Name: Trimethoprim
Brand: Selleck Chemicals
SKU: S3129
Availability: InStock
Rating: 5 (3 reviews)

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Quality Control

Batch: Purity: 99.96%

99.96

Related Targets	Integrase Antibiotics Anti-infection Fungal Antiviral COVID-19 Parasite Reverse Transcriptase HIV HCV Protease
Other Bacterial Inhibitors	BTZ043 Racemate Teicoplanin Pefloxacin Mesylate Ceftiofur Solithromycin 6-Methoxydihydrosanguinarine Proanthocyanidins Flagelin 22 Taurolidine Skatole

Solubility

In vitro
Batch:

DMSO : 58 mg/mL (199.77 mM)
(Moisture-contaminated DMSO may reduce solubility. Use fresh, anhydrous DMSO.)

Water : Insoluble

Ethanol : Insoluble

Molarity Calculator

Mass	Concentration	Volume	Molecular Weight
Mass value Mass unit	Concentration value Concentration unit	Volume value Volume unit	Molecular weight (g/mol)

Dilution Calculator Molecular Weight Calculator

In vivo batch selection In vivo Batch:
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Clear solution	5%DMSO 1 40%PEG300 2 5%Tween80 3 50%ddH2O Validated by Selleck labs. Should you need adjustments to this formulation, contact our sales team for custom testing.	2.900mg/ml (9.99mM)	Taking the 1 mL working solution as an example, add 50 μL of 58 mg/ml clarified DMSO stock solution to 400 μL of PEG300, mix evenly to clarify it; add 50 μL of Tween80 to the above system, mix evenly to clarify; then continue to add 500 μL of ddH2O to adjust the volume to 1 mL. The mixed solution should be used immediately for optimal results.
Clear solution	5% DMSO 1 95% Corn oil Validated by Selleck labs. Should you need adjustments to this formulation, contact our sales team for custom testing.	0.725mg/ml (2.50mM)	Taking the 1 mL working solution as an example, add 50 μL of 14.5 mg/ml clear DMSO stock solution to 950 μL of corn oil and mix evenly. The mixed solution should be used immediately for optimal results.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.

In vivo Formulation Calculator (Clear solution)

Step 1: Enter information below (Recommended: An additional animal making an allowance for loss during the experiment)

Dosage: mg/kg

Average weight of animals: g

Dosing volume per animal: μL

Number of animals:

Step 2: Enter the in vivo formulation (This is only the calculator, not formulation. Please contact us first if there is no in vivo formulation at the solubility Section.)

% DMSO

%

% Tween 80

% ddH₂O

% DMSO

+

%

Calculation results:

Working concentration: mg/ml;

Method for preparing DMSO master liquid: mg drug pre-dissolved in μL DMSO ( Master liquid concentration mg/mL, Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug. )

Method for preparing in vivo formulation: Take μL DMSO master liquid, next addμL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH₂O, mix and clarify.

Method for preparing in vivo formulation: Take μL DMSO master liquid, next add μL Corn oil, mix and clarify.

Note: 1. Please make sure the liquid is clear before adding the next solvent.
2. Be sure to add the solvent(s) in order. You must ensure that the solution obtained, in the previous addition, is a clear solution before proceeding to add the next solvent. Physical methods such
as vortex, ultrasound or hot water bath can be used to aid dissolving.

Chemical Information, Storage & Stability

Molecular Weight	290.32	Formula	C₁₄H₁₈N₄O₃	Storage (From the date of receipt)	3 years-20°Cpowder
CAS No.	738-70-5	Download SDF		Storage of Stock Solutions	1 year-80°Cin solvent 1 month-20°Cin solvent
Synonyms	BW 56-72, NIH 204, NSC-106568			SMILES	COC1=CC(=CC(=C1OC)OC)CC2=CN=C(N=C2N)N

Read more about storage stability stock solution CAS number SMILES

Mechanism of Action

In vitro	Trimethoprim acts by interfering with the action of bacterial dihydrofolate reductase, inhibiting synthesis of tetrahydrofolic acid. The Inhibition starves the bacteria of nucleotides necessary for DNA replication causing, in certain circumstances, cell lethality due to thymineless death.
References	[1] https://pubmed.ncbi.nlm.nih.gov/21741802/ [2] https://pubmed.ncbi.nlm.nih.gov/8920632/

Clinical Trial Information

(data from https://clinicaltrials.gov, updated on 2026-03-20)

NCT Number	Recruitment	Conditions	Sponsor/Collaborators	Start Date	Phases
NCT07485010	NOT_YET_RECRUITING	Mycobacterium Abscessus Pulmonary Disease; Mycobacterium Abscessus Infection; Non-Tuberculous Mycobacterial (NTM) Infections; Non-Tuberculous Mycobacteria Pulmonary Disease	The University of Queensland	2027-04	PHASE2
NCT04851015	RECRUITING	Pneumocystis; Pneumocystis Pneumonia; Pneumocystis Jirovecii Infection; Pneumocystis Infections; Pneumocystis Carinii Infection; Pneumocystosis; Pneumonia (Etiology); Pneumocystis Carinii; Infection, Resulting From HIV Disease; Pneumocystosis Associated With AIDS	Todd C. Lee MD MPH FIDSA	2025-11-28	PHASE3
NCT07665359	NOT_YET_RECRUITING	Chronic Obstructive Pulmonary Disease (COPD)	Second Affiliated Hospital, Zhejiang University, School of Medicine	2026-07-01
NCT07106125	NOT_YET_RECRUITING	Kidney Transplant; Urinary Tract Infection(UTI); Antibiotic Prophylaxis; Remote Patient Monitoring; Feasibility Pilot Study	University of California, San Francisco	2026-11	PHASE4
NCT07619027	NOT_YET_RECRUITING	Pneumocystis Jirovecii Pneumonia; Kidney Transplantation	Anhui Provincial Hospital	2026-06	PHASE4
NCT05268120	RECRUITING	MRSA	Leiden University Medical Center	2022-07-25

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Handling Instructions

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Trimethoprim Bacterial chemical

Chemical Structure

Molecular Weight: 290.32