Pharmacology: Basic Concepts

Introduction to Pharmacology

• Pharmacology is the study of drugs, their bodily effects, and their use in medical treatments.
• Pharmacokinetics involves the body's drug processing through absorption, distribution, metabolism, and excretion.
• Pharmacodynamics details how drugs affect the body through their mechanisms of action.
• Half-life is the time drugs take to reduce by half in the body.
• Therapeutic index measures the range between effective and toxic drug doses.

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

• Absorption is the process of a drug entering the bloodstream.
• The route of administration affects absorption rate; IV is the fastest, while oral is slower.
• Absorption is affected by food, pH levels, blood flow, and lipid solubility.
• Distribution is how drugs move throughout the body.
• Protein-binding affects distribution, with highly protein-bound drugs like warfarin increasing toxicity risks.
• Metabolism is the breakdown of drugs, primarily occurring in the liver via CYP450 enzymes.
• First-pass effect involves oral drugs undergoing liver metabolism before reaching circulation.
• Excretion is how drugs leave the body.
• Kidneys are the main organ for drug excretion.
• Renal impairment necessitates dose adjustments.

Medication Administration and Safety

• The "10 Rights" guide safe medication administration practices:
• Right Patient: Correct patient verification
• Right Drug: Ensuring the correct medication
• Right Dose: Administering the accurate dosage
• Right Route: Choosing the appropriate administration method
• Right Time: Giving medication at the prescribed time
• Right Documentation: Accurately recording medication administration
• Right Reason: Understanding the purpose of the medication
• Right Response: Monitoring for the intended response
• Right Education: Providing patient education about the drug
• Right To Refuse: Respecting the patient's right to decline medication
• High-risk medications (APINCH) require extra caution during administration:
• Anti-infectives
• Potassium (KCl)
• Insulin
• Narcotics (opioids)
• Chemotherapy
• Heparin (anticoagulants)

Autonomic Nervous System Drugs

• The sympathetic nervous system (SNS) triggers the "fight or flight" response.
• Epinephrine/Norepinephrine are the neurotransmitters involved in the SNS.
• Adrenergic agonists stimulate the SNS; for example, Epinephrine and Albuterol, are for asthma, anaphylaxis, and shock.
• Adrenergic blockers (Beta-blockers) inhibit the SNS.
• Metoprolol and Propranolol treat hypertension, angina, and heart failure.
• Nursing considerations include monitoring heart rate and blood pressure, and avoiding abrupt cessation of the drugs.

Cardiovascular Drugs

• Diuretics remove excess fluid and treat hypertension and heart failure.
• Loop diuretics (Furosemide) require potassium level monitoring.
• Thiazide diuretics (Hydrochlorothiazide) serve as a first-line treatment for hypertension.
• Potassium-sparing diuretics (Spironolactone) require avoiding high-potassium foods.
• ACE Inhibitors (-pril) like Lisinopril and Enalapril, are used for hypertension and heart failure.
• ACE Inhibitors side include dry cough, hyperkalemia, and angioedema.

Antibiotics Overview

• Penicillins (Amoxicillin) require allergy checks due to the risk of rash and anaphylaxis.
• Cephalosporins (Cephalexin, Ceftriaxone) exhibit cross-allergy with penicillins.
• Macrolides (Azithromycin, Erythromycin) can cause QT prolongation.

Endocrine Drugs

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

The Big 5 Medication Categories

• This includes Antihypertensives, Antibiotics, Diuretics, Anticoagulants & Antiplatelets, and Diabetes Medications.

Antihypertensives (Lower Blood Pressure)

• ACE Inhibitors (-pril) like Lisinopril and Enalapril can cause dry cough, hyperkalemia, and angioedema.
• Beta-Blockers (-lol) like Metoprolol and Propranolol may cause bradycardia and fatigue, and should be avoided in asthma.
• Calcium Channel Blockers (-dipine) like Amlodipine and Diltiazem may cause edema, constipation, and hypotension.
• ARBs (-sartan) like Losartan and Valsartan can cause hyperkalemia.
• Diuretics are also used for hypertension and are covered in a separate section.
• Nursing considerations include checking blood pressure and heart rate before giving medication
• Watch for dizziness and hypotension.
• Hold if systolic blood pressure is below 100 mmHg.

Antibiotics (Fights Infections)

• Penicillins (-cillin) like Amoxicillin can cause allergies, rash, and anaphylaxis.
• Cephalosporins (Cef-) like Ceftriaxone have cross-allergy with penicillins.
• Macrolides (-mycin) like Azithromycin can cause QT prolongation.
• Aminoglycosides (-mycin, but NOT azithromycin) like Gentamicin can cause ototoxicity and nephrotoxicity.
• Fluoroquinolones (-floxacin) like Ciprofloxacin pose a risk for tendon rupture.
• Sulfonamides (Sulfa drugs) like Trimethoprim/Sulfamethoxazole (Bactrim) can cause allergy and photosensitivity.
• Nursing considerations include completing the full course of antibiotics
• Watch for superinfections (C. diff, yeast infections)
• Avoid alcohol with some antibiotics such as Metronidazole.

Diuretics (Reduce Fluid & Blood Pressure)

• Loop Diuretics like Furosemide (Lasix) can cause hypokalemia and ototoxicity.
• Thiazide Diuretics like Hydrochlorothiazide (HCTZ) are first-line for hypertension.
• Potassium-Sparing Diuretics like Spironolactone pose a risk for hyperkalemia.
• Nursing considerations for diuretics include monitoring electrolytes (especially potassium & sodium)
• Give in the morning to prevent nighttime urination.
• Watch for dizziness, dehydration, and low blood pressure.

Question and Answer

• An intramuscular (IM) injection should be administered at a 90-degree angle.
• For a 5,000-unit subcutaneous heparin injection from a 10,000 units/mL vial, draw up 0.5 mL.
• Immediately dispose of the needle in a sharps container after administering an injection.
• When mixing insulin, draw up Regular (clear) insulin first, then NPH (cloudy) insulin.
• Use a 1 mL tuberculin syringe, a 26-27G needle, and a 5-15-degree angle when administering a TB test.