Aft

Uses

For the treatment of fungal corneal ulcers/ keratitis.

Trichomoniasis: Tinidazole is used for the treatment of trichomoniasis caused by Trichomonas vaginalis. The organism should be identified by appropriate diagnostic procedures. Because trichomoniasis is a sexually transmitted disease with potentially serious sequelae, partners of infected patients should be treated simultaneously in order to prevent re-infection.

Giardiasis: Tinidazole is used for the treatment of giardiasis caused by Giardia duodenalis in both adults and pediatric patients older than three years of age. Sections or subsections omitted from the full prescribing information are not listed.

Amebiasis: Tinidazole is used for the treatment of intestinal amebiasis and amebic liver abscess caused by Entamoeba histolytica in both adults and pediatric patients older than three years of age. It is not used for the treatment of asymptomatic cystpassage.

Bacterial Vaginosis: Tinidazole is used for the treatment of bacterial vaginosis (formerly referred to as Haemophilus vaginitis, Gardnerella vaginitis, nonspecific vaginitis, or anaerobic vaginosis) in non-pregnant women.

Other pathogens commonly associated with vulvovaginitis such as Trichomonas vaginalis, Chlamydia trachomatis, Neisseria gonorrhoeae, Candida albicans and Herpes simplex virus should be ruled out.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Tinidazole and other antibacterialdrugs, Tinidazole should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Aft is also used to associated treatment for these conditions: Candida intertrigo, Candida pneumonia, Candida urinary tract infection, Candidemia, Candidiasis, Coccidioidomycosis, Esophageal Candidiasis, Fungal peritonitis caused by Candida, Infections, Fungal, Meningitis, Cryptococcal, Oropharyngeal Candidiasis, Peritoneal candidiasis, Pneumonia cryptococcal, Pruritus, Skin Irritation, Systemic Candida Infections caused by Candida, Vaginal Candidiasis, Disseminated CandidiasisAmebiasis, Bacterial Vaginosis (BV), Candidal Vulvovaginitis, Giardiasis, Mixed Vaginal Infections, Nongonococcal urethritis, Sexually Transmitted Disease (STD), Trichomonas Vaginalis Infection, Trichomoniasis

How Aft works

Fluconazole is a very selective inhibitor of fungal cytochrome P450 dependent enzyme lanosterol 14-α-demethylase. This enzyme normally works to convert lanosterol to ergosterol, which is necessary for fungal cell wall synthesis. The free nitrogen atom located on the azole ring of fluconazole binds with a single iron atom located in the heme group of lanosterol 14-α-demethylase. This prevents oxygen activation and, as a result, inhibits the demethylation of lanosterol, halting the process of ergosterol biosynthesis. Methylated sterols are then found to accumulate in the fungal cellular membrane, leading to an arrest of fungal growth. These accumulated sterols negatively affect the structure and function of the fungal cell plasma membrane.

Fluconazole resistance may arise from an alteration in the amount or function of the target enzyme (lanosterol 14-α-demethylase), altered access to this enzyme, or a combination of the above. Other mechanisms may also be implicated, and studies are ongoing.

Tinidazole is a prodrug and antiprotozoal agent. The nitro group of tinidazole is reduced in Trichomonas by a ferredoxin-mediated electron transport system. The free nitro radical generated as a result of this reduction is believed to be responsible for the antiprotozoal activity. It is suggested that the toxic free radicals covalently bind to DNA, causing DNA damage and leading to cell death. The mechanism by which tinidazole exhibits activity against Giardia and Entamoeba species is not known, though it is probably similar.

Dosage

Aft dosage

Instill 1 drop to be instilled into the affected eye(s) 5 times daily.

Prevention of Postoperative Infections :

• Adult: A single oral dose of 2g approximately 12 hours before surgery.
• Children less than 12 years: Data are not available to allow dosage recommendations for children below the age of 12 years in the prophylaxis of anaerobic infections.

Trichomoniasis: a single 2 g oral dose taken with food. Treat sexual partners with the same dose and at the same time Giardiasis:

• Adults: a single 2 g dose taken with food.
• Pediatric patients older than three years of age: a single dose of 50 mg/kg (up to 2 g) with food

Amebiasis, Intestinal:

• Adults: 2 g per day for 3 days with food.
• Pediatric patients older than three years of age: 50 mg/kg/day (up to 2 g per day) for 3 days with food

Amebic liver abscess:

• Adults: 2 g per day for 3-5 days with food.
• Pediatric patients older than three years of age: 50 mg/kg/day (up to 2 g per day) for 3-5 days with food

Bacterial vaginosis: Non-pregnant, adult women: 2 g once daily for 2 days taken with food, or 1 g once daily for 5 days taken with food.

Should be taken with food. Take during or immediately after meals.

Side Effects

This drug is generally well tolerated. Eosinophillia has been reported in some patients.

