General Pharmacology Flashcards

Antibiotics

• Penicillins:
  • Inhibit cell wall synthesis (bactericidal).
  • Effective against gram-positive bacteria and anaerobes; Penicillin G treats syphilis and strep A.
  • Adverse effects: Hypersensitivity, hematological reactions, GI issues, CNS toxicity.
• Cephalosporins:
  • Similar to penicillins, fewer side effects; inhibit cell wall synthesis (bactericidal).
  • Generations vary in coverage: 1st (gram-positive), 2nd (some gram-negative), 3rd (most gram-negative), 4th (extended coverage).
  • Adverse effects: Hypersensitivity (1-3%), GI complaints, hypoprothrombinemia.
• Carbapenems:
  • Inhibit cell wall synthesis (bactericidal).
  • Effective against Pseudomonas aeruginosa, gram-negative bacilli, anaerobes, MSSA, and Streptococcus.
  • Adverse effects: Low incidence; seizures in renal dysfunction.
• Monobactams (Aztreonam):
  • Inhibit cell wall synthesis (bactericidal).
  • Effective against gram-negative aerobic bacilli.
  • Adverse effects: Well-tolerated; rare rash or anaphylaxis.
• Aminoglycosides:
  • Inhibit RNA translation, destabilize cell wall (bactericidal).
  • Treat nosocomial gram-negative infections, P. aeruginosa in CF (inhaled).
  • Adverse effects: Nephrotoxicity, ototoxicity, neuromuscular blockade.
• Tetracyclines:
  • Inhibit RNA attachment (bacteriostatic).
  • Effective against gram-positive/negative microorganisms, Rickettsiae, Chlamydiae, Mycoplasmas, Spirochetes, Protozoa, Mycobacteria.
  • Adverse effects: GI issues; inhibit bone growth and absorption of Ca, Mg, Al, Fe; contraindicated in pregnancy.

Neuromuscular Blocking Agents (NMBAs)

• Cause skeletal muscle weakness or paralysis.
• Indications:
  • Endotracheal intubation, muscle relaxation during surgery, enhance patient-ventilator synchrony, reduce intracranial pressure, minimize oxygen consumption, facilitate procedures, maintain immobility.
• Physiology:
  • Acetylcholine (Ach) mediates nerve conduction and is broken down by acetylcholinesterase (AChE).
• Types:
  • Depolarizing Agents
  • Non-Depolarizing Agents

Non-Depolarizing Agents

• Compete with acetylcholine for receptor binding.
• Examples: Tubocurarine, Pancuronium, Rocuronium, Vecuronium.
• Action:
  • Competitive inhibition of acetylcholine; effects last 35-60 minutes and can be reversed by cholinesterase inhibitors (e.g., Neostigmine).
• Indications:
  • Longer-term paralysis, patient-ventilator synchrony, muscle relaxation during surgery, reduction of intracranial pressure, immobility in trauma, minimize oxygen consumption.
• Side Effects:
  • Vagolytic effects (tachycardia), increased blood pressure, histamine release (vasodilation, tachycardia, bronchospasm), hypoventilation, time to eliminate.

Depolarizing Agents

• Example: Succinylcholine.
• Action:
  • Prevents acetylcholine from binding, causing post-synaptic membrane depolarization. Shorter acting.
  • Causes total muscle paralysis in 60-90 seconds, lasts 10-15 minutes; no reversing agents.
• Indications:
  • Short-acting paralytic for intubation.
• Side Effects:
  • Sympathomimetic response (tachycardia, increased BP), vagal response (bradycardia, hypotension), histamine release, increased intracranial pressure, malignant hyperthermia, hypoventilation, muscle fasciculations.

NMBAs and Mechanical Ventilation

• Improve ventilation/oxygenation, reduce ventilator/intrathoracic pressures, improve synchrony.
• Beneficial in ARDS, status asthmaticus, inverse ratio ventilation.
• Sedation is always required!

