Pharmacodynamics: Agonists & Antagonists

Pharmac

'odynamics

• Agonists: Drugs mimicking receptor activity, e.g., morphine activates receptors for analgesia and sedation.
• Antagonists: Drugs blocking receptor activity, e.g., Losartan inhibits angiotensin II receptors, preventing vasoconstriction.
• Nonspecific Drug Effects: Can either be beneficial or adverse, impacting unintended tissues or organs.
• Epinephrine: Exhibits effects on multiple receptors (Alpha1, Beta1, Beta2).

Therapeutic Index

• Definition: Measures the safety margin of a drug by comparing effective doses to lethal doses.
• Low Therapeutic Index: Indicates narrower safety margins, requiring close monitoring.
• High Therapeutic Index: Indicates wider safety margins and reduced risk of toxicity.

Nursing Process

• Assessment: Evaluate cultural background and unconventional therapeutic practices.
• Planning: Work with patients to reduce high-risk health behaviors.
• Interventions: Merge nonharmful traditional practices with biomedical prescriptions.
• Patient Teaching: Engage family in education regarding therapies.
• Evaluation: Ensure patient understands prescribed therapies.

Drug Interactions

• Altered Effects: Interaction with other drugs can modify a drug's action.
• Adverse Drug Reactions: Range from mild to severe, including hypersensitivity and anaphylaxis.
• Drug-Incompatibility: Chemical interactions occurring outside the body (e.g., in syringes or IV bags).
• Additive Effects: Similar drugs combined for therapeutic benefits while minimizing side effects.
• Synergistic Effects: Combined drug effects exceed the sum of individual effects.
• Antagonistic Effects: One drug stops the action of another.

Drug-Food Interactions

• Impact on Absorption: Foods can alter drug absorption rates; grapefruit juice with statins can increase side effects.

Over-the-Counter (OTC) Drugs

• Categories:
  • Category I: Safe and effective
  • Category II: Unsafe and ineffective
  • Category III: Insufficient data
• Cautions: OTC use may mask symptoms, delay professional diagnosis, and increase overdose risk; careful label reading is essential.

Herbal Therapies

• Definition: Plant-based products used for scent, flavor, or therapeutic properties (e.g., Ginkgo biloba).
• Regulations: Dietary Supplement Health and Education Act (1994) ensures safety and labeling.
• Risks: Increased reaction risk when combined with prescription or OTC medications.

Geriatric Pharmacology

• Polypharmacy: Common in the aging population, increasing medication use.
• Physiologic Changes: Age leads to reduced water and body mass, impacting drug distribution and metabolism.
• Adverse Reactions: Risk of unintended harmful responses, particularly with altered kidney and liver functions.

Substance Use Disorders

• Types:
  • Alcohol use disorder: Treatable with inpatient care and drug-assisted treatments.
  • Tobacco use disorder: Treated with cognitive behavioral therapy and medications like nicotine replacement and others.
  • Cannabis use disorder: Has psychoactive effects with limited benefits.
• Stimulant Use: Nicotine is highly addictive with numerous cardiovascular and CNS side effects.

Nicotine Dependency

• Withdrawal: Symptoms can start within hours of cessation, peaking at 1-2 days, and can last for weeks to months.

Explore the concepts of pharmacodynamics focusing on receptor theory, including the roles of agonists and antagonists in drug activity. Understand how drugs like morphine interact with receptors to elicit various responses. This quiz tests your knowledge on drug mechanisms and their effects on the body.