Pharmacology: Basic Principles

Introduction to Pharmacology

• Pharmacology studies drugs, their effects, and their use in medical treatments.
• Pharmacokinetics explains how the body processes drugs through absorption, distribution, metabolism, and excretion.
• Pharmacodynamics explains how drugs affect the body, referring to the mechanism of action.
• Half-life refers to the time it takes for a drug concentration to reduce by half in the body.
• Therapeutic index is the ratio between a drug's effective dose and toxic dose.

Drug Absorption, Distribution, Metabolism, and Excretion (ADME)

• Absorption is the process by which a drug enters the bloodstream.
• The route of administration affects absorption; IV is the fastest, while oral is slower.
• Absorption is affected by food, pH, blood flow, and lipid solubility.
• Distribution is how a drug moves through the body.
• Protein-binding affects distribution; high protein-bound drugs (e.g., warfarin) carry higher toxicity risks.
• Metabolism is the process of how a drug is broken down.
• The liver is the primary site of metabolism, using CYP450 enzymes.
• First-pass effect is when oral drugs undergo liver metabolism before reaching circulation.
• Excretion is how a drug leaves the body.
• The kidneys are the main organ for drug excretion.
• Patients with renal impairment require dose adjustments.

Medication Administration and Safety

• The 10 Rights of Medication Administration include:
  • Right Patient
  • Right Drug
  • Right Dose
  • Right Route
  • Right Time
  • Right Documentation
  • Right Reason
  • Right Response
  • Right Education
  • Right to Refuse
• High-risk medications (APINCH) include:
  • Anti-infectives
  • Potassium (KCl)
  • Insulin
  • Narcotics (opioids)
  • Chemotherapy
  • Heparin (anticoagulants)

Autonomic Nervous System Drugs

• The Sympathetic Nervous System (SNS) is responsible for "Fight or Flight" responses.
• Epinephrine/Norepinephrine is the neurotransmitter.
• Adrenergic Agonists stimulate the SNS, for an example Epinephrine, Albuterol.
  • Used for asthma, anaphylaxis, and shock.
• Adrenergic Blockers (Beta-blockers) inhibit the SNS, for example Metoprolol, Propranolol.
  • Used for treating hypertension, angina, and heart failure.
• Monitor HR & BP and don't stop administering abruptly as a nursing consideration.

Cardiovascular Drugs

• Diuretics remove excess fluid and are used for hypertension (HTN) and heart failure.
• Loop diuretics (Furosemide) require monitoring of potassium levels.
• Thiazide diuretics (Hydrochlorothiazide) are first-line treatment for hypertension.
• Potassium-sparing diuretics (Spironolactone) require avoiding high-potassium foods.
• ACE Inhibitors (-pril) examples are Lisinopril, Enalapril.
  • Used for HTN and heart failure.
  • Side effects include dry cough, hyperkalemia, and angioedema.

Antibiotics Overview

• Penicillins (Amoxicillin) require checking for allergies, as they can cause rash and anaphylaxis.
• Cephalosporins (Cephalexin, Ceftriaxone) carry a cross-allergy risk with penicillins.
• Macrolides (Azithromycin, Erythromycin) can cause QT prolongation.

Endocrine Drugs

• Diabetes medications include various types of insulin.
• Rapid-acting insulin (Lispro, Aspart) has an onset of 15 minutes and peaks in 1 hour.
• Short-acting insulin (Regular) has an onset of 30 minutes and peaks in 2-3 hours.
• Intermediate insulin (NPH) has an onset of 2 hours and peaks in 6-8 hours.
• Long-acting insulin (Glargine, Detemir) has no peak.

The Big 5 Medication Categories

• Antihypertensives treat blood pressure.
• Antibiotics fight infections.
• Diuretics regulate fluid and blood pressure.
• Anticoagulants & Antiplatelets are blood thinners.
• Diabetes Medications control blood sugar.

Antihypertensives (Lower Blood Pressure)

• Common classes include ACE Inhibitors (-pril) like Lisinopril, Enalapril.
  • Side effects: dry cough, hyperkalemia, angioedema
• Beta-Blockers (-lol) like Metoprolol, Propranolol.
  • Side effects: bradycardia, fatigue, avoid in asthma
• Calcium Channel Blockers (-dipine) like Amlodipine, Diltiazem.
  • Side effects: edema, constipation, hypotension
• ARBs (-sartan) such as Losartan, Valsartan.
  • Side effects: no cough, risk for hyperkalemia
• Check BP and HR before giving, watch for dizziness and hypotension, and hold if systolic BP