Unit 10 – Drugs for Central Nervous System (CNS) Problems
(Comprehensive Study Guide – Nursing Pharmacology)
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🧩 Central Nervous System (CNS) Overview
• CNS = Brain + Spinal Cord
• Controls body movement, behavior, and cognitive function.
• Neurotransmitters are chemicals that transmit signals between neurons.
• Excitatory: Acetylcholine (ACh), epinephrine, norepinephrine
• Inhibitory: Dopamine, serotonin, gamma-aminobutyric acid (GABA)
⚖️ Balance of dopamine and acetylcholine is critical for smooth movement.
An imbalance leads to disorders like Parkinson’s Disease.
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🧍♂️ Parkinson’s Disease (PD)
Cause
• Progressive CNS disorder due to low dopamine production in the substantia nigra.
• Too little dopamine → too much acetylcholine, causing impaired motor control.
Key Symptoms
Motor:
• Tremors (“pill-rolling”)
• Bradykinesia (slow movements)
• Muscle rigidity, stiffness
• Stooped posture, shuffling gait
• Difficulty rising, “freezing in place”
• Masklike facial expression
Nonmotor:
• Constipation, urinary frequency
• Depression, anxiety, hallucinations
• Sleep issues, fatigue
• Memory problems
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Drug Classes for PD
Goal: Restore balance between dopamine and acetylcholine.
1️⃣ Dopamine Agonists
Action: Mimic or increase dopamine. Improve movement, coordination, and muscle control.
Examples:
• carbidopa/levodopa (Sinemet, Rytary)
• pramipexole (Mirapex ER)
• ropinirole (Requip)
• rotigotine (Neupro patch)
Nursing Implications & Teaching:
• Give 30–60 min before meals (empty stomach).
• Avoid protein-rich foods (reduces absorption).
• Monitor for orthostatic hypotension — rise slowly.
• Don’t crush extended-release tablets.
• Neupro patch: rotate sites, don’t reuse within 14 days.
• Avoid vitamin B6 unless taken with carbidopa.
• Takes 2–3 weeks for full effect.
Side Effects:
• Hypotension, headache, nausea, insomnia
• Dyskinesia (abnormal movements)
• “On/off effect” – medication wears off quickly
• Long-term use → hallucinations, impulse control problems
Adverse Effects:
• Neuroleptic malignant syndrome: fever, rigidity, confusion
• Psychosis, severe hypotension
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2️⃣ COMT Inhibitors
Action: Block COMT enzyme → prolong dopamine activity.
Examples:
• entacapone (Comtan)
• tolcapone (Tasmar)
Nursing Implications:
• Always give with carbidopa/levodopa.
• Monitor liver function (q6 months) – risk of liver failure (especially tolcapone).
• Harmless side effect: brown-orange urine.
• Rise slowly to prevent hypotension.
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3️⃣ MAO-B Inhibitors
Action: Inhibit MAO-B enzyme → prevents dopamine breakdown.
Examples:
• selegiline (Eldepryl)
• rasagiline (Azilect)
• safinamide (Xadago)
Teaching:
• Avoid foods high in tyramine → hypertensive crisis risk.
(Aged cheese, wine, beer, cured meats, soy sauce, yogurt, avocados, bananas)
• Monitor BP closely.
• Avoid OTC decongestants or stimulants.
• Can cause insomnia, dizziness, dry mouth, or constipation.
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🧠 Alzheimer’s Disease (AD)
Cause
• Progressive neurodegenerative disorder leading to memory loss, confusion, and poor judgment.
• Loss of acetylcholine (ACh) and buildup of amyloid plaques and neurofibrillary tangles in the brain.
Symptoms
• Early: forgetfulness, confusion, mood changes.
• Late: loss of reasoning, personality changes, inability to perform ADLs.
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Drug Classes for AD
1️⃣ Cholinesterase Inhibitors
Action: Block enzyme acetylcholinesterase (AChE) → increases ACh → improves memory and function.
Examples:
• donepezil (Aricept)
• rivastigmine (Exelon)
• galantamine (Razadyne)
Side Effects:
• Nausea, vomiting, diarrhea
• Loss of appetite, GI discomfort
• Drowsiness, headache, insomnia
• Muscle cramps, bradycardia
Adverse Effects:
• Dysrhythmias, GI bleeding, hallucinations
• Overstimulation of parasympathetic system (too much ACh)
Nursing Implications:
• Give at bedtime to reduce nausea.
• Monitor weight, HR, and mental changes.
• Report black/tarry stools or vomiting blood.
• Avoid OTC anticholinergics (they reduce effectiveness).
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2️⃣ NMDA Blockers
Action: Block NMDA receptor → decreases glutamate activity → prevents neuron death.
Example:
• memantine (Namenda)
Used in: Moderate to severe AD (often combined with donepezil).
