Term Two CNS Stimulants Notes

Narcolepsy and CNS stimulants (Term Two) notes

Overview

  • Topic: CNS stimulants (Term Two, blocks 2BSN 13, 14, 15, 16). Focus on narcolepsy, ADHD, and related medications, including mechanisms, indications, adverse effects, and nursing considerations. Also covers related depressants, anesthetics, opioids, and migraine therapies as discussed in the transcript.

Narcolepsy

  • Narcolepsy: a chronic sleep disorder characterized by overwhelming daytime sleepiness and sudden attacks of sleep. It is caused by a deficiency in hypocretin (also called orexin), a neurotransmitter that promotes wakefulness.
  • Pharmacologic goal: CNS stimulants help compensate for hypocretin deficiency by revving up the CNS to maintain alertness.

ADHD (Attention Deficit Hyperactivity Disorder)

  • ADHD involves dysregulation of dopamine and norepinephrine in the brain, especially the prefrontal cortex, affecting impulse control, decision making, and attention.
  • Misconception: ADHD is not simply a problem of having too much energy; it is a dysregulation of neurotransmitters that affects attention, focus, and impulse control.
  • Neurotransmitters involved: dopamine (DA) and norepinephrine (NE). Treatment aims to strengthen signaling of these transmitters in the prefrontal cortex to improve attention and impulse control.

CNS stimulants: general mechanism and purpose

  • Primary effect: increase wakefulness, attention, and impulse control by increasing dopaminergic and noradrenergic activity in the CNS.
  • Three key mechanisms (Amphetamines and methylphenidate):
    1) Promote the release of dopamine and norepinephrine from storage sites in the brain.
    2) Bind to transporters that normally reabsorb these neurotransmitters, decreasing reuptake and increasing synaptic DA and NE.
    3) Result: higher concentrations of dopamine and norepinephrine in the synaptic cleft lead to improved wakefulness, focus, motivation, and impulse control.
  • Net effect: higher availability of DA and NE in the prefrontal cortex improves attention, focus, and reduces impulsivity.

Major CNS stimulants (generic names and indications)

  • Amphetamines and methylphenidate are the core CNS stimulants discussed.
  • Brand/generic names:
    • Methamphetamine and dextroamphetamine (amphetamines)
    • Methylphenidate (brand names: Ritalin, Concerta)
    • Lisdexamfetamine (brand name Vyvanse)
  • Indications: ADHD and narcolepsy.
  • Visual mnemonic for CNS stimulants (memory aid):
    • Start: amphetamines (start/amphetamines)
    • Metal fence: methylphenidate (methyl-phenidate)
    • Indicated: methamphetamines (ADHD)
    • Indicated (continued): CNS stimulants for narcolepsy
    • Side effects (SPEED mnemonic): S = skin rashes or sleeplessness; P = palpitations/increased BP; E = excessive excitement or euphoria; E = eating less (anorexia); D = dizziness (and potential dependence with long-term use)

Pharmacodynamics: how amphetamines and methylphenidate work

  • 1) Amphetamines promote release of dopamine (DA) and norepinephrine (NE) from storage sites, increasing their availability in the brain.
  • 2) They bind to transporters that normally reabsorb DA and NE, thereby inhibiting reuptake and increasing synaptic DA/NE.
  • 3) This yields higher synaptic concentrations of DA/NE, increasing wakefulness, focus, motivation, impulse control, and alertness.
  • 4) Resulting pharmacologic effect: higher DA/NE in the synaptic cleft leads to improved attention span, focus, and impulse control in ADHD; increased wakefulness in narcolepsy.
  • For narcolepsy and ADHD, these drugs aim to normalize prefrontal cortex signaling by boosting DA/NE.

