Ampicillin

General

Ampicillin is an antibiotic in the beta-lactam family of antibiotics. It is a Penicillin derivative.

• Type: Penicillin
• Dosage Forms: capsule, oral suspension, powder for injection
• Dosage Strengths: capsule: 250, 500mg; oral suspension: 125, 250mg/5mL; powder for injection: 125mg, 250mg, 500mg, 1g, 2g, 10g
• Routes of Administration: PO, IV, IM
• Common Trade Names: Ampi, Omnipen, Penglobe, Principen

Adult Dosing

Endocarditis

• 12 g daily (continuous IV infusion or in 6 equally divided dosages) in conjunction with gentamicin

Perinatal Group B Streptococcal Prevention

• Initial 2 g dose at time of labor or rupture of membranes, followed by 1 g q4hrs until delivery

Pediatric Dosing

Pneumonia (peds)

• 150-200mg/kg/day IV divided Q6hours (max dose: 4g per day)

Other Pediatric Bacterial Infections

• 100-400mg/kg/day IM/IV divided q4-16Hours (max dose 12g/day IM/IV)

Special Populations

• Pregnancy Rating: B
• Lactation: Excreted in breastmilk, use caution
• Renal dosing:
  • CrCl <10 mL/min: Administer q12-24hr
  • CrCl 10-50 mL/min: Administer q6-12hr
  • CrCl >50 mL/min: Administer q6hr
• Hepatic Dosing: not studied

Contraindications

• Allergy to class/drug

Adverse Reactions

Serious

• Pseudomembranous colitis, enterocolitis
• Agranulocytosis
• Seizure
• Interstitial nephritis
• Stridor
• Anaphylaxis

Common

• Rash, urticaria
• Diarrhea, nausea
• Fever
• Oral candidiasis
• Stomatitis, glossitis
• Anemia/hemolytic anemia, leukopenia, thrombocytopenia, eosinophilia
• Serum sickness like reaction
• Elevated AST
• Erythema multiforme

Pharmacology

• Half-life: 1-1.8 hr (normal renal function); 7-20 hr (anuria/ESRD)
• Metabolism: Hepatic
• Excretion: Urine
• Mechanism of Action: Bactericidal; inhibits bacterial cell wall synthesis

Antibiotic Sensitivities

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

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

See Also

• Antibiotics (Main)