Pharmacology Lecture Notes

Chapter 21: Introduction to Pharmacology

Objectives

• Recognize common definitions and nomenclature associated with pharmacology.
• Recognize the various classifications of drugs.
• Describe the actions, indications, and precautions related to various drugs.

Key Concepts in Pharmacology

• Drug Definition: A chemical substance that produces a biologic response in a living system.
• Intent of Drugs: Aid in diagnosis, treatment, or prevention of disease.
• Pharmacology: Science concerned with the origin, nature, effects, and uses of drugs.

Drug Nomenclature

• Chemical Name
  • Identifies the chemical structure of a drug (e.g., Acetylsalicylic Acid).
• Generic Name
  • Name given when a drug becomes commercially available (e.g., Aspirin).
• Trade Name
  • Name given by a particular manufacturer (e.g., Bayer Aspirin).

Physician's Desk Reference (PDR)

• Commonly known as PDR.
• Annual publication with current product information.
• Available online and in hardbound format.
• Contains accepted uses, side effects, contraindications, biochemical action, drug class, and dosage considerations for FDA-approved drugs.
• Consult a pharmacist if PDR is unavailable.

Drug Classifications and Dosages

• Classification by Chemical Action: Drug Families.
• Classification by Legal Name
  • Legend Drugs: Prescription drugs.
  • Non-Prescription: Over-the-counter drugs.
• Dosage Forms
  • Tablets, Inhalants, Suppositories, Capsules, Solutions, Suspensions, Transdermal Patches, Creams.

Classification by Drug Action

1. Analgesics: Pain relievers.
2. Anesthetics: Induce anesthesia.
3. Anti-anemic Agents
4. Anti-anxiety Agents
5. Anti-arrhythmics
6. Antibiotics
7. Anticholinergics
8. Anticoagulants
9. Antidepressants
10. Antiepileptics

Additional Drug Action Classifications

• Antidiabetic Agents
• Antiemetics
• Antifungal Agents
• Antihistamines
• Antihyperlipidemic Agents
• Antihypertensives
• Antiparkinson Agents
• Antiplatelets
• Antipsychotics

Further Drug Action Classifications

• Antiallergic Agents
• Antiviral Agents
• Benzodiazepine Antagonists
• Bronchodilators
• Cholinesterase Inhibitors
• Coagulants
• Corticosteroids
• Diuretics
• Hormones
• Laxatives
• Hypnotics

Final Drug Action Classifications

• Anti-Alzheimer's Drugs
• Mood Stabilizing Drugs
• Nonsteroidal Anti-inflammatory Drugs (NSAIDs)
• Opioid Antagonist
• Osteoporosis Drugs
• Sedatives
• Stimulants
• Thrombolytics
• Vasoconstrictors
• Vasodilators

Controlled Drug Schedules

• Regulated by the Federal Controlled Substances Act.
• Consists of 5 schedules.
• Indicates drug action and its likelihood of abuse and physical/psychological dependency.

Pharmacokinetics Process

• Absorption
• Distribution
• Metabolism
• Excretion

Drug Absorption

• How drug enters the circulatory system.
• Bioavailability: Amount of drug that reaches systemic circulation.
• Drugs need to be absorbed to begin activity.

Drug Distribution

• Absorption of drug into the body and its travel to the intended site of activity via the circulatory system.
• Affected by several factors.

Drug Metabolism (Biotransformation)

• Altering the drug's chemical structure.
• Mostly occurs in the liver.
• Affected by many factors, including drug interactions.

Drug Excretion

• Primary Route: Kidneys.
• Secondary Routes: Liver and biliary tract, lungs, sweat, saliva, breast milk.

Factors Influencing Drug Action

• Patient Age.
• Health Status.
• Time of Day.
• Emotional State.
• Other Drugs in the Body.
• Genetic Variations.
• Disease State.

Drug Reactions

• Side Effect: Unrelated response due to drug acting on non-target tissues.
• Idiosyncratic Reaction: Uncommon response not including therapeutic effect.
• Anaphylaxis: Severe reaction causing respiratory/cardiovascular collapse.

Sedation Drugs

• Minimal Sedation/Anxiolysis
• Moderate Sedation/Analgesia (Conscious Sedation)
  • Common in select medical imaging procedures.
• Deep Sedation/Analgesia
• General Anesthesia

Conclusion

• Radiologic and imaging science professionals need a basic knowledge of pharmacology.
• PDR is a key reference found in radiology departments.
• Pharmacists should be consulted for drug-related queries.
• Common dosage forms include tablets, capsules, suppositories, solutions, suspensions, and transdermal patches.
• Professionals should be aware of drug actions, precautions, and the factors affecting patient response.
• Post-administration, relevant drug information should be recorded in the patient's chart.