WHO Model Prescribing Information: Drugs used in Bacterial Infections
(2001; 179 pages) View the PDF document
Table of Contents
View the documentPreface
View the documentIntroduction
Open this folder and view contentsUpper respiratory tract infections
Open this folder and view contentsLower respiratory tract infections
Open this folder and view contentsOther respiratory tract infections
Open this folder and view contentsPerioral and dental infections
Open this folder and view contentsGastrointestinal tract infections
Open this folder and view contentsUrinary tract infections
Open this folder and view contentsSkin and soft tissue infections
Open this folder and view contentsBone and joint infections
Open this folder and view contentsSexually transmitted diseases
Open this folder and view contentsCardiovascular infections
Open this folder and view contentsCentral nervous system infections
Open this folder and view contentsMiscellaneous infections
Open this folder and view contentsSepticaemia
Close this folderDrugs (for details of contraindications, etc., see individual drug entries)
View the documentAmoxicillin
View the documentAmoxicillin + clavulanic acid
View the documentAmpicillin
View the documentBenzylpenicillin
View the documentBenzathine benzylpenicillin
View the documentProcaine benzylpenicillin
View the documentCefalexin
View the documentCefazolin
View the documentCefotaxime
View the documentCeftazidime
View the documentCeftriaxone
View the documentCefuroxime
View the documentChloramphenicol
View the documentCiprofloxacin
View the documentClindamycin
View the documentCloxacillin1
View the documentDoxycycline
View the documentErythromycin
View the documentGentamicin
View the documentImipenem + cilastatin
View the documentMetronidazole
View the documentNalidixic acid
View the documentNitrofurantoin
View the documentNystatin
View the documentPhenoxymethylpenicillin
View the documentRifampicin
View the documentSpectinomycin
View the documentStreptomycin
View the documentSulfadiazine
View the documentSulfamethoxazole + trimethoprim
View the documentTetracycline
View the documentTinidazole
View the documentTrimethoprim
View the documentVancomycin
 

Gentamicin

Injection, 10mg, 40mg (as sulfate)/ml in 2-ml vial

General information

Gentamicin is a broad-spectrum aminoglycoside produced by Micromonospora purpurea. It is bactericidal against many aerobic Gram-negative bacteria but has little activity against most Gram-positive organisms with the exception of staphylococci.

Gentamicin is poorly absorbed from the gastrointestinal tract. After parenteral administration, it is widely distributed in the body tissues and fluids. Its penetration into the cerebrospinal fluid is poor. Its plasma half-life is 2 - 4 hours and it is excreted unchanged in the urine. A small fraction is tightly bound intracellularly and accumulates in the body tissues. It readily crosses the placenta and is distributed in breast milk.

Clinical information

Uses

Treatment of:

• pneumonia in adults and children > 5 years, together with benzylpenicillin

• atypical pneumonia in adults and children > 5 years, together with benzylpenicillin and erythromycin

• nosocomial pneumonia, together with cloxacillin or ceftazidime

• pneumonia due to Staphylococcus aureus in children aged from 2 months to 5 years, together with cloxacillin

• neonatal pneumonia, together with amoxicillin

• acute cholecystitis and acute pyelonephritis, together with ampicillin

• acute peritonitis, together with ampicillin and metronidazole

• gangrene, together with metronidazole and either benzylpenicillin or clindamycin

• contaminated soft tissue injuries, together with metronidazole and cloxacillin

• very severe pelvic inflammatory disease in adults (hospitalized patients), together with clindamycin and doxycycline

• infective endocarditis (initial empirical therapy), together with benzylpenicillin and cloxacillin

• infective endocarditis (initial empirical therapy) in patients allergic to penicillins or with nosocomial infections, and prosthetic valve endocarditis, together with vancomycin

• endocarditis due to α-haemolytic streptococci, together with benzylpenicillin or ampicillin

• endocarditis due to enterococci, together with benzylpenicillin or ampicillin

• endocarditis due to meticillinsusceptible Staphylococcus aureus, together with cloxacillin

• culture-negative endocarditis, together with benzylpenicillin

• neonatal meningitis due to unknown pathogen and neonatal meningitis due to Listeria monocytogenes, together with ampicillin

• neonatal meningitis due to group B streptococci, together with benzylpenicillin

• brucellosis, together with doxycycline or sulfamethoxazole + trimethoprim

• tularaemia and plague

• septicaemia (initial empirical therapy) in adults and children > 5 years, together with cloxacillin or cefazolin or clindamycin or chloramphenicol

• neonatal septicaemia (initial empirical therapy), together with ampicillin.


Prophylaxis in contaminated surgery, together with clindamycin.

Dosage and administration

The dosages should be reduced in patients with renal impairment.

