Gentamicin

INTRODUCTION

Indications

Treatment of serious gram-negative bacterial infections and infections caused by staphylococci when penicillins or other less toxic drugs are contraindicated. In combination with other agents in the management of serious enterococcal infections. Prevention of infective endocarditis. Topical, Ophth: Treatment of localized infections due to susceptible organisms.

Action

Inhibits protein synthesis in bacteria at level of 30S ribosome. Therapeutic Effects: Bactericidal action. Spectrum: Notable for activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Proteus, Serratia, Acinetobacter, Staphylococcus aureus. In treatment of enterococcal infections, synergy with a penicillin is required. Not active against Streptococci, Anaerobes.

Adverse Reactions/Side Effects

CNS: ataxia, vertigo. EENT: ototoxicity (vestibular and cochlear). GU: nephrotoxicity. MS: muscle paralysis (high parenteral doses). Misc: hypersensitivity reactions.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Monitor signs of hypersensitivity reactions, including pulmonary symptoms (tightness in the throat and chest, wheezing, cough dyspnea) or skin reactions (rash, pruritus, urticaria). Notify physician or nursing staff immediately if these reactions occur.

• Report any muscle weakness or paralysis that occurs following injection of high doses.

• Monitor signs of ataxia and vertigo that might affect gait, balance, and other functional activities. Report balance problems and functional limitations to the physician and nursing staff, and caution the patient and family/caregivers to guard against falls and trauma.

• Monitor signs of ototoxicity, including hearing loss, tinnitus, and balance problems (See Appendix E for fall assessment and prevention). Report these signs to the physician, and caution the patient and family/caregivers to guard against falls and trauma.

Interventions

• Always wash hands thoroughly and disinfect equipment (whirlpools, electrotherapeutic devices, treatment tables, and so forth) to help prevent the spread of infection. Employ universal precautions or isolation procedures as indicated for specific patients.

Patient/Client-Related Instruction

• Advise patient to report signs of nephrotoxicity, including blood or pus in urine, decreased urine output, fatigue, and weight gain from fluid retention.

Pharmacokinetics

Absorption: Well absorbed after IM administration. IV administration results in complete bioavailability. Some absorption follows administration by other routes.

Distribution: Widely distributed throughout extracellular fluid; crosses the placenta; small amounts enter breast milk. Poor penetration into CSF.

Metabolism and Excretion: >90% excreted unchanged by kidneys.

Half-life: Neonates <7 days: 3–11.5 hr; Neonates 7–30 days: 3–6 hr; Infants: 3–5 hr; Children: 1–3 hr; Adolescents: 0.5–2.5 hr; Adults: 2–4 hr (increased in renal impairment).