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Stability of trimethoprim-sulfamethoxazole injection in five infusion fluids
Abstract:
The stability of an intravenous dosage form of trimethoprim-sulfamethoxazole (Bactrim; Hoffmann-La Roche) was studied in five i.v. fluids at four dilutions. Trimethoprim-sulfamethoxazole injection was diluted 1:25 v/v, 1:20 v/v, 1:15 v/v and 1:10 v/v in 5% dextrose injection, lactated Ringer's injection, 0.45% sodium chloride injection, 0.9% sodium chloride injection, and 5% dextrose and 0.45% sodium chloride injection in quadruplicate. Solutions were mixed in 150-ml glass containers and stored at 23-25 degrees C; 5-ml samples were withdrawn at 0, 1, 2, 4, 6, 8, 12, and 24 hours and filtered with a 0.22-micron filter. Trimethoprim and sulfamethoxazole concentrations in the filtrates were assayed with high-performance liquid chromatography, and the pH of filtrates was measured. Trimethoprim and sulfamethoxazole were stable for 24 hours in all fluids and at all dilutions with one exception. Trimethoprim concentration fell more than 10% in lactated Ringer's injection at 24 hours because of precipitation in one container. There was no consistent change in pH of solutions. It is concluded that trimethoprim-sulfamethoxazole admixtures are stable in glass containers of the five solutions at the dilutions studied for 12 hours at ambient room temperature.
Insights
Trimethoprim-sulfamethoxazole intravenous solutions demonstrated stability for 24 hours in most IV fluids and dilutions. An exception occurred with lactated Ringer's injection due to precipitation.
Area of Science:
- Pharmaceutical Sciences
- Clinical Pharmacy
- Drug Stability
Background:
- Intravenous trimethoprim-sulfamethoxazole is a critical antibiotic combination.
- Assessing the stability of drug admixtures is essential for safe intravenous administration.
- Understanding drug compatibility with various intravenous fluids prevents therapeutic failures.
Purpose of the Study:
- To evaluate the stability of intravenous trimethoprim-sulfamethoxazole in common intravenous fluids.
- To determine the compatibility of trimethoprim-sulfamethoxazole admixtures at various dilutions.
- To establish recommended storage times for trimethoprim-sulfamethoxazole infusions.
Main Methods:
- Trimethoprim-sulfamethoxazole injection was diluted in five different intravenous fluids at four concentrations.
- Solutions were stored in glass containers at room temperature (23-25°C).
- Drug concentrations and pH were measured using high-performance liquid chromatography and a pH meter at various time points up to 24 hours.
Main Results:
- Trimethoprim-sulfamethoxazole remained stable in most admixtures for 24 hours.
- Precipitation of trimethoprim was observed in lactated Ringer's injection at 24 hours, exceeding a 10% concentration decrease.
- No significant or consistent changes in solution pH were detected.
Conclusions:
- Trimethoprim-sulfamethoxazole admixtures are generally stable in the studied intravenous fluids and dilutions for up to 12 hours at room temperature.
- Caution is advised when using lactated Ringer's injection due to potential precipitation.
- Further studies may be warranted for longer-term stability assessments.