Megacillin - General Information
A penicillin derivative commonly used in the form of its sodium or potassium salts in the treatment of a variety of infections. It is effective against most gram-positive bacteria and against gram-negative cocci. It has also been used as an experimental convulsant because of its actions on gamma-aminobutyric acid mediated synaptic transmission. [PubChem]
Pharmacology of Megacillin
Megacillin is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. The name "penicillin" can either refer to several variants of penicillin available, or to the group of antibiotics derived from the penicillins. Megacillin has in vitro activity against gram-positive and gram-negative aerobic and anaerobic bacteria. The bactericidal activity of penicillin G results from the inhibition of cell wall synthesis and is mediated through penicillin G binding to penicillin binding proteins (PBPs). Megacillin is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases.
Megacillin for patients
Concurrent administration of bacteriostatic antibiotics (e.g., erythromycin, tetracycline) may diminish the bactericidal effects of penicillins by slowing the rate of bacterial growth. Bactericidal agents work most effectively against the immature cell wall of rapidly proliferating microorganisms. This has been demonstrated in vitro; however, the clinical significance of this interaction is not well documented. There are few clinical situations in which the concurrent use of ''static'' and ''cidal '' antibiotics are indicated. However, in selected circumstances in which such therapy is appropriate, using adequate doses of antibacterial agents and beginning penicillin therapy first, should minimize the potential for interaction.
Penicillin blood levels may be prolonged by concurrent administration of probenecid which blocks the renal tubular secretion of penicillins.
Displacement of penicillin from plasma protein binding sites will elevate the level of free penicillin in the serum.
A history of a previous hypersensitivity reaction to any penicillin is a contraindication.
Additional information about Megacillin
Megacillin Indication: For use in the treatment of severe infections caused by penicillin G-susceptible microorganisms when rapid and high penicillin levels are required.
Mechanism Of Action: By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, penicillin G inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that penicillin G interferes with an autolysin inhibitor.
Drug Interactions: Methotrexate The penicillin increases the effect and toxicity of methotrexate
Anisindione The IV penicillin increases the anticoagulant effect
Dicumarol The IV penicillin increases the anticoagulant effect
Acenocoumarol The IV penicillin increases the anticoagulant effect
Warfarin The IV penicillin increases the anticoagulant effect
Ethinyl Estradiol This anti-infectious agent could decreases the effect of the oral contraceptive
Mestranol This anti-infectious agent could decreases the effect of the oral contraceptive
Doxycycline Possible antagonism of action
Demeclocycline Possible antagonism of action
Tetracycline Possible antagonism of action
Rolitetracycline Possible antagonism of action
Oxytetracycline Possible antagonism of action
Minocycline Possible antagonism of action
Methacycline Possible antagonism of action
Food Interactions: Not Available
Generic Name: Penicillin G
Synonyms: Not Available
Drug Category: Anti-Bacterial Agents; Penicillins
Drug Type: Small Molecule; Approved
Absorption: Rapidly absorbed following both intramuscular and subcutaneous injection. Initial blood levels following parenteral administration are high but transient.
Toxicity (Overdose): Oral LD50 in rat is 8900 mk/kg. Neurological adverse reactions, including convulsions, may occur with the attainment of high CSF levels of beta-lactams.
Protein Binding: Bind to serum proteins, mainly albumin.
Biotransformation: Not Available
Half Life: Not Available
Dosage Forms of Megacillin: Powder, for solution Intramuscular
Powder, for solution Oral
Powder, for solution Intravenous
Chemical IUPAC Name: (2S,5R,6R)-3,3-dimethyl-7-oxo-6-[(2-phenylacetyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Chemical Formula: C16H18N2O4S
Penicillin G on Wikipedia: Not Available
Organisms Affected: Enteric bacteria and other eubacteria