When gentamicin is used in combination with a β-lactam antimicrobial in the treatment of endocarditis, it should be administered every 8 hours. Basal plasma levels of gentamicin should not exceed 1 mg/l. The maximum period of gentamicin therapy without monitoring plasma levels should be 72 hours. If vancomycin is used, peak plasma levels of 30 - 40mg/l and basal plasma levels of 5 - 15 mg/l are recommended. These levels are specific for the management of endocarditis and do not apply to other circumstances.

Pneumonia in adults and children >5 years

Hospitalized patients

Adults: 5 - 7mg/kg i.v. daily in divided doses, together with benzylpenicillin 2 million IU i.v. or i.m. every 4 - 6 hours for 7 days.

Children > 5 years: 7.5mg/kg i.v. in 1 - 3 divided doses daily, together with benzylpenicillin 50 000 - 100 000 IU/kg (maximum 2 million IU) i.v. or i.m. every 4 - 6 hours for 7 days.

Patients with atypical pneumonia should also receive erythromycin 1g (children: 10mg/kg; maximum 1g) i.v. every 6 hours for 14 days.

Pneumonia due to Staphylococcus aureus in children aged from 2 months to 5 years

7.5mg/kg i.v. in 1 - 3 divided doses daily, together with cloxacillin 25 - 50mg/kg (maximum 2g) orally every 6 hours for at least 3 weeks.

Neonatal pneumonia

2.5mg/kg i.v. every 8 hours (neonates <7 days: 2.5mg/kg i.v. every 12 hours), together with amoxicillin 30mg/kg i.v. every 12 hours for a total of at least 5 days.

Nosocomial pneumonia

Adults: 5 - 7mg/kg i.v. daily in divided doses for 7 days, supplemented by either cloxacillin 1 - 2 g i.v. every 6 hours or ceftazidime 1g i.v. every 8 hours.

Children: 7.5mg/kg i.v. in 1 - 3 divided doses daily for 7 days, supplemented by either cloxacillin 50mg/kg (maximum 2 g) i.v. every 6 hours or ceftazidime 25 mg/kg (maximum 1g) i.v. every 8 hours.

In hospitals with a high prevalence of meticillin-resistant Staphylococcus aureus, vancomycin 1g (children: 20mg/kg; maximum 1g) i.v. every 12 hours for 10 - 14 days should be added to the above regimens.

Acute cholecystitis

Adults: 5 - 7mg/kg i.v. daily in divided doses, together with ampicillin 1 - 2 g i.v. or i.m. every 6 hours for up to 7 days.

Children: 7.5mg/kg i.v. in 1 - 3 divided doses daily, together with ampicillin 25 - 50mg/kg (maximum 2g) i.v. or i.m. every 6 hours for up to 7 days.

Acute peritonitis

Adults: 5 - 7mg/kg i.v. daily in divided doses for at least 7 days, supplemented by ampicillin 2g i.v. or i.m. every 6 hours and metronidazole 500 mg i.v. every 8 - 12 hours.

Children: 7.5mg/kg i.v. in 1 - 3 divided doses daily for at least 7 days, supplemented by ampicillin 50mg/kg (maximum 2g) i.v. or i.m. every 6 hours and metronidazole 12.5mg/kg (maximum 500mg) i.v. every 8 - 12 hours.

For patients who are allergic to penicillins, ampicillin should be deleted from the above regimens.

Acute pyelonephritis

Adults: 5 - 7mg/kg orally daily in divided doses for 7 days, supplemented for up to 14 days by ampicillin 1 - 2 g i.v. or i.m. every 6 hours.

Children: 7.5mg/kg orally in 1 - 3 divided doses daily for 7 days, supplemented for up to 14 days by ampicillin 50mg/kg (maximum 2g) i.v. or i.m. every 6 hours.

Gangrene

Adults: 5 - 7mg/kg i.v. or i.m. daily in divided doses for at least 7 days, supplemented by benzylpenicillin 4 million IU i.v. or i.m. every 4 hours and metronidazole 500mg i.v. every 8 hours (once clinical improvement occurs, rectal formulations of metronidazole may be substituted).

Children: 7.5mg/kg i.v. or i.m. in 1 - 3 divided doses daily for at least 7 days, supplemented by benzylpenicillin 100 000IU/kg (maximum 4 million IU) i.v. or i.m. every 4 hours and metronidazole 12.5mg/kg (maximum 500mg) i.v. every 8 hours (once clinical improvement occurs, rectal formulations of metronidazole may be substituted).

For patients who are allergic to penicillins, benzylpenicillin should be replaced by clindamycin 600mg (children: 10mg/kg; maximum 450mg) orally or i.v. every 6 - 8 hours.

