DOSES OF PENICILLINS:
Most commonly used penicillins have the following doses:
* BENZYL PENICILLIN:
By intramuscular or slow intravenous injection or by infusion:
2.4-4.8 g daily in divided doses
* PHENOXYMETHYL PENICILLIN:
By oral route:
500 mg every 6 hours up to 1g every 6 hours in severe infections.
* AMOXICILLIN:
By mouth:
250mg every 8 hours, doubled in severe infections.
* AMPICILLIN:
By mouth:
0.25g-1g every 6 hours, at least 30 minutes before food.
DRUG INTERACTIONS OF PENICILLINS:
* ALLOPURINOL:
Increased risk of rash when amoxicillin and ampicillin are given with allopurinol.
* ANTIBACTERIALS:
Absorption of phenoxy methyl penicillin is reduced by neomycin.
* CYTOTOXICS:
Penicillins reduce excretion of methotrexate (increased risk of toxicity).
* MUSCLE RELAXANTS:
Piperacillin enhances effects of non depolarising muscle relaxants and suxamethonium.
* PROBENECID:
Excretion of penicillins is reduced by probenecid.
* SULFINPYRAZONE:
Excretion of penicillins is reduced by sulfinpyrazone.
