abstinence syndrome action absorption active metabolite adjunctive adverse effect affinity agonist antagonist association augmentation autoreceptor bimodal bind bioavailability biotransformation chemical class cigarette clinical class cholinergic hypothesis of Alzheimer's disease Cmax Cmin combination combination pharmacotherapy compliance controlled substances schedule cross taper cross titration delivery depot discontinuation syndrome dissociation distomer distribution dosage form dose downregulation drug holiday EC50 ED50 effect effective concentration 50% effectiveness efficacy elimination enantiomer eutomer first order kinetics generic half life heteroreceptor hydrophilicity IC50 idiosyncratic response immediate release inactive metabolite indication inhibitory concentration 50% interaction inverse agonist isomer joint LD50 ligand lipid solubility lipophilicity loading dose loose blockade maintenance dose median inhibitory concentration metabolite mixed agonist/antagonist monotherapy neurotransmitter off-label optical isomer orphan drug overlap and taper parenteral partial agonist pharmacodynamics pharmacokinetics pharmacologist placebo polypharmacy potency potentiation precursor priming dose prodrug psychopharmacology racemic receptor receptor reserve recipe reuptake reverse tolerance route of administration Rx schedule selectivity side effect spare receptors stereoisomer switching tachyphylaxis TD50 therapeutic effect therapeutic index therapeutic window tight blockade tincture titration tolerability tolerance toxicometrics trimodal unimodal upregulation volume of distribution zero order kinetics