Contaminated soft tissue injuries

Adults: 5 - 7mg/kg i.v. or i.m. daily in divided doses for 5 - 10 days, supplemented by metronidazole 500mg i.v. every 8 hours (once clinical improvement occurs, oral or rectal formulations of metronidazole may be substituted) and cloxacillin 2g i.v. or i.m. every 6 hours (once clinical improvement occurs, cloxacillin 500 mg orally every 6 hours may be substituted).

Children: 7.5mg/kg i.v. or i.m. in 1 - 3 divided doses daily for 5 - 10 days, supplemented by metronidazole 12.5mg/kg (maximum 500mg) i.v. every 8 hours (once clinical improvement occurs, oral or rectal formulations of metronidazole may be substituted) and cloxacillin 25 - 50mg/kg (maximum 2g) i.v. or i.m. every 6 hours (once clinical improvement occurs, cloxacillin 12.5 - 25mg/kg (maximum 500mg) orally every 6 hours may be substituted).

Very severe pelvic inflammatory disease in adults

Hospitalized patients

5 - 7mg/kg i.v. or i.m. every 24 hours or 1.5 - 2.0mg/kg i.v. or i.m. every 8 hours, together with clindamycin 900mg i.v. every 8 hours for at least 4 days (or for 48 hours after clinical improvement occurs), followed by doxycycline 100mg orally every 12 hours for 10 - 14 days.

Initial empirical therapy for infective endocarditis

Adults: 2mg/kg i.v. every 8 hours, together with benzylpenicillin 3 million IU i.v. every 4 hours and cloxacillin 2g i.v. every 4 hours.

Children: 2.5mg/kg (maximum 80mg) i.v. every 8 hours, together with benzylpenicillin 50 000IU/kg (maximum 3 million IU) i.v. every 4 hours and cloxacillin 50mg/kg (maximum 2g) i.v. every 4 hours.

Patients allergic to penicillins or with nosocomial infections Adults: 2mg/kg i.v. every 8 hours, together with vancomycin 1g i.v. every 12 hours.

Children: 2.5mg/kg (maximum 80mg) i.v. every 8 hours, together with vancomycin 20mg/kg (maximum 1g) i.v. every 12 hours.

Endocarditis due to α-haemolytic streptococci

Uncomplicated endocarditis

Adults: 1mg/kg i.v. every 8 hours, together with benzylpenicillin 3 million IU i.v. every 4 hours for 2 weeks.

Children: 1mg/kg i.v. every 8 hours, together with benzylpenicillin 100 000IU/kg (maximum 3 million IU) i.v. every 4 hours for 2 weeks.

Strains highly susceptible to benzylpenicillin (MIC0.12 mg/l)

Adults: 1mg/kg i.v. every 8 hours for 2 weeks, together with benzylpenicillin 3 million IU i.v. every 4 hours for 4 weeks.

Children: 1mg/kg i.v. every 8 hours for 2 weeks, together with benzylpenicillin 100 000IU/kg (maximum 3 million IU) i.v. every 4 hours for 4 weeks.

Strains resistant to benzylpenicillin (MIC = 0.25 - 1.0 mg/l)

Adults: 1mg/kg i.v. every 8 hours for 4 - 6 weeks, supplemented for 6 weeks by either benzylpenicillin 3 - 4 million IU i.v. every 4 hours or ampicillin 2g i.v. every 4 hours.

Children: 1mg/kg i.v. every 8 hours for 4 - 6 weeks, supplemented for 6 weeks by either benzylpenicillin 100 000 IU/kg (maximum 4 million IU) i.v. every 4 hours or ampicillin 50mg/kg (maximum 2g) i.v. every 4 hours.

Endocarditis due to enterococci

Adults: 1mg/kg i.v. every 8 hours for 4 - 6 weeks, supplemented for 6 weeks by either benzylpenicillin 3 - 4 million IU i.v. every 4 hours or ampicillin 2g i.v. every 4 hours.

Children: 1mg/kg i.v. every 8 hours for 4 - 6 weeks, supplemented for 6 weeks by either benzylpenicillin 100 000 IU/kg (maximum 4 million IU) i.v. every 4 hours or ampicillin 50mg/kg (maximum 2g) i.v. every 4 hours.

Endocarditis due to meticillinsusceptible Staphylococcus aureus

Adults: 1mg/kg i.v. every 8 hours for 7 days, together with cloxacillin 2g i.v. every 4 hours for 6 weeks.

Children: 1mg/kg i.v. every 8 hours for 7 days, together with cloxacillin 50mg/kg (maximum 2g) i.v. every 4 hours for 6 weeks.

