Unit 10 – Drugs for Central Nervous System (CNS) Problems (Comprehensive Study Guide – Nursing Pharmacology) ⸻ 🧩 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. ⸻ 🧍‍♂️ 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 ⸻ 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 ⸻ 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. ⸻ 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. ⸻ 🧠 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. ⸻ 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). ⸻ 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). ⸻ ⚡ 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) ⸻ 💥 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 ⸻ 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. ⸻ 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. ⸻ 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. ⸻ 💪 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. ⸻ ⚙️ 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 ⸻ 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)

What is the Central Nervous System composed of?

The Central Nervous System (CNS) is composed of the brain and spinal cord.

What are the functions of the CNS?

It controls body movement, behavior, and cognitive function.

What are neurotransmitters?

Neurotransmitters are chemicals that transmit signals between neurons.

Name two types of neurotransmitters and provide examples.

Excitatory: Acetylcholine (ACh), epinephrine, norepinephrine; Inhibitory: Dopamine, serotonin, gamma-aminobutyric acid (GABA).

What is the critical balance needed for movement and which disorders arise from its imbalance?

The balance of dopamine and acetylcholine is critical for smooth movement; an imbalance can lead to disorders like Parkinson's Disease.

What is Parkinson's Disease (PD) primarily caused by?

Parkinson's Disease is caused by low dopamine production in the substantia nigra.

What are some key motor symptoms of Parkinson's Disease?

Tremors, bradykinesia, muscle rigidity, stooped posture, shuffling gait, difficulty rising, and a masklike facial expression.

What are some non-motor symptoms associated with Parkinson's Disease?

Constipation, urinary frequency, depression, anxiety, sleep issues, fatigue, and memory problems.

What is the goal of drug therapy for Parkinson's Disease?

The goal is to restore balance between dopamine and acetylcholine.

What is the action of Dopamine Agonists in PD treatment?

They mimic or increase dopamine to improve movement, coordination, and muscle control.

Name an example of a Dopamine Agonist medication.

Carbidopa/levodopa (Sinemet, Rytary), pramipexole (Mirapex ER), ropinirole (Requip), or rotigotine (Neupro patch).

What important nursing implication should be considered when administering Dopamine Agonists?

Give 30–60 minutes before meals on an empty stomach and monitor for orthostatic hypotension.

What are common side effects of Dopamine Agonists?

Hypotension, headache, nausea, insomnia, dyskinesia, and long-term use can lead to hallucinations and impulse control problems.

What is Multiple Sclerosis (MS) characterized by?

MS is characterized by the immune system attacking the myelin sheath around neurons, leading to muscle weakness and loss of coordination.

What drug class is used to slow the progression of MS?

Biological Response Modifiers (BRMs) are used to modify immune system activity and slow disease progression.

What is the main action of Acetylcholinesterase Inhibitors in Myasthenia Gravis treatment?

They prevent the breakdown of acetylcholine, improving nerve-muscle communication.

Name a medication used for treating Myasthenia Gravis.

Pyridostigmine (Mestinon) is commonly used.