Tobramycin

INTRODUCTION

Indications

Treatment of serious gram-negative bacillary infections and infections caused by staphylococci when penicillins or other less toxic drugs are contraindicated. Ophthalmic: Treatment of localized infections due to susceptible organisms. Inhalation: Management of cystic fibrosis patients with Pseudomonas aeruginosa.

Action

Inhibits protein synthesis in bacteria at level of 30S ribosome. Therapeutic Effects: Bactericidal action. Spectrum: Most aminoglycosides 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.

Adverse Reactions/Side Effects

EENT: ototoxicity (vestibular and cochlear) Ophthalmic only: burning, stinging, blurred vision (ointment only). Inhalation only: tinnitus, voice alteration. GU: nephrotoxicity. F and E: hypomagnesemia. 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 ototoxicity, including hearing loss, tinnitus, and balance problems (See Appendix E for fall assessment and prevention). Report these signs, and caution the patient and family/caregivers to guard against falls and trauma.

• Monitor signs of low magnesium levels (hypomagnesemia), such as lethargy, irritability, insomnia, muscle tremors, and confusion. Notify physician of these signs.

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.

• Advise patient to report any vision disturbances or eye pain and inflammation that occurs during local (ophthalmologic) administration.

Pharmacokinetics

Absorption: Well absorbed after IM administration. IV administration results in complete bioavailability. Low absorption follows administration by inhalation.

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

Metabolism and Excretion: Excretion is >90% renal.

Half-life: Neonates: 2–11 hr; Infants: 3–5 hr; Children: 1–3 hr; Adolescents: 0.5–2.5 hr; Adults: 2–4 hr (↑ in renal impairment to 5–70 hr).