GENTAMICIN is an antibiotic under the class of Aminoglycoside and it is an important drug for the treatment of many serious gram-negative bacillary infections and usually is the aminoglycoside of first choice because of its low cost and reliable activity against all but the most resistant gram-negative aerobes. Gentamicin is given parenterally, ophthalmically,and topically.
Availability of Gentamicin
Eye drops 0.3% w/v, cream 15g (0.1%w/w); INJECTION 2 ml ampoule (40 mg/ml),2 and 10 ml vials (40 mg/ml).
Dose of Gentamicin
Neonates-3 mg/kg every 12 hour.
Child- 2 weeks to 12 years; 2 mg/kg body weight 8 hly.
Therapeutic uses of Gentamicin
Gentamicin used for the therapy of proven or suspected serious gram-negative infections, especially those due to P. aeruginosa,Enterobacter, Klebsiella, Serratia, and other species resistant to less toxic antibiotics, including
The most important and serious side effects of gentamicin are nephrotoxicity and irreversible ototoxicity.
Pregnancy Category-C
Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Gentamicin under Schedule H drug; Warning-" To be sold by retail on the prescription of a Registered Medical practitioner only"
Availability of Gentamicin
Eye drops 0.3% w/v, cream 15g (0.1%w/w); INJECTION 2 ml ampoule (40 mg/ml),2 and 10 ml vials (40 mg/ml).
Dose of Gentamicin
- Intravenous infusion;Once daily dose regime; 5 to 7 mg/kg body weight, then adjust as per serum gentamicin concentration.
- Intramuscular or slow intravenous injection over at least 3 min.
Neonates-3 mg/kg every 12 hour.
Child- 2 weeks to 12 years; 2 mg/kg body weight 8 hly.
Therapeutic uses of Gentamicin
Gentamicin used for the therapy of proven or suspected serious gram-negative infections, especially those due to P. aeruginosa,Enterobacter, Klebsiella, Serratia, and other species resistant to less toxic antibiotics, including
- Urinary tract infections
- Bacteremia
- Infected burns
- Osteomyelitis;Inflammation of bone caused by infection, generally in the legs, arm or spine.
- Pneumonia
- Peritonitis;Inflammation of the membrane lining the abdominal wall and covering the abdominal organs.
- Otitis;An infection of the air-filled space behind the eardrum (the middle ear).
- Cholecystitis;Inflammation of the gallbladder, a small digestive organ beneath the liver.
- Septicaemia;A life-threatening complication of an infection.Blood poisoning, especially that caused by bacteria or their toxins.
- Acute pyelonephritis
- Prostatitis
- Skin infections
- Pelvic inflammatory disease
- Endocarditis;An infection of the heart's inner lining, usually involving the heart valves.
- Meningitis
- Listeriosis;Listeriosis is a serious infection usually caused by eating food contaminated with the bacterium Listeria monocytogenes.
- Tularaemia;It is a zoonosis - an infection which can be spread from animals to humans to cause an acute, febrile, granulomatous infection. It is caused by the bacterium Francisella tularensis which can infect many animals, especially small rodents, rabbits and hares.
- Brucellosis;An infection spread from animals to people, mostly by unpasteurised dairy products.
- Plague
- Surgical prophylaxis
- Ocular bacterial infection
- Cystic fibrosis;An inherited life-threatening disorder that damages the lungs and digestive system.
- Endometritis;It is an inflammatory condition of the lining of the uterus and is usually due to an infection.
- Gastroenteritis;An intestinal infection marked by diarrhoea, cramps, nausea, vomiting and fever.
- Granuloma inguinale;Granuloma inguinale is a bacterial disease caused by Klebsiella granulomatis characterized by genital ulcers.
Mechanism of action of Gentamicin
Gentamicin has the capacity to kill the bacteria by binding to 30S ribosomes and inhibit bacterial protein synthesis.The drug penetrate the bacterial cell membrane through pores.
Gentamicin have concentration-dependent bactericidal activity against Gram-negative aerobic bacteria ,anaerobic bacteria are universally resistant because aminoglycoside transport into cells is oxygen dependent.
Resistance to aminoglycosides may be by
- Aminoglycoside inactivating enzymes.
- Decreased binding of aminoglycosides to ribosomes.
- Decrease in permeability to the antibiotic.
Properties of Aminoglycosides
- Used as sulphate salt.
- Not absorbed orally.
- Penetration into CSF is very poor.
