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penicillin
In general, low toxicity. Most common agents along with cephalosporins implicated in drug allergies.
Indications:
1) oral: mild to moderately severe penicillin-sensitive infections
2) parenteral: severe penicillin-sensitive infections or when GI tract is not an acceptable route of administration
3) treatment of sensitive gonorrhea
4) treatment of choice for syphilis
Antimicrobial activity:
1) mostly gram positive bacteria
2) some gram negative coverage
3) some anaerobic coverage
Antibiotic resistance
1) beta-lactamase production
a) penicillin-resistant Staphylococcus
b) Haemophilus
c) anaerobes
d) aerobic gram-negative bacteria
2) alterations in penicillin-binding proteins
a) methicillin-resistant Staphylococcus aureus (MRSA)
b) Streptococci
c) Neisseria
d) Enterococci
Dosage:
1) oral (Pen VK) 250-500 mg every 6 hours
2) benzathine (IM) 600,000- 2,400,000 units IM weekly
3) procaine (IM) 600,000- 2,400,000 units IM QD
Dosage adjustment in renal failure: (Pen G)
creatinine clearance dosage*
> 30 mL/min 1-2 x 10E6 units IV every 4 hours
10-30 mL/min 1-2 x 10E6 units IV every 6 hours
< 10 mL/min 1-2 x 10E6 units IV every 12 hours
post-dialysis 2 x 10E6 units
* higher doses (3-4 x 10E6 units) should be considered for streptococcal endocarditis or pneumococcal meningitis
Pharmacokinetics:
1) penicillin V (oral)
a) 60% absorbed
b) food reduces or delays absorption
c) should be taken on an empty stomach
2) benzathine (IM) & procaine (IM) penicillin
- slow depot absorption
3) widely distributed in body fluids, tissues & cavities
4) poor CSF penetration (doses of > 20 x 10E6 units/day used to treat meningitis)
5) 60-70% eliminated in the urine
6) minimal hepatic metabolism with excretion in the bile
7) penicillin G is removed by hemodialysis
8) elimination 1/2life
a) normally 30-40 minutes
b) up to 7-10 hours in patients with renal failure
c) up to 7-10 hours in patients with renal & hepatic failure
Adverse effects:
1) hypersensitivity
a) IgE-mediated
b) anaphylaxis may occur
c) desensitization is hazardous
2) electrolyte disturbances
a) hypernatremia
b) hyperkalemia
c) hyperchloremic alkalosis
3) dose-related neurotoxicity
4) nausea/vomiting
5) rashes
6) serum sickness reactions
7) confusion
8) drowsiness
9) lethargy
10) seizures (high dose)
11) phlebitis
Drug interactions:
1) probenecid produces higher concentrations & longer 1//2life of penicillin
2) aminoglycosides are synergistic with penicillin
- should not be given in same IV solution or syringe due to drug inactivation
Laboratory:
- penicillin in specimen
- penicillin in serum/plasma
- penicillin in urine
Mechanism of action: inhibition of bacterial cell wall synthesis
Interactions
drug interactions
Related
penicillin binding protein
type B drug reaction; drug-induced hypersensitivity syndrome; drug rash with eosinophilia & systemic symptoms (DIHS, DRESS)
Specific
1st generation penicillin (natural)
2nd generation penicillin (penicillinase-resistant)
3rd generation penicillin (aminopenicillin)
4th generation penicillin (extended-spectrum)
penicillin V (Pen-Vee K, Veetids, V-Cillin K, Aoracillin-B, Beepen VK, Lanacillin VK, Ledercillin VK, Robicillin VK, Wincillin-VK)
temocillin (Temopen)
General
beta-lactam antibiotic
penicillanate
Database Correlations
Kegg map/map00311
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 31
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Deprecated Reference