Therapeutic window, steady state, washout — and tolerance
Turns half-life into practical rules: how long until a daily medicine works steadily, how long until it's gone, and why stopping can cause withdrawal.
Where this fitsConnects to 1 · Unlocks 2
- Connects to
- Half-life and redistribution — Everything here is counted in half-lives.
- Unlocks
- Norepinephrine and serotonin — and serotonin syndrome — Washout periods prevent serotonin syndrome when switching drugs.
- Glutamate and GABA: the brain's accelerator and brake — Withdrawal from depressants is rebound excitation.
Orient
Therapeutic window – the blood concentration should stay between a level that is too high and too low. Steady state – point of balance at which the rate of drug absorption approximates the rate of excretion, reached after ~6x the half-life. Washout period – the drug is not fully out of your system once you stop taking it. Tolerance – state of progressively decreasing responsiveness to the same dose of a drug.
Course terms
Your professor's wording, word for word from the slides. Learn the term and this definition — the explanation underneath is only there to help it make sense.
- Therapeutic window
“Drugs should be given in such a way that the blood concentration stays between a level that is too high and too low”Slides 04, p. 46
Too low: no benefit. Too high: no better effect, more side effects.
- Steady state
“Point of balance at which the rate of drug absorption approximates the rate of excretion”Slides 04, p. 47
“Time to reach steady-state concentration = ~6x the half-life, independent of actual drug dosage.”
- Washout period
“Washout period – the drug is not fully out of your system once you stop taking it!”Slides 04, p. 49
~5 half-lives, 6 to be more careful — and account for active metabolites.
- Tolerance
“Tolerance - state of progressively decreasing responsiveness to the same dose of a drug”Slides 04, p. 50
Three kinds: metabolic, cellular-adaptive, behavioral conditioning.
- Withdrawals
“Withdrawals – opposite effects of the drug itself”Slides 04, p. 50
Physical dependence follows tolerance.
- Abstinence (discontinuation) syndrome
“Abstinence (discontinuation) syndrome aka drug withdrawals…kinda”Slides 04, p. 50
Withdrawal after stopping a drug; mitigate with tapering and longer washouts.
From your course: Course slides 04, pp. 46–50
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Full lesson: Therapeutic window, steady state and washout · Tolerance, dependence and discontinuation