- Bactericidal in nature.
- Have narrow margin of safety.
- Ionized in solution.
- It is highly water soluble.
- Effective in aerobic gram negative infections.
- Exhibit synergic effect.
- Shows partial cross resistance.
- Excreted unchanged through kidneys.
The most important and serious side effects of gentamicin are nephrotoxicity and irreversible ototoxicity.
- Ototoxicity(Vestibular and auditory damage)
Ototoxicity is the most important toxicity.The ear has two functions -one is hearing and other is maintaining balance(vestibular apparatus).Both of these are affected by aminoglycosides.The drug get concentrated in the inner ear and damage the sensory cells.As the cochlear cells cannot regenerate ,there is permanent deafness.The auditory nerve degenerate.Elderly people are at a greater risk of developing deafness.Vestibular dysfunction results in headache,nausea,vomiting,dizziness,vertigo,nystagmus(Nystagmus is an involuntary, rapid and repetitive movement of the eyes) and difficulty in walking.Most symptoms subside in two weeks except ataxia(Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that includes gait abnormality) which may persist for 1-2 years.
- Nephrotoxicity
Amikacin attain high concentration in the kidneys and cause damage to the renal tubules These effect are reversible.The effect is more common in elderly patients.If there is impairment of renal function the dose interval must be increased;in severe renal impairment the dose should also be reduced.Serum concentration monitoring avoids both excessive and subtherapeutic concentration and can prevent toxicity and ensure efficacy.
- Neuromuscular blockade
It block neuromuscular transmission.
Other reactions are,
Other reactions are,
- Intrathecal or intraventricular administration may cause local inflammation and can result in radiculitis (radiculitis or radicular pain is transferred pain that “radiates” along the path of a nerve.) and other complications.
- Rarely, hypomagnesaemia
- On prolonged therapy; antibiotic-associated colitis, also nausea, vomiting, rash
- Bacterial/fungal corneal ulcers
- Ocular burning or irritation
- Thrombocytopenia,
- Joint pain.
- Transient elevation of serum bilirubin and aminotransferases.
It is clear to inform your doctor about your medical and drug history in detail before you receive any sort of prescription.Gentamicin should not be used if you have the following conditions:
- Myasthenia gravis(Myasthenia gravis (MG) is a long-term neuromuscular disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing)
- Hypersensitivity.
- Pregnancy .
- Hepatic impairment.
- Perforated ear drum.
Special precautions
- Do not mix with any other drug in the same syringe.
- Avoid use of other ototoxic drugs .
- Avoid use of other nephrotoxic drugs .
- Avoid use of drugs having muscle relaxant action .
- Parkinsonism.
- Pregnancy.
- Lactation.
- Renal impairment.
- Significant obesity.
- Postoperative or other conditions that depress neuromuscular transmission.
- Neonates.
- Infants.
- Elderly.
- Monitor renal functions before and during treatment,especially patient with renal dysfunction.
Interactions Of Gentamicin
- Synergistic with ampicillin,benzylpenicillin and other beta-lactam antibiotics.
- Increased risk of severe respiratory depression when used concurrently with anaesthetics or opioids.
- May reduce renal clearance of zalcitabine.
- Induce hypocalcaemia when used with bisphosphonates.
- Increased ototoxicity when combined with ethacrynic acid and furosemide.
- Cephalosporins,cyclosporine,cisplatin,vancomycin,hydrocortisone and indomethacin potentiate nephrotoxicity.
Parameters to Monitor in case of Gentamicin administration.
- Renal function tests before and q 2–3 days during therapy.
- Audiometry and electronystagmography may be performed in patients able to cooperate.
- Monitor aminoglycoside serum concentrations carefully, especially in the elderly, those with renal impairment, hemodynamically unstable patients,and those requiring high peak serum concentrations or prolonged (>10 days) therapy.
- In adults receiving conventional therapy, monitor serum levels after steady state is achieved. With once-daily therapy targeting high peaks and undetectable troughs, obtain levels after the first dose. Obtain follow-up levels if renal function changes.
- In neonates or other patients with rapidly changing renal function, obtain serum drug concentrations initially and q 2–3 days until stable. However,with once- or twice-daily dosage and in pediatric patients, trough serum levels are often undetectable and other sampling strategies are necessary.
Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Gentamicin under Schedule H drug; Warning-" To be sold by retail on the prescription of a Registered Medical practitioner only"
0 comments:
Post a Comment