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⚡ Epilepsy / Seizure Drugs (AEDs)
Purpose
Reduce excessive electrical activity in the brain and prevent seizures.
Common AEDs:
• phenytoin (Dilantin) – prevents neuron excitation
• topiramate (Topamax) – broad-spectrum seizure control
Topiramate Key Points:
• Side effects: dizziness, drowsiness, taste changes, paresthesias (“pins and needles”)
• Adverse: metabolic acidosis, ↑ ammonia → confusion, lethargy, vomiting
• Monitor: serum bicarbonate & ammonia levels
• Teaching: stay hydrated, report mental status changes, don’t crush tablets
• Contraindicated in pregnancy (teratogenic)
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💥 Multiple Sclerosis (MS)
Pathophysiology
• Autoimmune disease where the immune system attacks myelin (fatty sheath around neurons).
• Leads to nerve signal disruption → muscle weakness and loss of coordination.
• Common type: Relapsing-Remitting MS (RRMS) – periods of flare-ups and remission.
Common Symptoms
• Fatigue, weakness, difficulty walking
• Double vision or blurred vision
• Tingling or numbness
• Bladder/bowel dysfunction
• Depression, poor concentration
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Drug Therapy for MS
1️⃣ Biological Response Modifiers (BRMs)
Action: Modify immune system activity and slow disease progression.
Examples:
• beta-interferons (Avonex, Betaseron, Rebif, Extavia, Plegridy)
• glatiramer (Copaxone)
• fingolimod (Gilenya)
• teriflunomide (Aubagio)
Side Effects:
• Flu-like symptoms, headache, fatigue
• Elevated liver enzymes, slow HR
• Thinning scalp hair
Nursing Teaching:
• Rotate injection sites.
• Monitor liver enzymes, CBC, and heart rate.
• Avoid live vaccines.
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2️⃣ Monoclonal Antibodies
Action: Destroy lymphocytes that attack myelin.
Examples:
• alemtuzumab (Lemtrada)
• natalizumab (Tysabri)
• ocrelizumab (Ocrevus)
Side Effects:
• Increased risk of infection
• Headache, rash, fatigue
• GI upset
Nursing Teaching:
• Given IV every few months to yearly.
• Monitor for infusion reactions and infection signs.
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3️⃣ Neurologic Drugs
Examples:
• dimethyl fumarate (Tecfidera) – reduces CNS inflammation
• dalfampridine (Ampyra) – improves walking by increasing nerve conduction
Teaching:
• Take daily; don’t crush tablets.
• Watch for GI symptoms and dizziness.
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💪 Amyotrophic Lateral Sclerosis (ALS)
Description
• Progressive, fatal disorder destroying motor neurons → paralysis.
• Death usually occurs within 3–5 years of diagnosis.
Drug Therapy
Glutamate Antagonists
Example:
• riluzole (Rilutek, Tiglutik)
Action: Inhibits glutamate release → slows neuron damage → prolongs life by months.
Side Effects:
• Weakness, nausea, dizziness
• Liver toxicity (↑ liver enzymes)
• Neutropenia, anemia
Nursing Implications:
• Monitor liver enzymes before and during therapy.
• Report jaundice or dark urine.
• Take on an empty stomach (1 hr before or 2 hrs after meals).
• Avoid alcohol.
• Don’t breastfeed while on this med.
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⚙️ Myasthenia Gravis (MG)
Description
• Autoimmune disease destroying acetylcholine receptors at neuromuscular junction.
• Causes muscle weakness and fatigue, especially in eyes, mouth, throat.
Symptoms
• Ptosis (drooping eyelids)
• Difficulty chewing/swallowing
• Weakness in arms, legs, or respiratory muscles
• Worsens with activity, improves with rest
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Drug Therapy
Acetylcholinesterase Inhibitors
Action: Prevent breakdown of acetylcholine → improves nerve–muscle communication.
Example:
• pyridostigmine (Mestinon)
Dosage: Usually every 4–6 hours, depending on patient response.
Side Effects:
• Nausea, vomiting, abdominal cramps, diarrhea
• Increased salivation, sweating
• Bradycardia, hypotension
Adverse:
• Cholinergic crisis (too much medication):
→ extreme weakness, bradycardia, bronchospasm, respiratory arrest.
Nursing Implications:
• Use with caution in asthma, COPD, bradycardia.
• Give doses at same time each day to maintain muscle strength.
• Monitor for myasthenic vs. cholinergic crisis.
• Give meds 30–45 min before meals to prevent aspiration.
Patient Teaching:
• Take missed dose ASAP (but skip if close to next dose).
• Don’t double dose.
• Avoid alcohol and sedatives.
• Report muscle weakness or breathing difficulty.
• Keep atropine available (antidote for cholinergic crisis)
Updated 114d ago
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