GENTAMICIN (CIDOMYCIN, GARAMYCIN)

GENTAMICIN (CIDOMYCIN, GARAMYCIN)

CLASSIFICATION

� Aminoglycoside antibiotic

MODE OF ACTION

Is a bactericidal and acts by inhibiting protein synthesis in susceptible bacteria. Cell death results

INDICATIONS

For the treatment of infections due to one or more strains of bacteria including Psuedomonias Aeruginosa, Gonorrhoea, Escherichia coli, Klebsiella, Enterobactera and Serratia species, also Citrobacter species and Staphylococcus

 � Respiratory tract infections.

� Urinary tract infections.

� Infected wounds - bone and soft tissue.

 � Septic abortion and burns complicated by sepsis.

� In suspected gram negative sepsis.

PHARMOCOLOGY

Rapidly absorbed after intramuscular injection and peak serum levels are usually achieved within 30 - 90 minutes and are measurable for 6 - 8 hours. Gentamicin is excreted almost entirely by the renal glomerular filtration. The serum half life of Gentamicin in an adult with normal renal function is 2 - 3 hours. It is prolonged with patients who have renal impairment.

CONTRA INDICATIONS

� Patients with known hypersensitivity

ADVERSE REACTIONS

� Otoxcicity and nephrotoxicity.

� Purpura.

 � Increased serum transaminases.

� Increased serum bilirubin.

� Nausea.

� Vomiting.

� Headache.

PRESENTATION

80 mg Gentamicin BP in 2 ml. DOSAGE AND ADMINISTRATION IM INJECTION Suitable SC INJECTION Not recommended IV INJECTION Suitable

Administer slowly over 3 - 5 minutes for a dose less than 200 mg. As a bolus into the side arm of a giving set or directly into the vein. IV INFUSION For a dose greater than 200 mg can be administered as an infusion over 20 - 120 minutes.

STABILITY

Undiluted solution protect from light. Multi dose vials may be kept for 24 hours under refrigeration once pierced. The recommended maximal initial single dose is 640 mg This dose should be calculated according to lean body weight as aminoglycoside distribute minimally to adipose tissue.

PAEDIATRIC

3 mg/kg - 7 mg/kg according to condition and prescription details.

COMPATIABLE FLUIDS

Glucose 4 % Glucose 5 % glucose 10 % Hartmans Ringers Sodium Chloride 9 %

COMPATIABLE DRUGS

Aminophylline Aztreonam Cefoxitin Cefuroxime (for 1 hour) Cimetidine Ciprofloxacin Clindamysin phosphate Dopamine (potency retained for 6 hours) Famotidine (compatible for four hours at 22 degree in D5W 5 %) Fluconazole Metronidazole Morphine (compatible for 1 hour) Penicillin G Pethidine (compatible for 1 hour) Verapmil Zantac

COMPATIABLE VIA THE Y SITE

Acyclovir Amiodarone Andansetron Ciprofloxin Cyslosporan Esmolol Famotidine Fucanozole Facarnet Insulin Labetalol Magnesium Morphine pethidine Tolazoline Zidovudine

COMPATIABLE IN SYRINGE

Lignocaine Lignocaine with Adrenaline Penicillin Tobramycin

INCOMPATIABLE DRUGS

Amphotericin Ampicillin Cephazolin Cefrazidime Cefuroxime Cephalothin Cephamandole Fat emulsion 10 % Fruesimide Heparin Hydrocortisone Sodium bicarb Ticarcillin Cephamandole

SUMMARY OF ONCE DAILY GENTAMICIN THERAPY MONITORING (As Per Joy Gailer Manager Of The Pharmacy Services Page 639)

The first blood sample is collected 30 minutes after completion of the infusion or bolus - Sample taken from the opposite arm.

The second sample is collected 6 - 8 hours after the commencement of the infusion or bolus.

It is imperative that the time of administration (start and stop times of the infusion or time of bolus) and the times of blood sampling are recorded on the Gentamycin monitoring form as accurately as possible.

Monitoring of blood levels is necessary if therapy is to continue for > 48 hours. To be monitored every second day.

Ideally, levels should be take after the first dose to allow dosage prediction by the pharmacy department.

MULTIPLE DAILY DOSING

Is still advised in the treatment of infective endocartistis, cystic fibrosis, management of neonatal infections and the gram negative infections in pregnancy.

Monitoring needs to be more frequently than for single daily dosing, commencing 24 hours after the first dose and repeated 2 - 3 times a week, depending on renal function.

SAMPLE taken from the opposite arm just before the first dose on the second day and 15 minutes after the completion of the injection.

TROUGH LEVELS

Should be < 1.5 mg/L Peak level should be > 5 mg/L for non pulmonary infection and > 8 mg/L for pulmonary infection

Toxicity is related to trough levels which in turn are related to renal function and duration of therapy. Hence despite blood levels nephrotoxicity are more likely if therapy extends beyond 10 to 14 days.