Reported side effects have generally been infrequent, mild and self-limiting. Side effects from the gastrointestinal tract include nausea, vomiting, anorexia, diarrhoea and metallic taste. Hypersensitivity reactions, occasionally severe, may occur in rare cases in the form of skin rash, pruritis, urticaria and angioneurotic oedema. As with related compounds, tinidazole may produce transient leukopenia. Other rarely reported side-effects are headache, tiredness, furry tongue and dark urine.

Toxicity

Acute oral toxicity (LD50): 1271 mg/kg (rat)

Overdose information

Fluconazole overdoses have been associated with hallucination and paranoia, sometimes in combination. In cases of overdose, employ supportive treatment. Gastric lavage may be necessary. Other modalities such as forced diuresis or hemodialysis may also be used.

A note on liver toxicity

The FDA label warns that this drug carries a risk of hepatotoxicity. Rare but serious cases of serious hepatic toxicity have been reported, especially in patients with serious underlying medical conditions using fluconazole. This group of patients has an increased risk of fatality when using fluconazole. In patients with existing liver dysfunction, use caution during fluconazole therapy. Those who are found to have abnormal liver function tests during therapy should be carefully monitored for the development of increasingly severe injury to the liver. Fluconazole should be stopped if its use is likely to be the underlying cause of liver injury, and medical attention should be sought. Fluconazole induced hepatotoxicity is usually reversible.

Carcinogenesis, mutagenesis, and impairment of fertility

Fluconazole demonstrated no evidence of carcinogenic risk in mice and rats treated orally for 24 months at doses equivalent to approximately 2-7 time the recommended human dose). Male rats given fluconazole at doses equivalent to supratherapeutic human doses showed an increased incidence of hepatocellular adenomas. Cytogenetic studies in vivo and in vitro demonstrated no sign of chromosomal mutation. The significance of these findings for humans is unknown.

Use in pregnancy

There are no sufficient and well-controlled studies of fluconazole use in pregnant women. Available human data do not show an increased risk of congenital anomalies after pregnant women were treated with standard doses (27 Several case reports describe rare but striking congenital anomalies observed in infants who were exposed to fluconazole at high doses reaching 400-800 mg/day, primarily in the first trimester of pregnancy. Similar findings were observed in animal studies. If this drug is administered during pregnancy, or if the patient becomes pregnant while taking fluconazole, the risk should be discussed thoroughly.

Use in nursing

Fluconazole is secreted in breastmilk at high concentrations. Exercise caution if this drug is used during nursing.

There are no reported overdoses with tinidazole in humans. In acute studies with mice and rats, the LD 50 for mice was generally > 3,600 mg/kg for oral administration and was > 2,300 mg/kg for intraperitoneal administration. In rats, the LD 50 was > 2,000 mg/kg for both oral and intraperitoneal administration.

Precaution

Use of fluconazole may result in overgrowth of non-susceptible strains of candida other than Candida albicans

Compounds of similar chemical structure have produced various neurological disturbances such as dizziness, vertigo, uncoordination, and ataxia. If, during therapy with tinidazole, abnormal neurological signs develop, therapy should be discontinued. Use in Pregnancy & Lactation: Tinidazole is contraindicated during the first trimester of pregnancy. While there is no evidence that tinidazole is harmful during the late stages of pregnancy, its use during the last two trimesters requires that the potential benefits outweigh the possible risk to mother and foetus. Tinidazole is excreted in breast milk in concentrations similar to those seen in serum. Tinidazole can be detected in breast milk for up to 72 hours following administration. Interruption of breast-feeding is recommended during tinidazole therapy and for 3 days following the last dose.

Interaction

Fluconazole can alter pharmacokinetics of certain drugs undergoing hepatic metabolism.

The following interactions were reported with metronidazole, which is chemically-related to tinidazole.

Alcohol, disulfiram: Avoid during tinidazole use and for 3 days afterward because cramps, nausea, vomiting, headaches, and flushing may occur.

Anticoagulants, oral (eg, warfarin): Anticoagulant effects may be increased. Anticoagulant dose may need to be adjusted during coadministration and for up to 8 days after discontinuation.

Cholestyramine: Bioavailability of tinidazole may be decreased. Cyclosporine, lithium, tacrolimus: Levels may be elevated by tinidazole, increasing the risk of toxicity.

Drugs that induce CYP3A4 (eg, fosphenytoin, phenobarbital, phenytoin, rifampin): May increase metabolism of tinidazole, decreasing plasma levels and therapeutic effect.

Drugs that inhibit CYP3A4 (eg, cimetidine, ketoconazole): May prolong t½ and decrease tinidazole Cl, increasing plasma levels and risk of adverse reactions.

Fluorouracil: Cl may be decreased by tinidazole, increasing the risk of adverse reactions

Fosphenytoin, phenytoin: The t½ may be prolonged and Cl reduced by tinidazole, increasing the risk of adverse reactions.

Oxytetracycline: Therapeutic effect of tinidazole may be decreased.

Volume of Distribution

The apparent volume of distribution is said to be similar to the volume of distribution of total body water. One clinical study of healthy volunteers administered 50 mg/kg of fluconazole was 39L, based on a body weight of 60kg.

