Rocygen

Each mL contains: Gentamicin (as sulfate) equivalent to Gentamicin 40 mg.
Gentamicin sulfate, a water-soluble antibiotic of the aminoglycoside group, is derived from Micromonospora purpurea, an actinomycete. It is a sterile, nonpyrogenic, aqueous solution for parenteral administration and is available both with and without preservatives.

Pharmacotherapeutic group: Antibacterials for systemic use.
Pharmacology: Pharmacodynamics: Gentamicin is a mixture of antibiotic substances produced by the growth of Micromonospora purpurea. It is bactericidal with greater antibacterial activity than streptomycin, neomycin or kanamycin.
Gentamicin exerts a number of effects on cells of susceptible bacteria. It affects the integrity of the plasma membrane and the metabolism of RNA, but its most important effects is inhibition of protein synthesis at the level of the 30s ribosomal subunit.
Pharmacokinetics: Gentamicin is not readily absorbed from the gastro-intestinal tract. Gentamicin is 70-85% bound to plasma albumin following administration and is excreted 90% unchanged in urine.
The half-life for its elimination in normal patients is 2 to 3 hours.
Effective plasma concentration is 4-8 μg/ml.
The volume of distribution (vd) is 0.3 l/kg.
The elimination rate constant is: 0.02 hr-1 for anuric patients*; 0.30 hr-1 normal.
*Therefore in those with anuria care must be exercised following the usual initial dose, any subsequent administration being reduced in-line with plasma concentrations of gentamicin.

Gentamicin is a bactericidal antibiotic which acts by inhibiting protein synthesis in susceptible bacteria.
Indications for the use of Gentamicin Injection are bacteremia, septicemia, urinary tract infections, severe chest infections, and other systemic infections due to susceptible bacteria.

Gentamicin Injection is normally administered intramuscularly, but may be given intravenously if required. If intravenous administration is necessary the normal intramuscular dose should be given as a bolus injection into the tubing of the giving set or directly into the venous system over a period of two to three minutes.
Gentamicin Injection should not be given as slow infusion or mixed with other drugs before use (see Incompatibilities under Cautions for Usage). With either intramuscular or intravenous administration the following dosage applies for normal renal function: Adults: 3-4 mg/kg bodyweight daily in divided doses.
Typical doses: 60 kg and over: 80 mg eight-hourly.
Less than 60 kg: 60 mg eight-hourly.
In cases of impaired renal function a reduction in dosage frequency is recommended. The following table is a guide to recommended dosage schedule: See table.

Click on icon to see table/diagram/image

Urinary tract infections: Alternatively, if renal function is not impaired, 160 mg once daily may be used.
In life-threatening infections the frequency of dosage may need to be increased to six-hourly and the quantity of each dose may also be increased at the discretion of the clinician up to a total dosage of 5 mg/kg in 24 hours. In such cases it is advisable to monitor gentamicin serum levels.
Use in the elderly: Adjust dosage according to weight and renal function. Periodic serum monitoring is desirable.
Children: In children and in neonates, it can be expected that serum levels will be lower than those found in adults at equivalent dosage per body weight.
The recommended pediatric dosage is therefore as follows: Up to 12 years: 6 mg/kg in 24 hours in 3 equally divided doses (i.e. 2 mg/kg eight-hourly).
In infants up to two weeks this dosage should be given in 2 equally divided doses (i.e. 3 mg/kg 12-hourly). Serum levels should preferably be monitored daily.
In neonates, infants and children, subsequent dosage will often need to be increased to achieve therapeutic serum levels. Peak levels should be measured about one hour after intramuscular or intravenous injection and should reach 4 mcg/mL, but not exceed 10 mcg/mL.

Symptoms: Dizziness, vertigo and hearing loss if overdose accidentally given parenterally.
Treatment: If the reaction is severe consider hemodialysis.

There are no absolute contraindications other than sensitivity to one of the ingredients, allergy to gentamicin and myasthenia gravis.
Use in Pregnancy: Although there is no animal evidence of teratogenicity, gentamicin crosses the placenta and there is a risk of ototoxicity in the fetus and gentamicin should only be used where the seriousness of the mother's condition justifies the risk.

Where renal function is impaired through disease or old age, the frequency, but not the amount of each dose should be reduced according to the degree of impairment. Gentamicin is excreted by simple glomerular filtration, and dosage frequency may be predicted by assessing creatinine clearance rates or blood urea and reducing the frequency accordingly.
It is also advisable to check serum levels to confirm that peak (one hour) levels do not exceed 10 mcg/mL and that trough levels (before next injection) do not exceed 2 mcg/mL.

There are no proven cases of intrauterine damage caused by gentamicin. However, in common with most drugs known to cross the placenta, usage in pregnancy should only be considered in life threatening situations where expected benefits outweigh possible risks. In the absence of gastro-intestinal inflammation, the amount of gentamicin ingested from the milk is unlikely to result in significant blood levels in breast-fed infants.

As with all aminoglycosides, at critical levels gentamicin exhibits toxicity. Nephrotoxicity may occur, resulting in a gradual reduction in creatinine clearance after about two weeks of treatment. This is rapidly reversed if the drug is withdrawn. Most cases have pre-existing renal disease or have received other nephrotoxic agents. With gentamicin the vestibular mechanism may be affected when serum levels of 10 mcg/mL or when a trough level of 2 mcg/mL are exceeded. This is usually reversible if observed promptly and the dose adjusted. In the patient with normal renal function it is virtually impossible to achieve these levels at standard dosage.

The potential nephrotoxicity of cephalosporins may be increased in the presence of gentamicin and monitoring of kidney function is therefore recommended with this combination.
Furosemide and piretanide may potentiate the ototoxicity of gentamicin, and ethacrynic acid, which is ototoxic in its own right, should be avoided with gentamicin.
Ticarcillin has been shown to reduce the gentamicin activity in vivo and, if clinically indicated, should be given at different times from gentamicin.
Neuromuscular blockade and respiratory paralysis have occasionally been reported from administration of aminoglycosides to patients who have received curare-type muscle relaxants during anesthesia.
Bacteriostatic antibiotics may give an antagonistic interaction, but in some cases (e.g. with clindamycin and lincomycin) the disadvantage of antagonism may be outweighed by the addition of activity against anaerobic organisms.

Incompatibilities: In general, mixing Gentamicin Injection with other drugs prior to administration is not in particular advised. The following are incompatible in mixed solution with Gentamicin Injection: penicillins, cephalosporins, erythromycin, lipiphysan, heparins and sodium bicarbonate. In the latter case carbon dioxide may be liberated on addition of the two solutions. Normally this will dissolve in the solution, but under some circumstances small bubbles may form.
Dilution in the body will obviate the danger of physical and chemical incompatibility and enable Gentamicin Injection to be given concurrently with the drugs listed previously either as a bolus injection into the drip tubing, with adequate flushing, or at separate sites. However, in the case of carbenicillin and gentamicin they should only be given at separate sites.

Store at temperatures not exceeding 25°C; Protect from light.

Aminoglycosides

J01GB03 - gentamicin ; Belongs to the class of other aminoglycosides. Used in the systemic treatment of infections.

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