Penicillin (aminopenicillin)
Gram-positive: Streptococcus spp., Enterococcus spp., Listeria monocytogenes
Gram-negative: H. influenzae, E. coli, Proteus mirabilis, Salmonella spp., Shigella spp.
Exerts bactericidal activity via inhibition of bacterial cell wall synthesis by binding one or more of the penicillin binding proteins (PBPs). Exerts bacterial autolytic effect by inhibition of certain PBPs related to the activation of a bacterial autolytic process.
Penicillins produce time-dependent killing
Cmax: 7.5mcg/ml; Oral bioavailability: 80%; Half-life: 1-1.3h; Table 6
anemia, thrombocytopenia, neutropenia, agranulocytosis
seizures
nephrotoxicity, interstitial nephritis
transient increases in transaminases
Jarisch-Herxheimer Reaction (fever, chills, sweating, tachycardia, hyperventilation, flushing, and myalgia)
500mg po q12h or 250-500mg po q8h or 875mg po q12h
Pediatric: > 1 month and < 20 kg: 20-40 mg/kg/day in 3 divided doses
> 20 kg: usual adult dose
Renal failure: CrCL 10-50 mL/min: Consider extending dosing interval to q12h.
CrCL < 10 mL/min: Extend dosing interval to q12-24h.
Anaphylaxis amoxicillin or other penicillins
Acenocoumarin – increased risk of bleeding; Allopurinol – higher probablility of amoxicillin rash; Contraceptives - decreased contraceptive effectiveness; Live Typhoid Vaccine - decreased immunological response to the typhoid vaccine; Methotrexate – methotrexate toxicity; Probenecid - increased amoxicillin levels; Warfarin – increased risk of bleeding
Category B: No evidence of risk in humans but studies inadequate.
Therapeutic: Culture and sensitivities, signs and symptoms of infection
Toxic: Periodic CBC, urinalysis, BUN, Creatinine, AST and ALT, diarrhea, skin rash
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