Fluconazole shows substantial penetration in many body fluids, which is a property that renders it an ideal treatment for systemic fungal infections, especially when administered over a longer time. Fluconazole is found in high concentrations in the stratum corneum and dermis-epidermis of skin, in addition to eccrine sweat. Fluconazole is found to accumulate especially well in the stratum corneum, which is beneficial in superficial fungal infections.[L6496] Saliva and sputum concentrations of fluconazole are found to be similar to the plasma concentrations. In patients diagnosed with fungal meningitis, fluconazole CSF (cerebrospinal fluid) levels are measured to be about 80% of the corresponding plasma levels. Therefore, fluconazole crosses the blood-brain barrier[L6496]. The meninges are increasingly permeable to fluconazole in states of inflammation, facilitating treatment in meningitis.

• 50 L

Elimination Route

The pharmacokinetic properties of fluconazole are comparable after administration by the intravenous (IV) and oral (PO) routes. In healthy volunteers, the bioavailability of orally administered fluconazole is measured to be above 90%. It is extensively absorbed in the gastrointestinal tract when an oral dose is taken. Oral absorption is not affected by food intake with fluconazole but may increase the time until the maximum concentration is reached.

Tmax (or the time taken to achieve the maximum concentration) in one clinical study of healthy patients receiving 50 mg/kg of fluconazole was 3 hours.

Peak plasma concentrations (Cmax) in fasting and healthy volunteers occur between 1-2 hours post-dose. Steady-state concentrations are achieved within 5 to 10 days after oral doses of 50-400 mg administered once daily. Administration of a loading dose on the first day of fluconazole treatment, or twice the usual daily dose, leads to plasma concentrations close to steady-state by the second day. Mean AUC (area under the curve) was 20.3 in healthy volunteers receiving 25 mg of fluconazole.

A note on the capsule and powder form and malabsorption syndromes

The capsule forms of fluconazole often contain lactose and should not be administered with hereditary galactose intolerance, Lapp lactase enzyme deficiency, or malabsorption of glucose/galactose. The powder form, used for the oral suspension, lists sucrose as an ingredient and should not be used in patients who have been diagnosed with fructose, glucose/galactose malabsorption, and sucrase-isomaltase enzyme deficiency.

Rapidly and completely absorbed under fasting conditions. Administration with food results in a delay in T_max of approximately 2 hours and a decline in C_max of approximately 10% and an AUC of 901.6 ± 126.5 mcg hr/mL.

Half Life

The terminal elimination half-life in the plasma is approximately 30 hours (range: 20-50 hours) after oral administration. The long plasma elimination half-life supports a single dose therapy for vaginal candidiasis, once daily and once weekly dosing for other indications.[L6496]. Patients with renal failure may require dosage adjustment, and half-life can be significantly increased in these patients.

The elimination half-life is 13.2±1.4 hours and the plasma half-life is 12 to 14 hours.

Clearance

This drug is mainly eliminated by the kidneys and the mean body clearance in adults is reported to be 0.23 mL/min/kg. One clinical study of healthy subjects showed total clearance of 19.5 ± 4.7 mL/min and renal clearance of 14.7 ± 3.7 mL/min (1.17 ± 0.28 and 0.88 ± 0.22 L/h).

Clearance in the pediatric population varies according to age, as does clearance in patients with renal failure.

Elimination Route

In normal volunteers, fluconazole is cleared primarily by renal excretion, with approximately 80% of the administered dose measured in the urine as unchanged drug. About 11% of the dose is excreted in the urine as metabolites.. A study of a 50mg radiolabeled dose of fluconazole revealed that 93.3% of the dose was found excreted in the urine.

A note on renal failure

The pharmacokinetics of fluconazole are significantly affected by renal dysfunction. The dose of fluconazole may need to be reduced in patients with decreased renal function. A 3-hour hemodialysis treatment lowers plasma fluconazole concentrations by about 50%.

Tinidazole crosses the placental barrier and is secreted in breast milk. Tinidazole is excreted by the liver and the kidneys. Tinidazole is excreted in the urine mainly as unchanged drug (approximately 20-25% of the administered dose). Approximately 12% of the drug is excreted in the feces.

Pregnancy & Breastfeeding use

Use in pregnancy: Pregnancy category C. There are no adequate and well-controlled studies in pregnant women. Fluconazole should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Use in lactation: Nursing mother should not be given as the drug is excreted in breast milk in concentration similar to plasma.

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.

Contraindication

The drug is contraindicated in patients with hypersensitivity to azoles.

As with other compounds of similar structure, tinidazole, is contraindicated in patients having, or with a history of, blood dyscrasias although no persistent haematological abnormalities have been noted in clinical or animal studies. Tinidazole should be avoided in patients with organic neurological disorders. Tinidazole should not be administered to patients with known hypersensitivity to the compound.

Special Warning

Renal Impairment: Haemodialysis: Additional dose equal to half the usual dose at the end of haemodialysis.

Storage Condition

Keep out of the reach of children. Store in a cool, dry place, away from heat and direct light. Do not use more than 4 weeks after opening the bottle

Store at room temperature & protected from light.

Innovators Monograph

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