 10-14 yo
  • 450mg PO qmo x 12mo with dapsone and clofazimine
• Multibacillary, 15+ yo
  • 600 mg PO qmo x 12mo with dapsone and clofazimine

Anthrax, systemic

• Neonates >32 wk gestation
  • 10-20 mg/kg/day IV divided q12-24h for at least 2 wk as part of multi-drug regimen
• 1+ mo
  • 20 mg/kg/day IV divided q12h for at least 2 wk as part of multi-drug regimen
    • Max: 300 mg/dose

Special Populations

• Pregnancy Rating: C
• Lactation: Infant risk minimal
• Renal Dosing:
  • Adult
    • CrCl <50: Consider decreasing dose 0-50%
    • HD/PD: No supplment
  • Pediatric
    • CrCl <50: Consider decreasing dose 0-50%
    • HD/PD: No supplment
• Hepatic Dosing
  • Adult
    • Avoid Use
  • Pediatric
    • Avoid Use

Contraindications

• Allergy to class/drug
• IM or SC administration
• Concomitant use with atazanavir, darunavir, fosamprenavir, saquinavir, tipranavir, rilpivirine or elvitegravir/cobicistat

Adverse Reactions

Serious

• Agranulocytosis
• DIC
• Hepatotoxicity
• Nephrotoxicity
• Thrombocytopenia
• Leukopenia
• Anemia
• Porphyria exacerbation
• Erythema multiforme
• Stevens-Johnson Syndrome
• Toxic epidermal necrolysis
• C. Diff associated diarrhea
• Psychosis
• Uveitis

Common

• Reddish-Orange body fluids
• Nausea/vomiting
• Diarrhea
• Headache
• Dizziness
• Fatigue
• Disequilibrium
• Weakness
• Pruritus
• Flushing
• Anorexia
• Abdominal pain
• Dyspnea
• Contact lens staining

Acute Overdose

• Diarrhea is unique to rifampin toxicity in comparison to other antituberculous medications

Antibiotic Sensitivities

Group	Organism	Sensitivity
Gram Positive	Strep. Group A, B, C, G	S
	Strep. Pneumoniae	S
	Viridans strep	X1
	Strep. anginosus gp	X1
	Enterococcus faecalis	I
	Enterococcus faecium	R
	MSSA	S
	MRSA	S
	CA-MRSA	S
	Staph. Epidermidis	S
	C. jeikeium	S
	L. monocytogenes	S
Gram Negatives	N. gonorrhoeae	X2
	N. meningitidis	S
	Moraxella catarrhalis	S
	H. influenzae	S
	E. coli	R
	Klebsiella sp	R
	E. coli/Klebsiella ESBL+	R
	E coli/Klebsiella KPC+	I
	Enterobacter sp, AmpC neg	R
	Enterobacter sp, AmpC pos	R
	Serratia sp	X1
	Serratia marcescens	R
	Salmonella sp	R
	Shigella sp	R
	Proteus mirabilis	X1
	Proteus vulgaris	R
	Providencia sp.	X1
	Morganella sp.	X1
	Citrobacter freundii	X1
	Citrobacter diversus	X1
	Citrobacter sp.	X1
	Aeromonas sp	X1
	Acinetobacter sp.	R
	Pseudomonas aeruginosa	R
	Burkholderia cepacia	R
	Stenotrophomonas maltophilia	X1
	Yersinia enterocolitica	X1
	Francisella tularensis	S
	Brucella sp.	S+'
	Legionella sp.	X1
	Pasteurella multocida	X1
	Haemophilus ducreyi	X1
	Vibrio vulnificus	X1
Misc	Chlamydophila sp	X2
	Mycoplasm pneumoniae	X1
	Rickettsia sp	X1
	Mycobacterium avium	X1
Anaerobes	Actinomyces	X1
	Bacteroides fragilis	X1
	Prevotella melaninogenica	X1
	Clostridium difficile	X1
	Clostridium (not difficile)	X1
	Fusobacterium necrophorum	X1
	Peptostreptococcus sp.	X1

Key

• S susceptible/sensitive (usually)
• I intermediate (variably susceptible/resistant)
• R resistant (or not effective clinically)
• S+ synergistic with cell wall antibiotics
• U sensitive for UTI only (non systemic infection)
• X1 no data
• X2 active in vitro, but not used clinically
• X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
• X4 active in vitro, but not clinically effective for strep pneumonia