PubMed · 7457355
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1980. Controlled substances: uses & effects.. https://pubmed.ncbi.nlm.nih.gov/7457355/
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This article presents the first known practical method to apply one-compartment pharmacokinetic modeling to prediction of doses for drugs from one or more blood-drug concentrations, without requiring approximations or a computer. It should be useful for regulating doses of orally administered CNS drugs whose effects develop over a day or more, e.g., lithium, antidepressants, and anticonvulsants. Pharmacokinetic calculations for sequences of one, two, and three test doses are condensed into graphs that can be rapidly applied for clinical purposes. These graphs account for dose division, blood sampling time, and drug elimination rate; they show that the ratio of the steady-state day-mean drug level to the test-drug blood level is independent of the half-life if the test level is about a day after the last test dose. The calculations show the same value as experimental measurements for the ratio between steady-state serum lithium level and serum lithium level measured after a test dose. A rational strategy for drug-loading doses is discussed.
An external quality assessment survey of testing facilities in UK clinical laboratories for the detection of drugs of abuse was made with nine freeze-dried samples of urine containing representative drugs with their metabolites from the following seven classes; amphetamines and stimulants, barbiturates, cannabinoids, cocaine, minor tranquillisers, opiates and non-opiate narcotics. Reports were received from 120 laboratories. Thirty six per cent of laboratories reported on all seven drug classes and 71% on the five classes excluding cannabinoids and cocaine. A single drug screening technique was used by 32% of laboratories whilst 46% were able to perform tests by both immunological and chromatographic techniques. There was a mean level of false positive reporting of 4.3% and an observed level of false negative reports of 8.4%, the latter underestimating the true frequency. The minor tranquillisers, cocaine and benzoyl ecgonine were the most frequently missed analytes. Several false reports had important potential implications for patient care.