PSY 383 - Week 1

Drug

A medicine or other substance which has a physiological effect when ingested or otherwise introduced into the body

Psychoactive Drug

a medicine or other substance which affects the mind through the physiological effect of the drug acting in the brain

Receptor

Agonist

Antagonist

Does Response

Drug Distribution through Circulation

Heart pumps blood through out the body completing a cycle aprroximately every minute. Drugs abosrbed into the capillaries are distributed by the heart moving blood through the capillaries.

solubility greatly affects distribution. Binding of drugs to proteins in blood plasma may be unable to leave the veins and enter arterial circulation

Drug Metabolism

Tolerance

Metabolic Tolerance

Behavioral Tolerance

Receptor Tolerance

Sensitization

Withdrawal

Pharmacology

Neuropharmacology

How drugs work in the brain

Pharmacokinetics

How drugs get into and move through the body
Affects:

• Onset - when drug starts acting

• Strength - how strongly drug acts (dosage by time)

• Duration - how long the effects of the drug lasts

Absorption

Refers to processes and mechanisms by which drugs pass from the external world into the bloodstream. Inhalation, injection, snorting/snuffing, ingestion.

Distribution

Drug dispersment through body tissues. Drug is distributed to all tissues, but not all tissues have receptors for drugs

Metabolism

Elimination

The process of drugs leabing the body inclduign the kidneys, lungs, bile, and skin. The major route of drug elimination form the body is renal excretion of drug metabolties following the hepatic biodegration of the drug into drug metobolites (larer, water-soluble, biologically inactive metobolically tranformed drug molecules)

Tolerance

Dependence

Dosage

Receptors

Oral Drug Admin (Gastrointenstinal)

Drug must surivve ezymatic digestion through the stomach. Remaining drug is absorbed through capillaries in the villi of the small intestine.

Rectal Administation

Administed in suppository form often if patient is vomitting or cannopt swallow. Absorption can be irregular, unpredicable, or incomplete, and irritate the mebrane

Injection

Administration of a drug intervenously, subcutaneously, or intramuscularly to enable the absorption of the susbtance into the blood stream. Produces a prompt response and enables more accurate doseage due to predicable absorption.

Intravenous Injection

Administration of a drug directly into a vein. Drug is introduced directly into the blood stream; circumvents absorption. Can administer large volumes of dilute drugs which might otheriwse be irritants at high concentration

Intramuscular Injection

Administration of a drug directly into a muscle. Enables slow and sustained action of drug.

Subcutaneous Injection

Administration of a drug just under the skin. Enables slow and sustained action of drug. Some insoluble suspensions

Inhalation Administation (insufflation)

Administration of a drug through the vascular/capillary tissue of the lungs. Smoking, vaping, inhalers. Often faster than injection.

Lungs have large surface area and lots of blood exchange. Additionally lung cappilaries are carried in the pulmonary viens directly to the arterial side of the heart and directly into the brain

Transdermal Administration

Drugs administerted through patches, lotions, cremas, etc. placed on the skin and absorbed into the blood stream.

Mucous Membrane Administration

Drug administered through membrane of the mouth or nose.

Lipid Soluble

Dissovable in fat (nonionized)

Water Soluble

Dissolvable in water (ionized)

Side Effects

Capillaries

tiny, cylindrical blood vessels with walls formed by a thin, single cell layer. Between cells pores enable the passage of small molecules to the blood. Drug molecules will pass into capillaries until they are at equilibrium with the surrounding tissue

Membranes

Blood Brain Barrier

A structual barrier which maintains the protective envrionemnt the brain eneds ot function normally. Invloves specialize cells which affect nearly all capillaries in the brain such they do not have pores and are instead tightly bound together are covered in a fatty barrier, the glial sheath.

Thus inorder for a srug to enter the brain it must pass through the sheath and through the capillary walls meaning it must be highly lipid soluble

Placental Barrier

Placental membranes must separte two distinct humans with differing genetic compositions. The separation of fetal blood from maternal blood are only permeable to passive diffustion, i.e. fat-soluble sustances.

This means, generally, any psychoactive drug will be present in the fetus at a concnetration quite similar to that in the mother’s bloodstream

Metabolites

Excretion

Circulatory Half Life

Relates to the time it takes for a drug to be distributed through the body to reach half of its blood plasma concentration.

Elimination Half Life

The amount of time from the drug concentration to decrease by 50% in the blood

Metabolic Tolerance

Pharmacodynamic Tolerance (receptors)

Behavioral Tolerance

Homeostatis

Physical Dependence

Withdrawal

Addiction

Pharmacodynamics

How a drug acts on the body through receptors. Psychoactive drug action on brain receptors. Neurons and brain systems

Receptors

Drug-receptor Binding

Dose-response curves

Potency

Drug Safety and Effectiveness

ED50

LD50

Therapeutic Index

Drug Interactions

Toxicity

Placebo