Generic names and brand examples

  • Amphetamines: methamphetamine, dextroamphetamine
  • Methylphenidate: Ritalin, Concerta
  • Lisdexamfetamine: Vyvanse
  • Indications: ADHD and narcolepsy

Nursing visual mnemonic and practical notes

  • Visual mnemonic (for quick recall):
    • Amphetamines → indicated for ADHD; Methylphenidate → indicated for ADHD; Methamphetamines → indicated for ADHD; Modafinil → for narcolepsy/shift work sleep disorder (non-amphetamine stimulant)
  • Side effects (SPEED): Skin rashes / sleeplessness; Palpitations / hypertension; Excessive excitement / euphoria; Eating less (anorexia); Dizziness; (Note: longer-term use may lead to tolerance and dependence)
  • Important caveat: stimulants have abuse potential and require careful monitoring.

Side effects and adverse effects (stimulants)

  • Common and high-yield adverse effects (tachycardia, hypertension, dizziness, anorexia, insomnia, etc.)
  • Specific adverse effects mnemonic for migraine relates to other medications, but stimulant-related adverse effects include:
    • Tachycardia and hypertension
    • Cardiac dysrhythmias; sudden cardiac death (rare but critical in high-risk individuals)
    • Psychosis or stimulant-induced mania in susceptible individuals
    • Seizures (rare but reported with stimulant use)
    • Growth suppression in children due to appetite suppression
    • Tolerance and dependence with long-term use
  • Note on dependence: long-term use can lead to tolerance, requiring higher doses to achieve the same effect, and potential dependence.

Nursing responsibilities for stimulant therapy (ADHD/narcolepsy)

  • Baseline assessments:
    • Obtain baseline ECG to assess cardiac risk (cardiac dysrhythmias, sudden death risk)
    • Baseline BP and heart rate
    • Baseline weight (to monitor growth suppression)
    • History of substance abuse, cardiovascular diseases, and psychiatric disorders (contraindications include known structural heart disease, uncontrolled hypertension, ischemic heart disease, bipolar disorder, schizophrenia, etc.)
  • Monitoring during therapy:
    • Monitor for signs of abuse/diversion (e.g., early refills, pattern of requests)
    • Monitor weight and growth; assess for growth suppression; consider drug holidays to allow catch-up growth
    • Monitor BP and HR; assess for tachycardia, hypertension, cardiac symptoms
    • Assess appetite and sleep; ensure dosing does not cause severe insomnia
  • Administration guidelines:
    • Administer the first dose early in the day; avoid evening dosing to prevent insomnia
    • Administer the last dose at least 4-6 hours before bedtime to minimize insomnia; this can be expressed as 4 ext{ to } 6 ext{ hours} before sleep
    • Administer with meals or after meals to counteract appetite suppression; awareness of anorexia risk
    • Consider drug holidays (weekends or summer) to reduce growth suppression and allow catch-up growth
  • Education and safety:
    • Counsel families to monitor child’s weight/height regularly
    • Advise avoiding caffeine and other stimulants to prevent excessive stimulation
    • Advise storing medications securely due to abuse risk
    • Warn against abrupt stopping; withdrawal symptoms may occur (mood changes, fatigue, depression, etc.)

Non-amphetamine CNS stimulants

  • Modafinil (brand name Provigil)
    • Indications: narcolepsy and shift-work sleep disorder (circadian rhythm-related sleepiness)
    • Mechanism: promotes wakefulness; literature notes include increasing extracellular DA and NE, and histaminergic/orexinergic system activation; also inhibits reuptake of dopamine and norepinephrine; promotes wakefulness via orexin/hypocretin pathways and histaminergic systems
    • Advantages vs amphetamines: lower abuse potential and lower risk of dependence and withdrawal compared with classic stimulants
    • Important caveat: not a substitute for good sleep hygiene; not a substitute for proper sleep practices
  • Anorexigens (short-term pharmacologic aid for obesity): Phentermine
    • Mechanism: stimulates the release of norepinephrine (and some dopamine) in the hypothalamus (appetite center)
    • No significant effect on serotonin in terms of mood/psychosis in the same way as other serotonergic agents
    • Indications: short-term treatment of obesity
    • Considerations: high risk for tolerance and abuse; use alongside diet and exercise; not a magic pill; monitor cardiovascular status
  • Respiratory stimulants (neonatal and post-anesthesia support)
    • Agents: Doxapram, caffeine, theophylline, aminophylline
    • Indications: neonatal apnea; respiratory depression following anesthesia
    • Mechanism: primarily central stimulation of the brainstem/medulla to stimulate the respiratory center; some agents may cause bronchodilation
    • Nursing considerations: ICU-level monitoring; monitor respiratory rate and pattern; monitor oxygenation; assess for adverse effects

