Therapeutic, Toxic and Lethal Ranges
Definition
Plasma concentration ranges that guide interpretation, derived from population studies and case reports. They are guidelines, not absolutes. Tolerance, idiosyncratic response, polypharmacy and post-mortem redistribution can shift the boundaries substantially in any individual case.
- Basis
- Population studies and case reports
- Status
- Guidelines, not absolute cutoffs
- Confounders
- Tolerance, idiosyncratic response, polypharmacy
- Interpretation risk
- Post-mortem redistribution shifts values
Common questions
Why can a lethal concentration be survived by one person but not another?+
Individual tolerance built through chronic use, genetic differences in metabolism, and combined drug effects all shift the effective threshold away from population averages, so a single number cannot fit every case.
How does post-mortem redistribution affect interpretation?+
Concentrations of some drugs, especially basic lipophilic ones, can rise in central blood after death as tissue stores release into circulation, so a post-mortem sample can overstate the true ante-mortem level.
Related terms
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- Phase I Metabolism
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- Phase II Metabolism
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- Post-Mortem Redistribution (PMR)
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- Volume of Distribution (Vd)
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