Pharmacology Quiz on Neurology Medications

Antiemetic and Antinausea Drugs

• Antiemetics are drugs used to relieve nausea and vomiting.
• Seven categories, each with different mechanisms of action, primarily work by blocking pathways that induce vomiting.
• Chemoreceptors Trigger Zone (CTZ): brain area involved in nausea and vomiting sensation.

Metoclopramide (Reglan)

• Class: Prokinetic Drug
• Route: Oral, Parenteral (injection) prescription only
• Indications: Gastroesophageal reflux disease (GERD), delayed gastric emptying, and nausea/vomiting (N/V).
• Mechanism of Action: Blocks dopamine receptors in the CTZ, desensitizing it to GI tract impulses; stimulates GI tract peristalsis, enhancing stomach emptying.
• Contraindications: Seizure disorders, pheochromocytoma (adrenal gland tumor), breast cancer, and GI obstruction.
• Allergic to procaine or procainamide.
• Adverse Effects: Long-term use can cause irreversible tardive dyskinesia, extrapyramidal effects (e.g., tremors, muscle contractions, eye spasms, lip smacking, tongue protrusion).

Ondansetron (Zofran)

• Class: Serotonin Blocker
• Route: Oral, Injectible IV push over 2 minutes.
• Indications: Nausea/vomiting associated with chemotherapy and post-operative procedures, hyperemesis gravidarum (severe morning sickness).
• Mechanism of Action: Blocks serotonin receptors in the gastrointestinal tract, CTZ, and vomiting center.
• Contraindications: Known drug allergy. Cat B medication; concerns regarding developmental cleft palate during first trimester pregnancy.
• Adverse Effects: Known drug allergy

Meclizine (Antivert)

• Class: Antihistamine (H1 Receptor Blocker)
• Route: Oral (PO)
• Indications: Motion sickness, non-productive cough, allergy symptoms, sedation, vertigo.
• Mechanism of Action: Inhibits Acetylcholine (ACH) by binding to H1 Receptors; prevents cholinergic stimulation in vestibular and reticular areas to prevent nausea and vomiting.
• Contraindications: Shock, lactation.
• Adverse Effects: Drowsiness, fast heartbeat, hives, itching, rash, headaches.

Promethazine (Phenergan)

• Class: Antidopaminergic
• Route: Oral (PO), Intramuscular (IM) (preferred), Intravenous (IV) (common).
• Indications: Psychotic disorders, intractable hiccups, hay fever relief/prevention, allergic conjunctivitis.
• Mechanism of Action: Blocks dopamine receptors in the chemoreceptor trigger zone.
• Contraindications: Children under two years old (risk of fatal respiratory depression)
• Adverse Effects: Sedation (most common, may be beneficial), drowsiness, dry mouth, lightheadedness.

Scopolamine (Transderm-Scop, Scopace)

• Class: Anticholinergic blocker
• Route: 72-hour transdermal patch.
• Indications: Nausea/vomiting associated with motion sickness (most common use), postoperative N/V, reducing secretions before surgery.
• Mechanism of Action: Binds to and blocks Acetylcholine (ACh) receptors in the inner ear labyrinth, blocking nauseating stimuli to the vomiting center (CTZ), and reticular formation.
• Contraindications: Glaucoma, pyloric obstruction, urinary bladder neck obstruction.
• Adverse Effects: Blurred vision, confusion, hallucinations, urinary retention.

Adrenergic Agonists/Sympathomimetics

• The autonomic nervous system (ANS) and sympathetic nervous system (SNS) play a crucial role in these drugs.
• Catecholamines (Epinephrine, Norepinephrine, Dopamine): endogenous receptors (Alpha 1 & 2; Beta 1 & 2; and Dopamine).
• Alpha 1: postsynaptic cells
• Alpha 2: presynaptic cells
• Beta 1: primarily in the heart
• Beta 2: primarily in the lungs and arterioles
• Dopamine: dilates blood vessels, increasing blood flow to organs like kidneys.
• Adrenergic medications mimic the actions of neurotransmitters in the SNS.
• Indications: Cardiovascular conditions (heart failure, shock), respiratory issues (bronchodilation, nasal congestion), and genitourinary conditions (overactive bladder, BPH).

Epinephrine (Epi-Pen)

• Class: Alpha and Beta adrenergic agonist
• Indications: Severe allergic reactions (anaphylaxis), bronchospasm, cardiac arrest, asthma.
• Mechanism of Action: Binds to alpha receptors, causing vasoconstriction.
• Contraindications: Hypertension, hypersensitivity.

Dopamine (Inotropen)

• Class: Beta-1 adrenergic agonist.
• Indications: Low dose: vasodilation blood flow to brain, heart, kidneys, mesentery, Increased cardiac contractility and output.
• Mechanism of Action: increasing blood flow to various organs

Mirabegron (Myrbetriq)

• Classification: GU Adrenergic Agonist
• Route: Oral (PO).
• Indication: overactive bladder.
• Mechanism of Action: Relaxes detrusor muscles, increasing bladder capacity.

Tamsulosin (Flomax)

• Class: Alpha adrenergic blocker
• Route: Oral (PO)
• Indications: Benign prostatic hyperplasia (BPH), kidney stones, and urinary retention (in both males and females),
• Mechanism of Action: Block alpha-adrenergic receptors on smooth muscle fibers within the prostate and bladder. Decreases constriction to improve urinary flow.

Sotalol (Betapace)

• Class: Nonselective Beta Blocker.
• Route: Oral (PO).
• Indication Treatment of difficult-to-treat cardiac dysrhythmias.

Metoprolol (Lopressor)

• Class: Beta-1 blocker
• Route: IV, Oral (PO)
• Indication: High blood pressure, Angina, and heart failure.
• Mechanism of Action: Acts on beta-1 receptors in the heart, reducing the effects of catecholamines on cardiac function.

Memantine (Namenda)

• Class: NMDA receptor antagonist
• Route: Oral (PO)
• Indication: Treatment of Alzheimer's disease.
• Mechanism of Action: Blocks stimulation of NMDA receptors, reducing the stimulation, and potentially stopping the breakdown, associated with Alzheimer's disease.

Pyridostigmine (Mestinon)

• Class: Indirect-acting cholinergic drug
• Indications: Myasthenia gravis, reversing nondepolarizing neuromuscular blocking agents.
• Mechanism of Action: Increases acetylcholine by inhibiting acetylcholinesterase.

Oxybutynin (Ditropan)

• Class: Synthetic antimuscarinic medication
• Indications: Overactive bladder and neurogenic bladder associated with spinal cord injuries.
• Mechanism of Action: Blocks muscarinic Acetylcholine (ACh) receptors in the bladder, reducing bladder spasms and increasing bladder capacity.

Dicyclomine (Bentyl)

• Class: Synthetic Antispasmodic Cholinergic Blocker
• Indications: Irritable bowel syndrome, functional gastrointestinal tract disturbances.
• Mechanism of Action: Blocks muscarinic action of acetylcholine on gastrointestinal smooth muscle, inhibiting spasms and contractions.