Tinidazole
**Tinidazole** is a second-generation **5-nitroimidazole** antimicrobial and antiprotozoal agent, structurally and pharmacologically similar to metronidazole. Key clinical highlights include: * **Extended Half-Life**: Tinidazole has a longer duration of action compared to metronidazole, allowing for less frequent dosing (e.g., once daily in cats compared to twice daily for metronidazole). * **Anaerobic Efficacy**: It exhibits excellent activity against obligate anaerobes, particularly *Porphyromonas* spp. found in canine gingiva, making it highly useful for severe dental and oral infections. * **Antiprotozoal Activity**: It is utilized as an alternative treatment for *Giardia*, *Entamoeba histolytica*, *Trichomonas*, and *Balantidium* infections. * **Tritrichomonas foetus**: While ronidazole is typically the drug of choice for feline *T. foetus*, tinidazole has been investigated as an alternative, though it may only suppress shedding rather than fully eradicate the organism in some cases. > **Clinical Pearl**: Because of its intensely bitter taste, compounding into capsules or heavily flavored suspensions is highly recommended, especially for feline patients who may hypersalivate or reject the medication.
กลไกการออกฤทธิ์: Tinidazole is a prodrug that requires activation within susceptible organisms. * **Uptake**: The drug diffuses into the target anaerobic bacteria or protozoa. * **Reduction**: Inside the cell, the nitro group of tinidazole is reduced by electron-transport proteins (such as **ferredoxin** or **nitroreductase** enzymes) specific to anaerobic metabolism. * **DNA Disruption**: This reduction → generates highly reactive, unidentified polar nitro radical anions → these radicals bind to and disrupt **DNA and nucleic acid synthesis** → leading to strand breakage and rapid cell death. This mechanism makes it rapidly **bactericidal**, **trichomonacidal**, and **amebicidal**.
ขนาดยาตามชนิดสัตว์
- Stomatitis, anaerobic infections · 15 mg/kg PO q24h · PO · q24h · 7 days
- Tritrichomonas foetus (experimental) · 30 mg/kg PO once daily · PO · q24h · 14 days · Decreased fecal shedding but failed to eradicate infection in 2 of 4 cats.
- Susceptible anaerobic infections · 10-15 mg/kg PO q12h · PO · q12h
- Stomatitis, anaerobic infections · 15-25 mg/kg PO q12h · PO · q12h · 7 days
- Giardiasis · 44 mg/kg PO q24h · PO · q24h · 6 days · Potentially useful for trichomoniasis, amebiasis, and balantidiasis.
ขนาดยาเป็นข้อมูลอ้างอิงทางคลินิกสำหรับสัตวแพทย์ผู้มีใบอนุญาต โปรดตรวจสอบกับฉลากล่าสุดและผู้ป่วยแต่ละรายเสมอ
วิธีการให้ยา
ข้อห้ามใช้
- Hypersensitivity to tinidazole or other 5-nitroimidazoles (e.g., metronidazole, ronidazole)
- Food-producing animals (prohibited use)
อาการไม่พึงประสงค์
- Vomiting
- Inappetence
- Diarrhea
- Neurotoxicity (ataxia, nystagmus, seizures)
- Hypersalivation (due to bitter taste)
อันตรกิริยาระหว่างยา
- Alcohol · May induce a disulfiram-like reaction (nausea, vomiting, cramps).
- Cimetidine · May decrease the metabolism of tinidazole and increase the likelihood of dose-related side effects.
- Ketoconazole · May decrease the metabolism of tinidazole and increase the likelihood of dose-related side effects.
- Cyclosporine · Tinidazole may increase the serum levels of cyclosporine.
- Tacrolimus (systemic) · Tinidazole may increase the serum levels of tacrolimus.
- Fluorouracil (systemic) · Tinidazole may increase the serum levels of fluorouracil and increase the risk of toxicity.
- Lithium · Tinidazole may increase lithium serum levels and increase the risk for lithium toxicity.
- Oxytetracycline · May antagonize the therapeutic effects of metronidazole (and presumably tinidazole).
- Phenobarbital · May increase the metabolism of tinidazole thereby decreasing blood levels.
- Rifampin · May increase the metabolism of tinidazole thereby decreasing blood levels.
- Phenytoin · May increase the metabolism of tinidazole thereby decreasing blood levels.
- Warfarin · May prolong the prothrombin time (PT). Avoid concurrent use if possible; otherwise, intensify monitoring.
การติดตาม
- Clinical efficacy in treating the infection
- Gastrointestinal tolerance
- Neurological signs (ataxia, nystagmus, seizures)
การได้รับยาเกินขนาด
Very limited information is available. In rodent studies, the oral LD50 was >3.6 g/kg (mice) and >2 g/kg (rats). Treatment of acute overdoses is **symptomatic and supportive**. * **Decontamination**: Gastric lavage or induction of emesis may be helpful if performed shortly after ingestion and the patient is neurologically appropriate. * **Clearance**: Hemodialysis can remove approximately 43% of the drug in the body (based on human data) in a 6-hour session.
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