Non-amphetamine stimulants for migraines (abortive therapy)

  • Sumatriptan (brand: Imitrex) and ergotamine (ergot alkaloids)
    • Indications: abortive therapy for acute migraine and cluster headaches (not preventive)
    • Mechanism: activation of alpha-adrenergic receptors and serotonin 5-HT1B/1D receptors leading to vasoconstriction and reduced inflammation, thereby relieving throbbing migraine pain
    • Adverse effects — migraine meds mnemonic TRIPTAN:
    • T: Tingling, flushing, warmth
    • R: Risk of angina (cardiac ischemia due to vasoconstriction)
    • I: Increased blood pressure (often in the setting of vasoconstriction)
    • P: Pain in chest/neck/pressure; signs of coronary vasospasm
    • T: Tiredness or dizziness
    • A: Abdominal pain
    • N: Nausea and vomiting
    • Contraindications and cautions:
    • History of coronary artery disease (CAD), uncontrolled hypertension, ischemic stroke are contraindications for sumatriptan/ergotamine due to vasoconstrictive risk
    • Administration guidelines:
    • Use at the first sign of migraine for best effect
    • Do not exceed prescribed doses; risk of medication-overuse headache with overuse
    • Not used as preventive therapy
    • Patient education:
    • Report adverse effects such as chest pain, tightness, shortness of breath, severe vasospasm symptoms
    • Seek urgent care if signs of heart attack occur

Migraine therapy consolidation and cautions

  • CNS stimulants do not replace preventive migraine therapies; triptans/ergotamines are used for acute management when migraine occurs
  • Monitor CAD, uncontrolled HTN, and ischemic stroke history before prescribing triptans or ergots
  • Ensure early use at onset of migraine; avoid overuse to prevent medication-overuse headaches

Local anesthetics and general anesthetics (brief review from transcript)

  • Local anesthetics
    • Indication: block pain in a localized region (e.g., suturing, dental work, epidurals)
    • Mechanism: block voltage-gated Na+ channels in nerve cells, preventing influx of Na+ needed for nerve impulses (nociception)
    • Adverse effects: tingling, itching, headaches, blurred vision, nausea/vomiting; LAST (local anesthetic systemic toxicity) with risk of CNS excitation, seizures, and cardiac arrest
    • Nursing considerations: monitor return of sensation and motor/sensory/autonomic function; monitor for LAST and treat promptly if symptoms arise
  • General anesthetics
    • Examples: propofol, halothane
    • Indications: induction of anesthesia; analgesia and muscle relaxation for surgery
    • Mechanism: potentiate GABA, the primary CNS inhibitory neurotransmitter; suppress excitatory pathways (glutamate)
    • Risks: malignant hyperthermia in susceptible individuals, a genetic predisposition; signs include tachycardia, rapid shallow breathing, hyperthermia, muscle rigidity, rhabdomyolysis, brown/red urine (myoglobinuria), sweating
    • Management of malignant hyperthermia: stop triggering agents immediately, administer dantrolene (muscle relaxant), provide supportive care (oxygen, cooling, fluids); monitor temperature, cardiac rhythm, and renal function
    • Postoperative considerations: monitor airway patency, spontaneous breathing, consciousness, and cardiovascular stability; ensure fasted state to prevent aspiration pneumonia; local vs general anesthesia differences; local anesthetics can be used for suturing, dental work, epidurals