Culture-negative endocarditis

Adults: 1 mg/kg i.v. every 8 hours for 4 - 6 weeks, supplemented for 6 weeks by benzylpenicillin 3 - 4 million IU i.v. every 4 hours.

Children: 1 mg/kg i.v. every 8 hours for 4 - 6 weeks, supplemented for 6 weeks by benzylpenicillin 100 000 IU/kg (maximum 4 million IU) i.v. every 4 hours.

Prosthetic valve endocarditis

Adults: 1mg/kg i.v. every 8 hours, together with vancomycin 1g i.v. every 12 hours for 6 weeks.

Children: 1mg/kg i.v. every 8 hours, together with vancomycin 40mg/kg (maximum 1g) i.v. in 2 - 4 divided doses daily for 6 weeks.

If infection due to a Gram-negative bacterial pathogen is suspected, the dose of gentamicin should be increased to 2 mg/kg i.v. every 8 hours.

Neonatal meningitis

Meningitis due to unknown pathogen

2.5 mg/kg i.v. every 12 hours, together with ampicillin 50mg/kg (maximum 2 g) i.v. every 8 hours (neonates < 7 days: ampicillin 50mg/kg (maximum 2g) i.v. every 12 hours) for a total of 7 - 10 days.

Meningitis due to Listeria monocytogenes

2.5 mg/kg i.v. every 12 hours, together with ampicillin 50mg/kg (maximum 2 g) i.v. every 8 hours (neonates < 7 days: ampicillin 50mg/kg (maximum 2g) i.v. every 12 hours) for a total of 3 weeks.

Meningitis due to group B streptococci

2.5 mg/kg i.v. every 12 hours, together with benzylpenicillin 50 000 - 75 000 IU/kg (maximum 2 million IU) i.v. every 4 - 6 hours (neonates < 7 days: benzylpenicillin 50 000IU/kg (maximum 2 million IU) i.v. every 8 hours) for a total of 3 weeks.

Brucellosis

Adults: 5 - 7mg/kg i.v. every 24 hours for 2 weeks, together with doxycycline 100mg orally every 12 hours for 6 weeks.

Children >8 years: 7.5mg/kg i.v. in 1 - 3 divided doses daily for 2 weeks, together with doxycycline 2mg/kg (maximum 100mg) orally every 12 hours for 6 weeks.

Children ≤8 years: 7.5mg/kg i.v. in 1 - 3 divided doses daily for 2 weeks, together with sulfamethoxazole 20mg/kg + trimethoprim 4mg/kg (maximum 800mg + 160mg) orally every 12 hours for 6 weeks.

Tularaemia

Adults and children: 1.5mg/kg i.v. or i.m. every 8 hours for 7 days.

Plague

Adults and children: 1.7mg/kg i.v. or i.m. every 8 hours for 7 days.

Initial empirical therapy for septicaemia

Adults and children >5 years: 5 - 7mg/kg i.v. every 24 hours or 1.5mg/kg i.v. or i.m. every 8 hours, supplemented by either cloxacillin 2g i.v. every 4 - 6 hours or cefazolin 1 - 2 g i.v. every 8 hours or clindamycin 600 mg i.v. every 8 hours or chloramphenicol 750mg i.v. every 6 hours.

Neonates: 2.5mg/kg i.v. every 12 hours, together with ampicillin 50mg/kg (maximum 2g) i.v. every 8 hours (neonates <7 days: ampicillin 50mg/kg (maximum 2g) i.v. every 12 hours).

Prophylaxis in contaminated surgery

Adults and children: 5mg/kg i.v., together with clindamycin 600 mg i.v. at induction of anaesthesia.

Contraindications

• Pregnancy.
• Myasthenia gravis.


Precautions

Gentamicin should be administered only by trained health personnel and care must be taken to ensure that the correct dose and duration of treatment is not exceeded. When possible, audiometry should be carried out. This is particularly important in neonates, elderly patients and patients with renal impairment or if the course of treatment is for more than 7 days. The patient should be monitored for renal toxicity or ototoxicity. Prolonged treatment should be avoided.

Adverse effects

Adverse effects are generally doserelated and where possible treatment courses should not be prolonged for more than 7 days. Vestibular and auditory damage and to a lesser extent, renal toxicity are the most serious adverse effects. Rarely, hypomagnesaemia occurs during prolonged therapy. Pseudomembranous colitis has also been reported.

Drug interactions

The risk of toxicity is increased when ethacrynic acid or furosemide is administered concomitantly.

The action of neuromuscular-blocking agents may be potentiated.

Storage

Preparations for injection should be stored in vials. Solutions are stable for up to 24 hours in most infusion fluids. Injections should not be mixed with other drugs in the same syringe.

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