Benzylpenicillin / Penicillin G

ADMINISTRATION ROUTES:

IV

ALTERNATIVE NAMES:

Penicillin G, BenPen

ICU INDICATIONS:

1. Treatment of infections caused by susceptible organisms

PRESENTATION AND ADMINISTRATION:

IV:

ICU stocks 600 mg (=1 mega unit) vials of Pencillin G Sodium (Novartis)

Add 1.6 mL of water for injection to each 600 mg vial (using 1.6 mL of water for injection in a vial will give a concentration of 300 mg/mL)

Store at room temperature. Protect from light

Benzylpenicillin is not stable in glucose and glucose/saline combination IV fluids. Compatible with water for injection, Normal saline

Administer by either IV injection or intermittent infusion

To administer by IV injection dilute to 10 mL with water for injection and inject slowly at a rate not greater than 300 mg/min

To administer by intermittent infusion add to 50-100 mL of compatible IV fluid and infuse over 30-60 minutes

The dry powder is relatively stable and may be stored at room temperature without significant loss of potency. Sterile solutions may be kept in the refrigerator one week without significant loss of potency. Solutions prepared for intravenous infusion are stable at room temperature for at least 24 hours

DOSAGE:

IV:

In ICU patients higher dose penicillin is usually preferred

1.2 gm-2.4 gm q4-6hrly

For bacterial meningitis use 2.4 gm q4hrly.

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose in renal impairment

Dose in renal replacement therapy

DOSAGE IN PAEDIATRICS:

30-50 mg/kg q6hrly

Note: reduced dosage may be required in neonates

CLINICAL PHARMACOLOGY:

Penicillin G is bactericidal against penicillin-susceptible microorganisms during the stage of active multiplication. It acts by inhibiting biosynthesis of cell-wall mucopeptide. It is not active against the penicillinase-producing bacteria, which include many strains of staphylococci.

Penicillin G is highly active in vitro against:

• Staphylococci (except penicillinase-producing strains)

• Streptococci (groups A, C, G, H, L, and M)

• Pneumococci

Other organisms susceptible in vitro to penicillin G are:

• Neisseria gonorrhoea

• Corynebacterium diphtheriae

• Bacillus anthracis

• Clostridia

• Actinomyces bovis

• Streptobacillus moniliformis

• Listeria monocytogenes

• Leptospira

• Treponema pallidum (extremely susceptible)

Some species of gram-negative bacilli are susceptible to moderate to high concentrations of penicillin G obtained with intravenous administration. These include:

• Most strains of Escherichia coli

• All strains of Proteus mirabilis, Salmonella, and Shigella

• Some strains of Enterobacter aerogenes

• Alcaligenes faecalis

CONTRAINDICATIONS:

1. Hypersensitivity to any penicillin

WARNINGS:

Anaphylaxis

Serious and occasional fatal hypersensitivity (anaphylactoid) reactions have been reported in patients on penicillin therapy.

Pseudomembranous colitis

Pseudomembranous colitis has been reported with nearly all antibacterial agents, including penicillin, and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhoea subsequent to the administration of antibacterial agents.

PRECAUTIONS:

General:

Penicillin should be used with caution in individuals with histories of significant allergies and/or asthma.

Haemolytic anaemia, leukopaenia, thrombocytopaenia, neuropathy, and nephropathy are rarely observed adverse reactions and are usually associated with high intravenous dosage

High dosage of penicillin G sodium may result in congestive heart failure due to high sodium intake

Laboratory Tests:

No tests in addition to routine ICU tests are required

IMPORTANT DRUG INTERACTIONS IN ICU:

Fusidic Acid: May diminish the therapeutic effect of Penicillins.

Methotrexate: Penicillins may decrease the excretion of Methotrexate

Mycophenolate: Penicillins may decrease serum concentrations of the active metabolite(s) of Mycophenolate. This effect appears to be the result of impaired enterohepatic recirculation

Tetracycline Derivatives: May diminish the therapeutic effect of Penicillins

ADVERSE REACTIONS:

Body as a Whole:

Anaphylaxis, serum sickness

Nervous System:

Coma (high doses), hyperreflexia (high doses), seizures (high doses)

Digestive System:

Pseudomembranous colitis, hepatitis

Haematological system:

Neutropaenia, haemolytic anaemia (rare, high doses)

Metabolic:

Hypernatraemia

Renal System:

Acute interstitial nephritis (high doses), renal tubular damage (high doses)

Skin:

Rash