Сульфаметоксазол

Описание

Like sulfisoxazole, this drug is effective in treating infections caused by streptococci, gonococci, pneumococci, staphylococci as well as colon bacillus. Unlike sulfisoxazole, only about 70% of it binds with proteins in the plasma after oral administration, and it diffuses mostly to tissues and tissue fluids. However, since it is removed much slower than sulfisoxazole, it does not require frequent administration and is also the drug of choice for many systemic infections. Moreover, it is an ingredient of a combined drug named bactrim, biseptol, and so on (which will be examined later on), which has a fixed correlation with trimethoprim. Synonyms of this drug are gantanol, sinomin, sulfisomezole, and others.

Химические свойства

solid

Определение

ChEBI: An isoxazole (1,2-oxazole) compound having a methyl substituent at the 5-position and a 4-aminobenzenesulfonamido group at the 3-position.

Антимикробная активность

The intrinsic activity is similar to that of sulfadiazine.

Общее описание

Sulfamethoxazole’s plasma half-life is 11 hours. Sulfamethoxazole is a sulfonamide drug closely relatedto sulfisoxazole in chemical structure and antimicrobial activity.It occurs as a tasteless, odorless, almost white crystallinepowder. The solubility of sulfamethoxazole in the pHrange of 5.5 to 7.4 is slightly lower than that of sulfisoxazole but higher than that of sulfadiazine, sulfamerazine, or sulfamethazine.Following oral administration, sulfamethoxazole is notabsorbed as completely or as rapidly as sulfisoxazole, andits peak blood level is only about 50% as high.

Реакции воздуха и воды

Insoluble in water.

Пожароопасность

Flash point data for Sulfamethoxazole are not available but Sulfamethoxazole is probably non-flammable.

Фармацевтические приложения

This is the sulfonamide component of co-trimoxazole. It is slightly soluble in water.

Фармакокине?тика

Oral absorption： 85%
C_max 800 mg oral： c.50 mg/L after 3–6 h
Plasma half-life： 6–20 h
Volume of distribution： 12–18 L
Plasma protein binding： 65%
Penetration of extravascular sites, including the CSF, is good. It crosses the placenta and achieves levels in breast milk of about 10% of the simultaneous plasma concentration. It is extensively metabolized, but about 30% of the dose is excreted unchanged in urine so that high concentrations are achieved.

Клиническое использование

Sulfamethoxazole is used only in combination with the diaminopyrimidine trimethoprim.

Побочные эффекты

Unwanted effects are those common to sulfonamides. In addition, benign intracranial hypertension has been reported in children. Most side effects of co-trimoxazole are thought to be attributable to the sulfonamide component.

Профиль безопасности

Moderately toxic by ingestion and intraperitoneal routes. Questionable carcinogen with experimental tumorigenic data. When heated to decomposition it emits very toxic fumes of NOx and SOx.