클래리트로마이신

마크로라이드계 항생제

클래리트로마이신은 에리트로마이신과 밀접한 관련이 있는 반합성 **마크로라이드계 항생제**입니다. 락톤 고리의 6번 위치가 메틸화되어 구조적으로 변형되었으며, 이로 인해 모화합물에 비해 위산에 대한 안정성이 향상되고 경구 생체이용률이 높으며 항균 스펙트럼이 더 넓어졌습니다. **주요 임상 특징:** * **항균 스펙트럼:** 에리트로마이신과 유사하지만 **비정형 항산균**(예: *Mycobacterium avium* complex), *헬리코박터* 종 및 *Rhodococcus equi*에 매우 효과적입니다. * **임상적 유용성:** 소동물에서는 주로 비정형 항산균 감염(고양이 나병 또는 개 나병양 육아종 등) 및 *헬리코박터* 제균 요법에 사용됩니다. 마의학에서는 망아지의 *Rhodococcus equi* 폐렴 치료에 핵심적인 약물입니다. * **내약성:** 일반적으로 에리트로마이신보다 내약성이 좋으며, 위장관 운동 촉진(모틸린 수용체 작용) 효과가 적어 위장관 부작용이 덜합니다. > **임상 팁:** 클래리트로마이신은 사이토크롬 P450 3A(CYP3A) 효소계의 강력한 억제제입니다. 이 경로를 통해 대사되는 다른 약물과 병용할 경우 독성을 피하기 위해 주의 깊은 검토가 필요합니다.

작용 기전: Clarithromycin is typically **bacteriostatic**, though it can be bactericidal at high concentrations against highly susceptible organisms. * **Mechanism:** It penetrates the bacterial cell wall and reversibly binds to the **P site of the 50S ribosomal subunit**. * **Pathway:** Binding → Inhibition of RNA-dependent protein synthesis (blocks transpeptidation and translocation) → Suppression of bacterial growth. * **Post-Antibiotic Effect (PAE):** Macrolides generally exhibit a prolonged PAE against Gram-positive pathogens, allowing for sustained efficacy even when plasma levels drop below the MIC.

동물 종별 용량

Cats

Treatment of feline leprosy · 62.5 mg per cat q12h · PO · q12h · Used in a regimen of 2 or 3 drugs including clofazimine and/or rifampin.
Treatment of Nocardia (N. nova) infections · 62.5-125 mg (total dose per cat) PO twice daily · PO · q12h · Combination therapy with amoxicillin and/or doxycycline.
Treatment of H. pylori infections · 7.5 mg/kg PO twice daily · PO · q12h · 14 days · Combination therapy with metronidazole and amoxicillin.
Treatment of M. tuberculosis-bovis variant infections · 5-10 mg/kg PO q12h · PO · q12h · At least 2 months, then maintenance for 4 months · Used with rifampin and enrofloxacin.
Susceptible infections · 7.5 mg/kg PO q12h · PO · q12h

Ferrets

Treatment of Helicobacter mustelae infections · 12.5 mg/kg PO q12h · PO · q12h · 14 days · With ranitidine bismuth citrate. Same regimen given q8h is also published.
Treatment of Helicobacter mustelae infections · 12.5-50 mg/kg q8-24h · PO · q8-24h · With omeprazole at 0.7 mg/kg PO once daily.

Horses

Treatment of Rhodococcus equi infection in foals · 7.5 mg/kg PO q12h · PO · q12h
Treatment of Rhodococcus equi infection in foals · 7.5 mg/kg PO q12h · PO · q12h · In combination with rifampin at 5 mg/kg PO q12h or 10 mg/kg PO q24h.

투여 경로

금기

Known hypersensitivity to clarithromycin or other macrolide antibiotics (e.g., erythromycin, azithromycin)
Concurrent use with cisapride (due to risk of fatal cardiac arrhythmias)

이상반응

Gastrointestinal disturbances (nausea, vomiting, anorexia, diarrhea)
Pinnal or generalized erythema (specifically noted in cats)
Transient, mild BUN elevation
Prolonged QT interval / torsades de pointes (rare)
Hepatotoxicity (rare)
Thrombocytopenia (rare)
Pseudomembranous colitis secondary to Clostridium difficile (reported in humans)

약물 상호작용

Cisapride · Clarithromycin inhibits cisapride metabolism; concurrent use is contraindicated due to risk of severe cardiac arrhythmias.
Fluconazole · May increase clarithromycin serum levels.
Digoxin · Clarithromycin may increase serum levels of digoxin.
Omeprazole · Concurrent use can increase the plasma levels of both drugs.
Warfarin · May potentiate the effects of oral anticoagulant drugs.
Zidovudine · Clarithromycin may decrease serum concentrations of zidovudine.
CYP3A Substrates (Alfentanil, Bromocriptine, Buspirone, Carbamazepine, Methylprednisolone, Midazolam, Alprazolam, Triazolam, Rifabutin, Tacrolimus, Theophylline) · Clarithromycin inhibits CYP3A, potentially increasing plasma concentrations and toxicity of these drugs. Therapeutic monitoring or dose reduction may be required.
Disopyramide · Increased levels and risk of prolonged QT interval.
Quinidine · Increased levels and risk of prolonged QT interval.

모니터링

Clinical efficacy (resolution of infection)
Gastrointestinal adverse effects
Signs of erythema (especially in cats)
Potential drug interactions if on concurrent medications

과용량

Overdoses of clarithromycin are generally not life-threatening and primarily result in **gastrointestinal distress** (vomiting, diarrhea, cramping). * **Treatment:** For recent, large ingestions, administration of activated charcoal with a cathartic may help remove unabsorbed drug. * **Note:** Forced diuresis, peritoneal dialysis, or hemodialysis are **not effective** in enhancing the elimination of clarithromycin from the body.

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