A fixed-dose combination (FDC) antifungal and antiprotozoal/antibacterial agent. Fluconazole is a triazole antifungal that inhibits fungal cytochrome P450 14α-demethylase, disrupting ergosterol synthesis in fungal cell membranes. Tinidazole is a nitroimidazole antimicrobial effective against anaerobic bacteria and protozoa by damaging their DNA. This combination is primarily used in gynecological infections where mixed fungal (Candida) and anaerobic/trichomonal infections are suspected or confirmed. Its use as an FDC is controversial and has been scrutinized by regulatory authorities due to potential for inappropriate use and increased antimicrobial resistance.
Adult: Commonly available as a single-dose therapy: Fluconazole 150 mg + Tinidazole 500 mg or 1000 mg, taken orally as a single dose. Some regimens may use Fluconazole 150 mg + Tinidazole 2 gm as a single dose. A 3-day course (once daily) is also marketed. MUST be taken with or after food.
Note: Take orally with a full glass of water, during or immediately after a meal to minimize gastrointestinal upset. Do not crush or chew the tablet unless specified. Complete the full prescribed course even if symptoms improve.
Fluconazole exerts its antifungal effect by selectively inhibiting the fungal cytochrome P450 enzyme lanosterol 14-α-demethylase. This inhibition blocks the conversion of lanosterol to ergosterol, an essential component of the fungal cell membrane, leading to increased membrane permeability and inhibition of fungal growth. Tinidazole, after entering the microbial cell, is reduced by nitroreductase enzymes in anaerobic bacteria and protozoa. This reduction generates reactive nitro radical anions that cause strand breaks in microbial DNA, inhibiting nucleic acid synthesis and leading to cell death.
Pregnancy: Pregnancy Category C (US FDA). Tinidazole is contraindicated in the first trimester. Fluconazole is contraindicated for multiple-dose treatment (>150 mg single dose) due to risk of birth defects. This FDC should be AVOIDED during pregnancy, especially first trimester. Use only if potential benefit justifies potential fetal risk in later trimesters.
Driving: May cause dizziness, vertigo, or visual disturbances. Patients should be cautioned about driving or operating machinery until they are sure they are not affected.
| Warfarin | Fluconazole inhibits metabolism, increasing INR and bleeding risk. | Major |
| Sulfonylureas (e.g., Glipizide) | Fluconazole increases sulfonylurea levels, causing hypoglycemia. | Major |
| Phenytoin | Fluconazole increases phenytoin levels; phenytoin may decrease fluconazole levels. | Major |
| Rifampicin | Decreases Fluconazole levels significantly. | Major |
| Cyclosporine, Tacrolimus | Fluconazole increases calcineurin inhibitor levels, risking nephrotoxicity. | Major |
| Statins (Metabolized by CYP3A4 e.g., Atorvastatin) | Increased risk of myopathy/rhabdomyolysis. | Moderate |
| Oral Contraceptives | Potential for decreased efficacy; use backup method. | Moderate |
| Lithium | Tinidazole may increase lithium levels, causing toxicity. | Moderate |
| Disulfiram | Increased risk of psychotic reactions with Tinidazole. | Major |
| Alcohol & Alcohol-containing products | Disulfiram-like reaction with Tinidazole (flushing, nausea, vomiting, palpitations). | Major |