TY - JOUR T1 - When is it useful to know the plasma concentration of drugs? JF - Drug and Therapeutics Bulletin JO - Drug Ther Bull SP - 37 LP - 39 DO - 10.1136/dtb.9.10.37 VL - 9 IS - 10 A2 - , Y1 - 1971/05/07 UR - http://dtb.bmj.com/content/9/10/37.abstract N2 - It is possible to measure the plasma concentration of a large variety of drugs, either by chemical analysis, where estimation can take less than an hour, as with barbiturates, or by biological assay, as with antibiotics, in which case the estimation may take several days. ER -