利福平
利福平是一種高脂溶性、半合成的抗菌藥物，屬於利福黴素類。在獸醫學中，它是治療深層細胞內感染的基石療法，特別是馬駒的**馬紅球菌 (Rhodococcus equi)** 感染。 由於其具有穿透乾酪樣物質、骨骼、膿瘍和巨噬細胞的卓越能力，對抗細胞內病原體（如分枝桿菌、金黃色葡萄球菌和胞內勞森菌）非常有效。在高濃度下，它也具有一定的抗真菌和抗病毒活性。 > **臨床要點：** 利福平**絕對不能**作為單一療法使用。細菌可透過單一步驟突變迅速產生抗藥性。它總是與其他抗菌藥物（例如馬用的紅黴素或克拉黴素，或狗用的頭孢菌素/磺胺類藥物）合併開立。
作用機制: Rifampin can be bactericidal or bacteriostatic depending on the concentration and the susceptibility of the target organism. * **Target:** It binds strongly to the beta subunit of bacterial **DNA-dependent RNA polymerase**. * **Pathway:** Binding inhibits the enzyme → suppresses the initiation of chain formation for RNA synthesis → halts bacterial protein production → cell death. * **Selectivity:** Rifampin is highly selective for bacterial enzymes and does not inhibit mammalian RNA polymerase, providing a wide margin of safety for the host.
各物種劑量
- Susceptible infections (e.g., mycobacteriosis, Rhodococcus equi, chlamydiosis, bartonellosis) · 10-15 mg/kg · PO · q24h · Duration depends on the specific infection being treated · Must be used in combination with other antimicrobial drugs to prevent the emergence of resistant organisms.
- Treatment of Rhodococcus equi (C. equi) infections in foals · 5 mg/kg PO two times daily · PO · q12h · With erythromycin 15-25 mg/kg, PO q12-24h. Clarithromycin may be superior due to erythromycin side effects.
- Treatment of Rhodococcus equi (C. equi) infections in foals · 5 mg/kg PO two times daily or 10 mg/kg PO once daily · PO · q12h or q24h · 4-9 weeks · With erythromycin 25 mg/kg, PO q6-8h.
- Treatment of proliferative enteropathy caused by Lawsonia intracellularis in foals · 10 mg/kg PO once daily · PO · q24h · minimum of 21 days · In combination with erythromycin estolate (25 mg/kg PO q6-8h)
- Treatment of mycobacteriosis · 45 mg/kg PO once daily · PO · q24h · In combination with ethambutol (30 mg/kg PO once daily) and one of the following: clofazimine (6 mg/kg PO once daily) or isoniazid (30 mg/kg PO once daily).
- Combination therapy of atypical Mycobacteria infections; treatment of resistant Staph endocarditis · 10-20 mg/kg PO q8-12h · PO · q8-12h · In combination with amoxicillin/clavulanate or trimethoprim/sulfa
給藥途徑
禁忌症
- Hypersensitivity to rifampin or other rifamycins
- Use with extreme caution in patients with preexisting hepatic dysfunction
- Pregnancy (teratogenic at high doses)
- Pre-existing liver disease or hepatic dysfunction
不良反應
- Red-orange discoloration of bodily fluids (urine, tears, sweat, saliva)
- Gastrointestinal distress (anorexia, vomiting, diarrhea)
- Elevated liver enzymes and potential hepatotoxicity
- Rashes and erythema (noted in cats and humans)
- In horses (especially with macrolides): mild diarrhea to severe enterocolitis, hyperthermia, and acute respiratory distress
- Intravenous use in horses (rare): CNS depression, sweating, hemolysis, anorexia
- Elevated serum hepatic enzymes
- Clinical hepatitis
- Orange-red discoloration of urine, saliva, tears, and feces
- Gastrointestinal upset (anorexia, vomiting, diarrhea)
藥物相互作用
- Fluoroquinolones · In vitro antagonism has been reported; concurrent use should be avoided.
- Barbiturates · Decreased serum levels and shortened half-life due to hepatic microsomal enzyme induction by rifampin. · major
- Benzodiazepines (e.g., diazepam) · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Chloramphenicol · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Corticosteroids · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Dapsone · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Ketoconazole · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Propranolol · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Quinidine · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Warfarin · Decreased serum levels and shortened half-life due to hepatic enzyme induction.
- Theophylline · Increased rate of metabolism of theophylline due to hepatic enzyme induction. · major
- Itraconazole · Increased rate of metabolism of itraconazole due to hepatic enzyme induction, leading to subtherapeutic antifungal levels. · major
監測
- Clinical efficacy and resolution of infection
- Liver function tests (especially with long-term therapy)
- Chest radiographs and plasma fibrinogen levels (prognostic indicators for C. equi infections in foals after 1 week of therapy)
- Baseline and periodic serum hepatic enzyme levels (ALT, AST, ALP, Bilirubin)
- Clinical signs of hepatitis (icterus, anorexia, vomiting, lethargy)
過量
Clinical signs of oral rifampin overdose are generally extensions of its adverse effects, including **gastrointestinal distress**, **orange-red coloring of fluids**, and **skin erythema** (noted particularly in cats). Massive overdoses carry a significant risk of **hepatotoxicity**. Dogs may exhibit central nervous system depression. **Treatment:** * Empty the gut following standard decontamination protocols for massive oral overdosage. * Monitor liver enzymes closely. * Initiate supportive treatment as necessary.
VetSheet 藥物參考供持牌獸醫專業人員作臨床決策輔助之用,不能取代專業判斷或廠方最新藥品說明書。