토브라마이신

아미노글리코사이드계 항생제Critically Important

토브라마이신은 주로 심각한 그람 음성 호기성 세균 감염에 탁월한 효능을 나타내는 강력한 비경구용 **아미노글리코사이드계 항생제**입니다. **주요 임상적 특징:** * **항균 스펙트럼:** 호기성 그람 음성 간균(예: 녹농균, 대장균, 클레브시엘라, 프로테우스) 및 일부 호기성 그람 양성균(예: 포도상구균)에 매우 효과적입니다. 혐기성 세균 및 진균에는 효과가 없습니다. * **임상적 유용성:** 내재된 독성으로 인해 전신적 사용은 일반적으로 독성이 적은 다른 항생제가 듣지 않는 심각하고 생명을 위협하는 감염이나 알려진 겐타마이신 내성 균주를 치료할 때로 제한됩니다. * **독성 프로파일:** 모든 아미노글리코사이드계와 마찬가지로 **신독성** 및 **이독성**의 심각한 위험을 수반합니다. 일부 실험실 증거에 따르면 겐타마이신보다 신독성이 약간 낮을 수 있지만 임상적으로는 여전히 논란의 여지가 있습니다. > **임상 핵심:** 아미노글리코사이드계는 **농도 의존적 살균 활성**과 유의미한 **항생제 후 효과(PAE)**를 나타냅니다. 이러한 약동학/약력학적 프로파일은 현대의 고용량, 연장된 간격(1일 1회) 투여 방식을 강력히 뒷받침합니다. 이 접근법은 세균 사멸을 위한 $C_{max}$/MIC 비율을 최대화하는 동시에 신세뇨관 세포가 약물을 제거할 수 있는 휴약 기간을 제공하여 신독성을 최소화합니다.

작용 기전: Tobramycin is a **bactericidal** antibiotic that disrupts bacterial protein synthesis. * **Cellular Entry:** The drug enters the bacterial cell via an **oxygen-dependent active transport mechanism**. > **Note:** Because this transport requires oxygen, aminoglycosides are completely ineffective against obligate anaerobic bacteria and have reduced efficacy in anaerobic environments (e.g., abscesses, necrotic tissue). * **Target Binding:** Once inside, tobramycin irreversibly binds to the **30S ribosomal subunit**. * **Mechanism:** Binding → misreading of mRNA → incorporation of incorrect amino acids into the growing peptide chain → production of non-functional or toxic proteins → bacterial cell death. * **Environmental Factors:** Antimicrobial activity is significantly enhanced in an **alkaline environment** and diminished in acidic, purulent conditions.

동물 종별 용량

Cats

General susceptible infections · 2 mg/kg · IV, IM, SC · q8h · Consider consolidating to once-daily dosing.
Susceptible UTI · 1-2 mg/kg · SC · q8h
Sepsis · 2-4 mg/kg · IV · q8h
Soft tissue, systemic infections · 2 mg/kg IV, IM or SC q12h or 4 mg/kg IV, IM, SC q24h · IV, IM, SC · q12h or q24h · <= 5 days
Persistent bacteremia · 2 mg/kg IV, IM, SC q8h or 6 mg/kg IV, IM or SC q24h · IV, IM, SC · q8h or q24h · <= 5 days
Gram-negative infections · 4-6 mg/kg · IV/IM/SC · q24h · Assess according to clinical response · Cats may be more sensitive to toxicity. For severe infections (including sepsis), doses as high as 12 mg/kg/day have been advocated, but should be used with caution.

Horses

Susceptible infections · 4 mg/kg · IV · q24h · Allows achievement of Cmax/MIC ratio higher than 10 for pathogen strains with a MIC of 1 microgram/mL.

Birds

Susceptible infections · 5 mg/kg · IM · q12h
Susceptible infections · 2.5-5 mg/kg/day · Parenteral · Daily

SmallMammals

투여 경로

IVIMSCtopicalinhalationophthalmic

금기

Known hypersensitivity to aminoglycosides
Rabbits and hares (causes fatal disruption of GI flora)
Pre-existing severe renal disease (unless benefits outweigh risks)
Dehydration
Corneal ulceration (specifically for ophthalmic preparations)

이상반응

Nephrotoxicity (acute tubular necrosis)
Ototoxicity (vestibular and auditory damage, potentially irreversible)
Neuromuscular blockade
Facial edema
Pain or inflammation at the injection site
Peripheral neuropathy
Hypersensitivity reactions
Rarely: GI signs, hematologic, and hepatic effects
Ototoxicity (vestibular and auditory damage)
Neuromuscular blockade (rare)

약물 상호작용

Beta-lactam antibiotics (penicillins, cephalosporins) · Synergistic antibacterial effects in vivo; however, can cause physical inactivation of aminoglycosides if mixed in the same syringe or IV line, or in vivo in patients with severe renal failure. · moderate
Cephalosporins · Potential for additive nephrotoxicity (historically documented with older generation cephalosporins like cephalothin).
Loop Diuretics (furosemide, torsemide) · Increased risk of nephrotoxicity and ototoxicity.
Osmotic Diuretics (mannitol) · Increased risk of nephrotoxicity and ototoxicity.
Other Nephrotoxic Drugs (cisplatin, amphotericin B, polymyxin B, vancomycin) · Significantly increased risk of acute kidney injury.
Neuromuscular Blocking Agents & General Anesthetics · Concomitant use can potentiate and prolong neuromuscular blockade, potentially leading to respiratory paralysis.
Amphotericin B · Increased risk of nephrotoxicity · major
Furosemide · Increased risk of ototoxicity and nephrotoxicity · major
Heparin · In vitro chemical inactivation if mixed · minor
Pancuronium · Enhanced non-depolarizing neuromuscular blockade · moderate

모니터링

Clinical efficacy (resolution of fever, improved clinical signs, negative follow-up cultures)
Renal toxicity: Baseline and serial urinalysis (monitoring for tubular casts, which are often the first sign of impending toxicity), urine specific gravity, serum creatinine, and BUN
Gross monitoring for vestibular toxicity (head tilt, nystagmus, ataxia) or auditory toxicity (deafness)
Therapeutic drug monitoring (peak and trough serum levels) is highly recommended to ensure efficacy and prevent toxicity
Urinalysis (daily, looking for cellular casts as an early warning)
Serum creatinine and BUN (baseline and periodically)
Hydration status and urine output
Auditory and vestibular function

과용량

In the event of an inadvertent overdose, rapid intervention is required to prevent permanent renal and otic damage: * **Hemodialysis:** Highly effective in reducing serum levels of the drug, though rarely available in veterinary practice. * **Peritoneal Dialysis:** Can reduce serum levels but is significantly less efficacious than hemodialysis. * **Drug Complexation:** Intravenous administration of carbenicillin or ticarcillin (12-20 grams/day in humans) can complex with tobramycin in the blood, inactivating it. This is reportedly nearly as effective as hemodialysis.

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