About: Penicillins
Always check the BNF or equivalent for prescribing advice.
- Penicillins were the first antibiotics, discovered by Alexander Fleming in 1928. Fleming noticed the antibacterial properties of penicillin when he observed that the mould Penicillium notatum inhibited growth in a contaminated culture of Staphylococcus aureus.
- Recognizing the potential, he isolated the compound and named it penicillin, publishing his findings and its applications in medicine.
Action
- Bactericidal antibiotics that inhibit cell wall synthesis.
- Prevent formation of peptidoglycan cross-bridges in the bacterial cell wall.
- Contain a beta-lactam ring, which is vulnerable to bacterial beta-lactamase enzymes.
Notes
- Clavulanic acid can inhibit beta-lactamase, preserving the effectiveness of penicillins against beta-lactamase-producing bacteria.
Indications
- Refer to the BNF for specific prescribing indications.
Interactions
- Ampicillin may reduce the efficacy of oral contraceptives (OCP).
Cautions
- Consult the BNF for detailed cautionary advice.
Excretion
- Penicillins undergo enterohepatic circulation and are reabsorbed.
- Primarily renally excreted via active tubular secretion.
- Probenecid can inhibit renal excretion, effectively doubling blood levels of penicillin.
Contraindications
- Refer to the BNF for contraindications.
Side Effects
- Acute anaphylaxis is rare, occurring in approximately 5 per 10,000 patients.
- Other reactions include rashes, hemolytic anemia, and interstitial nephritis.
- Approximately 10% cross-sensitivity with cephalosporins.
- Risk of convulsions with high intrathecal or intravenous doses.
- Characteristic ampicillin rash in patients with Epstein-Barr Virus (EBV) or chronic lymphocytic leukemia