Psychopharmacology: Pharmacokinetics (PDF)

PSYCHOPHARMACOLOGY  PSYCHOPHARMACOLOGY Objectives Compare how routes of administration affect the speed of drug distribution in the body Distinguish the concepts affinity and efficacy For each of the neurotransmitters reviewed: Give an example of a function it is involved in...

PSYCHOPHARMACOLOGY  PSYCHOPHARMACOLOGY Objectives Compare how routes of administration affect the speed of drug distribution in the body Distinguish the concepts affinity and efficacy For each of the neurotransmitters reviewed: Give an example of a function it is involved in Recognize how it is created (synthesized) Recognize agonists and antagonists for its receptors  PSYCHOPHARMACOLOGY: TERMS Terms to help navigate the world of your brain on drugs Pharmacokinetics – ‘movement’ of drug in body (in, around, and out…) – Processes by which drugs are absorbed, distributed within the body, metabolized, and excreted over time VS Pharmacodynamics – Once absorbed, the effects of drug on the body – These effects come about through drug actions at receptors  PSYCHOPHARMACOLOGY: KINETICS Pharmacokinetics – Processes by which drugs are absorbed, distributed within the body, metabolized, and excreted over time 1. Method of administration affects: – How much drug reaches a given site in the body – How quickly a drug can start acting at receptors enteral parenteral  ROUTES OF ADMINISTRATION: ENTERAL “first pass” metabolism Slow absorption Final concentration is less predictable  ROUTES OF ADMINISTRATION Enteral (PO)  KINETICS: ABSORPTION AND DISTRIBUTION Factors affecting drug penetration of CNS Lipid solubility – Lipid-soluble molecules pass easily through cells making up blood vessel walls – Rapid distribution throughout brain tissue – Blood–brain barrier (BBB) is a barrier only for water-soluble molecules A few sites in BBB where passage is easier for water-soluble molecules  KINETICS: METABOLISM AND EXCRETION Drugs do not remain in body indefinitely; metabolized by enzymes Metabolites of drugs are excreted via several routes – Urine – Feces – Sweat – Breast milk – Exhaled air  KINETICS: METABOLISM AND EXCRETION Brain also contains enzymes that metabolize drugs – Some at synaptic cleft – Some found inside neurons, glia Metabolites of drugs are not necessarily inactive Can themselves have effects, sometimes powerful ones – e.g., monoamine oxidases (MAOs) ‘frozen addicts’ story from your textbook; MPTPMPP+ via MAO-B