Diuretic Agents

• Increase urine output to eliminate excess fluid.
• Primary goal: reduce extracellular fluid volume (ECFV) to lower blood pressure and rid excess interstitial fluid.
• Indications:
  • Excessive fluid conditions like congestive heart failure, hypertension, acute/chronic renal failure.
• Renal Structure and Function:
  • Nephron: functional unit (glomerulus, proximal tubule, Loop of Henle, distal tubule, collecting duct).
• Glomerular Filtration:
  • 99% of filtrate is reabsorbed, 1% excreted as urine. Increase urine output by interfering with reabsorption in the tubules.
  • Adult output = 0.5–1 mL/min or 30–60 mL/hr; < 30–60 mL/hr is oliguria, > 60 mL/hr is polyuria
• Electrolyte Reabsorption:
  • Na+: 70% proximal tubules, 20% loops of Henle, 10% distal tubules; Aldosterone increases Na and H2O reabsorption in distal tubule.
  • K+: Mostly in the proximal tubules
• Acid–Base Balance:
  • Low Cl– or K+ = metabolic alkalosis; Loss of HCO3 – buffer = metabolic acidosis.
• Diuretic Groups:
  • Osmotic, Carbonic anhydrase inhibitors, Thiazides, Loop, Potassium-sparing.

Classification of Diuretics

• Osmotic Diuretics:
  • Interfere with water reabsorption in the ascending loop of Henle and proximal tubule. Treat/prevent acute renal failure. (Mannitol).
• Carbonic Anhydrase Inhibitors:
  • Prevent reabsorption of sodium and bicarbonate in the proximal tubule to lower intraocular pressure (Glaucoma). (Acetazolamide, Methazolamide).
• Loop Diuretics:
  • Inhibit NaCl absorption in the ascending limb of Henle. Treat hypertension, CHF, renal failure, ascites. (Furosemide, Ethacrynic Acid).
• Thiazide Diuretics:
  • Block NaCl reabsorption in the distal tubule. Treat hypertension and CHF; first-line for mild hypertension. (Chlorothiazide, Chlorthalidone, Hydrochlorothiazide, Methyclothiazide).
• Potassium Sparing Diuretics:
  • Block sodium reabsorption in the distal tubule and collecting duct to counteract hypokalemic effects when treating chronic liver disease in CHF.
  • May cause hyperkalemia affecting potassium. (Spironolactone, Triamterene).
• Adverse Effects of Diuretics:
  • Hypovolemia which may cause dizziness, extreme thirst, excessive dryness, decreased urine output, dark-colored urine, constipation. Acid-base disorders : Low Cl– or K+ = metabolic alkalosis; Loss of HCO3 – buffer = metabolic acidosis..
    *Hypokalemia, Glucose changes ototoxicity.

Sedatives and Hypnotics

• Anti-Anxiety Agents:
  • Lorazepam , Midazolam, Haloperidol, Propofol
• Hypnotics:
  • Methaqualone, Flurazepam, Diazepam
• Action:
  • Depression of ascending reticular activating system results in loss of consciousness.
• Indications:
  • Sleep induction, relief of anxiety/depression, anticonvulsant, voluntary muscle relaxation.
• Side Effects:
  • Drowsiness, impaired performance/judgment, potential for abuse, hangover effect.
• Contraindications:
  • Hypothyroidism and Hypoadrenalism

Barbiturates

• Thiopental , Pentobarbital , Secobarbital , Amobarbital , Phenobarbital
• Used for:
  • Anesthesia induction, hypnotics, seizures control.
• Toxic Potential:
  • Depress neuron activity; high risk of addiction/abuse; reduced sleep quality; overdose leads to respiratory arrest or cardiovascular collapse.

Ethyl Alcohol

• Socially acceptable sedative-hypnotic. Disinhibiting and depressant effects.
• 400-600 mg/dl = respiratory arrest.
• Delirium tremens: CNS hyperactivity on withdrawal.

Opioid Analgesics

• Treat moderate to severe pain by binding to receptors for endogenous opioids.
• High doses: loss of consciousness, respiratory arrest.
• Side effects: respiratory depression, constipation, nausea/vomiting, antitussive effects.
• Routes: As needed or patient-controlled analgesia (PCA) pumps.
• Examples: Morphine, Opium, Fentanyl, Meperidine, Hydromorphone

Steroids

• Mimic natural hormones to regulate metabolic functions.
• Actions (ICU context):
  • Suppress inflammatory responses caused by hypersensitivity, decrease capillary permeability in edema.
• Indications:
  • Allergic/non-allergic inflammatory responses, asthma, COPD, suppression of immune response in organ transplant.
• Side Effects From Systemic Administration:
  • Cushing’s Disease, hypertension, atrophy of adrenal glands, obesity, suppression of growth, thinning of skin, osteoporosis, immunosuppression.
• Examples:
  • Hydrocortisone, Cortisone, Prednisone

Inotropes and Vasopressors

• Inotrope:
  • Increases myocardial contraction force.
• Vasopressor:
  • Stimulates contraction of smooth muscles in arteries and arterioles.
• Indications:
  • Shock, myocardial infarction, endotoxic septicemia, congestive heart failure.
• Side Effects:
  • Ectopic beats, tachycardia, anginal pain, vasoconstriction, dyspnea.