Opioid analgesics (narcotics) – last section of the transcript’s discussion

  • Drug class: opioid agonists; schedule II controlled substances (S2)
  • Common agents: morphine, hydromorphone (Dilaudid), fentanyl, oxycodone
  • Indications: moderate to severe pain; first-line in cancer pain and palliative care
  • Mechanism: act on mu, kappa, and delta opioid receptors to alter perception of pain and provide analgesia; produce euphoria
  • Adverse effects (Morphin mnemonic): M-O-R-P-H-I-N-S
    • Miosis (pinpoint pupils)
    • Respiratory depression (most dangerous adverse effect)
    • Odder effects including pruritus/itching
    • Hypotension (orthostatic) and sedation
    • Nausea and vomiting
    • Sedation
    • (Additional notes: constipation commonly occurs; urinary retention can occur; euphoria and mood changes)
  • Respiratory depression: critical red flag if respiratory rate <12 breaths per minute; hold dose and notify prescriber
  • Pain assessment: use standardized pain scales before and 30-60 minutes after administration to evaluate effectiveness
  • Constipation and urinary retention: prophylaxis with fiber, fluids, stool softeners or laxatives as needed
  • Naloxone (Narcan): antidote for opioid overdose or toxicity, kept at bedside for rapid reversal if needed
  • Administration tips: IV push slowly over several minutes to reduce nausea and pruritus; monitor for adverse effects; educate on constipation prevention
  • Drug interactions: caution with other CNS depressants (benzodiazepines, anticonvulsants) due to additive CNS depression

Practical takeaways and exam-ready points

  • Narcolepsy is linked to hypocretin deficiency; stimulants help compensate by increasing wakefulness and alertness
  • ADHD treatment hinges on boosting DA/NE signaling in the prefrontal cortex to improve attention and impulse control
  • Amphetamines and methylphenidate act by promoting neurotransmitter release and blocking reuptake; expect appetite suppression and potential growth effects in children
  • Non-amphetamine stimulants (modafinil) offer wakefulness with lower abuse risk; used for narcolepsy and shift-work sleep disorder; not a substitute for sleep hygiene
  • Obesity pharmacotherapy (phentermine) increases NE in the hypothalamus to suppress appetite; risks include abuse and cardiovascular effects; use as adjunct to diet/exercise
  • Respiratory stimulants support neonatal apnea and post-anesthesia respiratory depression; monitor respiratory status closely
  • Triptans and ergots are abortive therapies for migraines; act via vasoconstriction; contraindicated in CAD, uncontrolled HTN, and ischemic stroke; risk of medication-overuse headache if overused
  • Local and general anesthetics have distinct mechanisms and major safety considerations (LAST, malignant hyperthermia); ensure monitoring and readiness to manage complications
  • Opioid analgesics provide potent analgesia but carry significant risks: respiratory depression, constipation, urinary retention, addiction potential, and overdose; use naloxone for reversal if needed; monitor respiratory rate and pain relief; avoid concurrent CNS depressant use where possible
  • Across all CNS agents, thorough baseline assessment (cardiovascular status, psychiatric history, substance use) and ongoing monitoring are essential; patient education on risks, safe use, and adherence is critical

Key formulas and notations (LaTeX)

  • Dosing timing concept: last stimulant dose before bedtime should be at least 4-6 ext{ hours} prior to sleep to minimize insomnia.
  • Schedule designation: CNS stimulants are often controlled substances; many are classified as \text{Schedule II} (S2).
  • Neurotransmitter action summary:
    \text{Increased DA/NE in synaptic cleft} \Rightarrow \text{improved wakefulness and attention}.
  • Modafinil mechanism note (conceptual): modafinil promotes wakefulness by influencing multiple wake-promoting systems, including orexin (hypocretin) pathways, histaminergic systems, and possibly extracellular DA/NE dynamics, with less abuse potential than classic stimulants.

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