Trimethoprim

Drug #738

Trimethoprim is a synthetic antibacterial agent, closely related to the antimalarial agent pyrimethamine. Chemically Trimethoprim is trimethoxybenzylpyrimidine. It has activity against both gram-positive and gram-negative bacteria. Trimethoprim is commonly used systemically for the treatment and prophylaxis of uncomplicated urinary tract infections, for traveler's diarrhea, and, when combined with either sulfamethoxazole or dapsone, for prophylaxis and treatment of Pneumocystis carinii infections. It was originally made available in combination with sulfamethoxazole in 1973, then was approved by the FDA for use as a single agent in 1980. Antibiotics require constant drug level in body for therapeutic effect. This is achieved by taking the drug at regular intervals of time throughout the day and night as prescribed. Trimethoprim is important to take the drug for the full time period as prescribed. Discontinuation of the drug, may result in ineffective treatment.

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Primary Characteristics

It is of Synthetic origin and belongs to Pyrimidine.

It belongs to Dihydrofolate reductase inhibitor pharmacological group on the basis of mechanism of action and also classified in Antibiotics pharmacological group.

Molecular Weight: 290.3 · pK_a: 7.3 · Solubility in Water: 1 in 2300 · Solubility in Alcohol: 1 in 300 · Non-proprietary name: Trimethoprim.

Pharmacokinetics

Absorption: Trimethoprim has an oral bioavailability is 96.5% (±1.5%), pre-systemic (first-pass) metabolism accounts for 0.5% (±0.5%).

Distribution: Trimethoprim has a volume of distribution is 70 - 100 litre. plasma protein binding is 42 - 46 %.

Elimination: plasma half-life is 8.6 - 17 hr, renal excretion is 60 - 80 %.

Indications

Trimethoprim is primarily indicated in conditions like Benign gastric and duodenal ulceration and chronic gastritis, Prophylaxis of NSAID-induced gastric and duodenal ulceration, Prophylaxis of UTI, Respiratory tract infections, UTI.

Contraindications

Trimethoprim is contraindicated in conditions like Impaired renal function, Haematological disorders.

Dosage

Trimethoprim's dosage details are as follows:

Dose	Single Dose	Frequency	Route	Instructions
Adult Dosage
300 mg	300 mg	Every 24h	PO	For 7-Days
Paediatric Dosage (20kg)
4 mg/kg	4 mg/kg	Every 12h	Oral	-
Neonatal Dosage (3kg)
4 mg/kg	4 mg/kg	Every 12h	Oral

Drug Interactions

Unknown21 interactions

1 interaction

Major1 interaction

Minor1 interaction

Moderate4 interactions

Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.

Side Effects

The signs and symptoms that are produced after acute overdosage of Trimethoprim are Vomiting, Depression , Psychosis , Mania , Facial edema.

Warnings / Precautions

Trimethoprim should be used with caution in patients with kidney disease, any anemia or any drug allergy. Trimethoprim should be used during pregnancy only if clearly needed. Avoid use during lactation.

Available Brands

Click on a strength to view available brands.

Single Ingredient

Susp

40 mg/5ml 80 mg

Tabs

160 mg 300 mg

Multi-Ingredient Combinations

Inj

160 mg

Susp

160 mg/5ml 80 mg/5ml

Susp

40 mg/5ml

Tabs

160 mg 40 mg 400 mg 80 mg

Storage Conditions

Trimethoprim should be stored Tab.

Drug Classification

1.6.2.2.8 — Sulphonamides and trimethoprim