Benzylpenicillin

Parenteral
Susceptible infections
Adult: 0.6-3.6 g daily in 4-6 divided doses, via IM, slow IV inj or infusion. Higher doses may be needed in more serious infections. IV doses >1.2 g should be given at a rate of not more than 300 mg/min.
Child: Newborn infants: 50 mg/kg daily in 2 divided doses; 1-4 wk 75 mg/kg daily in 3 divided doses; >1 mth to 12 yr 100 mg/kg daily in 4 divided doses, not exceeding 4 g/day.
Renal impairment: Dosing interval should be no more frequent than every 8-10 hr.
Reconstitution: Loosen the powd, then, hold the vial horizontally and rotate it while slowly directing the stream of diluent against the wall of the vial. Shake the vial vigorously after all the diluent has been added. Depending on the route of admin, reconstitute w/ sterile water for inj, NaCl 0.9% inj or dextrose 5% inj.
Incompatibility: Amphotericin B, cimetidine, cytarabine, flucloxacillin, hydroxyzine, methylprednisolone, promethazine, metoclopramide and soln containing metal ions.

Intravenous
Bacterial endocarditis
Adult: 7.2-12 g or more, given daily in divided doses.
Renal impairment: Dosing interval should be no more frequent than every 8-10 hr.
Reconstitution: Loosen the powd, then, hold the vial horizontally and rotate it while slowly directing the stream of diluent against the wall of the vial. Shake the vial vigorously after all the diluent has been added. Depending on the route of admin, reconstitute w/ sterile water for inj, NaCl 0.9% inj or dextrose 5% inj.
Incompatibility: Amphotericin B, cimetidine, cytarabine, flucloxacillin, hydroxyzine, methylprednisolone, promethazine, metoclopramide and soln containing metal ions.

Intravenous
Intrapartum prophylaxis against group B Streptoccocal infection in neonates
Adult: Initially, 3 g, then 1.5 g 4 hrly until delivery.
Renal impairment: Dosing interval should be no more frequent than every 8-10 hr.
Reconstitution: Loosen the powd, then, hold the vial horizontally and rotate it while slowly directing the stream of diluent against the wall of the vial. Shake the vial vigorously after all the diluent has been added. Depending on the route of admin, reconstitute w/ sterile water for inj, NaCl 0.9% inj or dextrose 5% inj.
Incompatibility: Amphotericin B, cimetidine, cytarabine, flucloxacillin, hydroxyzine, methylprednisolone, promethazine, metoclopramide and soln containing metal ions.

Intravenous
Meningococcal meningitis
Adult: 2.4 g 4 hrly. Max: 18 g/day in meningococcal meningitis. Doses >1.2 g should be given at a rate not more than 300 mg/min.
Child: Newborn infants: 100 mg/kg daily in 2 divided doses; 1-4 wk 150 mg/kg daily in 3 divided doses; >1 mth to 12 yr 180-300 mg/kg daily in 4-6 divided doses.
Renal impairment: Dosing interval should be no more frequent than every 8-10 hr.
Reconstitution: Loosen the powd, then, hold the vial horizontally and rotate it while slowly directing the stream of diluent against the wall of the vial. Shake the vial vigorously after all the diluent has been added. Depending on the route of admin, reconstitute w/ sterile water for inj, NaCl 0.9% inj or dextrose 5% inj.
Incompatibility: Amphotericin B, cimetidine, cytarabine, flucloxacillin, hydroxyzine, methylprednisolone, promethazine, metoclopramide and soln containing metal ions.

Intravenous
Pneumococcal meningitis
Adult: 2.4 g 4 hrly. Max: 18 g/day in meningococcal meningitis. Doses >1.2 g should be given at a rate not more than 300 mg/min.
Child: Newborn infants: 100 mg/kg daily in 2 divided doses; 1-4 wk 150 mg/kg daily in 3 divided doses; >1 mth to 12 yr 180-300 mg/kg daily in 4-6 divided doses.
Renal impairment: Dosing interval should be no more frequent than every 8-10 hr.
Reconstitution: Loosen the powd, then, hold the vial horizontally and rotate it while slowly directing the stream of diluent against the wall of the vial. Shake the vial vigorously after all the diluent has been added. Depending on the route of admin, reconstitute w/ sterile water for inj, NaCl 0.9% inj or dextrose 5% inj.
Incompatibility: Amphotericin B, cimetidine, cytarabine, flucloxacillin, hydroxyzine, methylprednisolone, promethazine, metoclopramide and soln containing metal ions.

Should be taken on an empty stomach. Take w/ a full glass of water on an empty stomach 1 hr before or 2 hr after meals. Do not take acidic beverages w/in 1 hr of a dose.

Hypersensitivity to benzylpenicillin and other penicillins.

Patients w/ history of allergy esp β-lactam allergy and/or asthma, seizure disorder. Diabetic patients. Renal impairment. Pregnancy and lactation. Monitoring Parameters Monitor electrolyte, hepatic, renal, cardiac and haematologic function; signs and symptoms of anaphylaxis during 1st dose.

Nausea, vomiting, stomatitis, black or hairy tongue, rash, fever, serum-like sickness, convulsions, interstitial nephritis, haemolytic anaemia, granulocytopenia, agranulocytosis, leucopenia, thrombocytopenia.
Potentially Fatal: Anaphylaxis, pseudomembranous colitis.

Symptoms: Agitation, confusion, asterixis, hallucinations, stupor, coma, multifocal myoclonus, seizures and encephalopathy, hyperkalaemia. Management: Symptomatic and supportive treatment.

May reduce the efficacy of OC. May increase the risk of methotrexate toxicity. Increased plasma concentration w/ probenecid. Antagonism of bactericidal effect w/ bacteriostatic antibacterials (e.g. erythromycin, tetracyclines).

Food may reduce the absorption of benzylpenicillin.

May interfere w/ urinary glucose tests, Coombs test, and test for urinary or serum proteins. May interfere w/ diagnostic tests which use bacteria (e.g. Guthrie test).

Benzylpenicillin has a bactericidal action against gm+ve bacteria, gm-ve cocci, some other gm-ve bacteria, spirochetes and actinomycetes. It inhibits final cross-linking stage of peptidoglycan production through binding and inactivation of transpeptidases on the inner surface of the bacterial cell membrane, thus inhibiting bacterial cell wall synthesis. It is inhibited by penicillinase and other β-lactamases.
Absorption: Rapidly appears in blood after IM inj. Inactivated fairly rapidly by gastric acid and up to approx 30% is absorbed. Absorption is reduced by the presence of food. Time to peak plasma concentration: 15-30 min (IM); approx 1 hr (oral/IV).
Distribution: Widely distributed. Crosses the placenta and enters breast milk (small amounts). Volume of distribution: 0.53-0.67 L/kg. Plasma protein binding: Approx 60%.
Metabolism: Undergoes limited hepatic metabolism to penicilloic acid.
Excretion: Via urine (58-85% as unchanged drug) and bile (small amounts). Plasma half-life: Approx 30 min.

Intravenous: Store between 20-25°C. Reconstituted soln: Store between 2-8°C. Parenteral: Store between 20-25°C. Reconstituted soln: Store between 2-8°C.

Penicillins

S01AA14 - benzylpenicillin ; Belongs to the class of antibiotics. Used in the treatment of eye infections.
J01CE01 - benzylpenicillin ; Belongs to the class of beta-lactamase sensitive penicillins. Used in the systemic treatment of infections.