Catecholamines

• Norepinephrine (Levophed) and Epinephrine (Adrenalin):
  • Endogenous catecholamines secreted by adrenal medulla.
  • Net response is vasoconstriction and tachycardia.
• Dopamine (Intropin):
  • Releases norepinephrine dilating renal vessels, activates alpha receptors to increase SVR activating Beta1 Receptors Creating a Positive Inotropic Effect.
• Phenylephrine (Neo-Synephrine): Is a purely α-agonist.
  • Induces vasoconstriction, elevates blood pressure by elevating total peripheral resistance

Inotropic Agents

• Dobutamine (Dobutrex): Increases contractile force stimulating Beta1 Receptors.
  • Adverse effects: Arrhythmias, Increased in myocadial O2 consumption, Tachycardia hypotension

Cardiovascular Agents

• Anti-Arrhythmic Agents
  • Class IA:
    • Block Sodium Channels in The Atrium of The Myocardium (treating both: atrial and ventricular arrhythmias)
    • Block Repolarizing Potassium Currents, Leading to Prolonged Q-T Interval
    • Examples:
      • Quinidine: Efficacious in atrial fibrillation/flutter (AF/AFL).
      • Procainamide: Indicated for treatment of VT and torsades de pointes.
      • Disopyramide: Indicated for life-threatening VT and paroxysmal supraventricular tachycardia (PSVT).
  • Class IB: Limited to ventricular arrhythmias used for Acute MI or Arrhythmias during heart surgery (Lidocaine - Tocainide)
  • Class IC: Depression of Fast Sodium Channels; Slowing of Conduction in all Areas of Myocardium.(supraventricular or ventricular arrhythmias)
  • Class II: Blocks Beta Adrenergic Receptors in The Heart Decreasing The Effect of The Sympathetic Nervous System while decreasing cardiac workload, And Oxygen Consumption.(Propranolol - Atenolol)
  • Class III: Used to treat SVT and ventricular arrhythmias.(Amiodarone - Cordarone)
  • Class IV: Calcium channel Blockers Slows Conduction And Increases Refractoriness in The A-V Node by Blocking Calcium Channels .Increased Ventricular Rate with Atrial Fibrillation. (Verapamil - Diltiazem)

Miscellaneous

• Digoxin (Lanoxin): AV-blocking and vagotonic properties to reduce the heart rate.
  • Prolongs relative refractory period. Less effective than β-blockers
• Adenosine (Adenocard): Used to terminate SVT (12-second half-life)

Management and Pharmacotherapy of Advanced Cardiac Life Support

• Epinephrine: Directly Affects The Alpha And Beta1 Receptors Increasing Vasoconstriction also has β-adrenergic activity increases HR and impairs the delivery of O2 to the myocardium and CNS.
• Atropine: Indicated for asystole or PEA. Blocks action of acetylcholine with Short-lived chronotropic effect.
• Alternative Administration Routes:(NAVEL): Naloxone, Atropine, Vasopressin, Epinephrine, Lidocaine

Antithrombotic Agents

• Prevent or break up blood clots; formation initiated by injury to endothelium.
• Three Categories:
  • Anticoagulants (prevent fibrin clots), Antiplatelets (inhibit clot formation), Thrombolytics (break up thrombi).

Anti-Coagulant Agents

• Heparins: naturally present. Indicated for venous thromboembolism, pulmonary embolism, atrial fibrillation (AF), disseminated intravascular coagulation (DIC), and peripheral arterial embolism Antidote: Protamine sulfate
• Warfarin Coumadin): venous thrombosis, pulmonary embolism (PE), atrial fibrillation, valve replacement, coronary occlusion. Hemorrhage is a common side effect.

Anti-Platelet Agents Action

• Inhibits initial phase of Platelet Aggregation - Clopidogrel (Plavix) Acetylsalicylic Acid (Aspirin)

Thrombolytic Agents Action

• Converts Plasminogen to Plasmin, Which is Then Able to Degrade Fibrin in Clots restoring coronary blood flow indications include: Acute Myocardial Infarction Massive Pulmonary Embolism, Deep Vein Thrombosis. Acute Ischemic Stroke