Drugs of Abuse: Bioavailability of Drugs

Biochemistry of Substances

Week 1

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Objectives

Learn how, in general, drugs affect the body

Learn about how drugs enter and exit the body

Learn about drug schedules, uses and addictive potential



Overview

The following is a useful reference table for identifying drugs, their schedules, modes of ingestion effects and much more. http://www.drugdetection.com/table.html



How Drugs Enter

Absorption (through the skin such as Myoflex cream or transdermal patches, or through mucus membranes such as nose and lips)

Oral: Caffeine, cough syrup, pills Inhalation: fumes, smoke Injection: epidural, vaccinations, allergy

shots



Completion

Which of the following is typically administered through absorption? Birth Control Nicotine Caffeine Pain medication Cocaine



Answers

All of the above drugs except caffeine are regularly administered through absorption.

Although most people believe they “inhale” cocaine when it is snorted, actually it is absorbed through the mucous membranes in the nose



How Drugs Exit Half-Life:

The length of time for half of the substance to be excreted from the body

Routes of Excretion Urine Exhalation Defecation Sweat Saliva Breast Milk (nursing mothers)



Factors Determining Physiological Impact Drug Interactions 1+1=3

Sedative + Sedative Sedative + Stimulant Stimulant + Stimulant Opiate+ Sedative Opiate + Stimulant

Cross-Tolerance tolerance to one drug leads to tolerance of

similar drugs



Factors cont…

Individual Differences Weight/Body Fat Gender Ethnicity Physiological Responsiveness Setting/Expectations



The Nervous System

CNS Consists of the brain, spinal cord and

peripheral nervous system Sympathetic (Has sympathy for you)

Excitatory/Fight or Flight Parasympathetic

Inhibitory/calming/relaxing



Neurons, Synapses

Neurons contain neurotransmitters When a neuron in stimulated an action potential

moves to the end and triggers a series of chemical changes

Calcium Ions flow into the neuron causing the release of the neurotransmitter into the space between 2 neurons (synaptic space)

The neurotransmitter molecule then binds, like a lock and key, with the receptor on the other neuron which causes a characteristic reaction



How drugs affect neurotransmission

Increase the amount of the neurotransmitter released

By blocking the postsynaptic receptors

In a few minutes you will be directed to a website that illustrates these points.



Neurochemicals and Hormones

Acetylcholine Norepinepherine Dopamine Endorphins GABA Serotonin



Online Reading

Tutorial on How Drugs Affect the Brain

Go to the website and review the 5 lessons. They are relatively short



Drug Types Stimulants

(After you read the first page, the “next” button is located at the bottom of the page)

Depressants (includes Anxiolytics) Inhalants Benzodiazepines Barbiturates Alcohol

Opiates Hallucinogens Marijuana Steroids



Drugs and Athletic Performance

Overview

Some psychoactive drugs have actual performance-enhancing side effects. However, many actually decrease performance, primarily because of adverse cardiovascular effects and impaired coordination and judgment. Athletes and nonathletes alike may be knowingly or unknowingly exposed to psychoactive substances if they use over-the-counter, recreational, or prescription drugs.



Drug Schedules (Web Link)

Schedule I High potential for abuse. No medical uses Heroin, LSD, PCP

Schedule II High potential for abuse. Some medical uses Codeine, morphine, methadone, amphetamines

Schedule III Some potential for abuse. Some medical uses Codeine cough syrups, long acting barbiturates, No

Refills allowed



Schedules cont…

Schedule IV Low Potential for abuse. Many medical

uses, Some limits on refills Antianxiety drugs

Schedule V Low potential for abuse, Many uses. No

limits on prescription refills

Health & Medicine

Drugs of Abuse: Bioavailability of Drugs