13.5 CNS Stimulants and Nonstimulants

CNS stimulants and nonstimulants are the primary drug classes used to treat ADHD and narcolepsy. They work by increasing dopamine and/or norepinephrine activity in the brain, which improves focus, reduces impulsivity, and promotes wakefulness.

Stimulants like methylphenidate and amphetamines are first-line treatments, but nonstimulants offer important alternatives for patients who can't tolerate stimulants or have a history of substance abuse. Understanding the pharmacology, side effects, drug interactions, and nursing considerations for these medications is essential for safe patient care.

CNS Stimulants and Nonstimulants

CNS Stimulants and Nonstimulants for Disorders

ADHD is the primary indication for both drug classes. CNS stimulants improve attention, reduce impulsivity, and decrease hyperactivity by boosting dopamine and norepinephrine in the prefrontal cortex, the brain region responsible for executive function.

The two main stimulant categories work through slightly different mechanisms:

• Methylphenidate (Ritalin, Concerta) blocks the reuptake of dopamine and norepinephrine, keeping more of these neurotransmitters available in the synapse. This increases alertness, attention, and energy.
• Amphetamines (Adderall, Dexedrine) actively increase the release of dopamine and norepinephrine from nerve terminals, in addition to blocking reuptake. This enhances focus, concentration, and wakefulness.

The distinction matters: methylphenidate prevents removal of neurotransmitters, while amphetamines push more neurotransmitter out into the synapse. Both raise dopamine and norepinephrine levels, but through different pathways.

Narcolepsy is the other major indication. CNS stimulants promote wakefulness and reduce excessive daytime sleepiness in these patients.

Nonstimulants provide alternatives for both conditions:

• Atomoxetine (Strattera) is a selective norepinephrine reuptake inhibitor (SNRI, but not the antidepressant class). It increases norepinephrine levels to improve attention and reduce impulsivity in ADHD. It has no significant dopamine activity, which is why it has lower abuse potential.
• Modafinil (Provigil) and Armodafinil (Nuvigil) are wakefulness-promoting agents believed to increase dopamine levels. They're primarily used for narcolepsy and excessive daytime sleepiness rather than ADHD.

Pharmacology of ADHD and Narcolepsy Medications

All of these medications must cross the blood-brain barrier to reach the CNS and exert their therapeutic effects.

Mechanism summary:

• CNS stimulants enhance dopamine and norepinephrine neurotransmission in the prefrontal cortex
• Atomoxetine selectively increases norepinephrine
• Modafinil/Armodafinil primarily increase dopamine to promote wakefulness

Side effects of CNS stimulants:

• Insomnia (especially if dosed too late in the day)
• Decreased appetite and weight loss
• Headache
• Irritability and anxiety
• Increased heart rate and blood pressure (cardiovascular stimulation)

Side effects of nonstimulants:

• Atomoxetine: nausea, dry mouth, fatigue, decreased appetite
• Modafinil/Armodafinil: headache, nausea, anxiety, insomnia

Drug interactions to watch for:

The modafinil/contraceptive interaction is one that's easy to overlook. Patients using hormonal birth control should be counseled to use a backup method.

Nursing Considerations for CNS Medications

Administration:

• Give medications at the prescribed dose and on schedule. Stimulants are typically dosed in the morning to avoid insomnia.
• Follow directions regarding food; some formulations can be taken with or without food, while others have specific instructions.
• Do not crush extended-release formulations (e.g., Concerta).

Monitoring for therapeutic response:

1. Look for improvement in attention, concentration, and wakefulness
2. Observe for reduction in impulsivity and hyperactivity
3. In narcolepsy patients, assess whether excessive daytime sleepiness has decreased

Monitoring for adverse effects:

• Check vital signs at each visit, with particular attention to heart rate and blood pressure
• Assess sleep patterns, appetite, and weight changes regularly
• Observe for mood changes, irritability, anxiety, or signs of depression
• In children and adolescents on atomoxetine, monitor for suicidal ideation (FDA black box warning)

Additional nursing actions:

• Perform regular medication reconciliation to catch dangerous interactions
• Collaborate with providers for dose adjustments when therapeutic response is inadequate or side effects are problematic
• Be aware that some of these medications may be used off-label for conditions not FDA-approved (e.g., modafinil for shift-work sleep disorder)

Patient Education for Attention and Sleep Medications

• Explain what the medication does and what realistic outcomes to expect. Stimulants typically work within 30-60 minutes; atomoxetine may take 4-6 weeks for full effect.
• Review proper dosage timing. Stimulants should generally be taken early in the day. Missed doses should not be doubled.
• Discuss common side effects and practical management strategies: eating a good breakfast before the stimulant kicks in can help with appetite loss; maintaining a consistent bedtime routine helps with insomnia.
• Instruct patients to report severe or persistent side effects to their healthcare team, including chest pain, palpitations, or mood changes.
• Advise patients to avoid alcohol and use caution when operating machinery, especially when starting a new medication or adjusting doses.
• Encourage a balanced diet, regular exercise, and good sleep hygiene to complement pharmacologic treatment.
• Stress the importance of regular follow-up appointments for monitoring vital signs, growth (in pediatric patients), and treatment effectiveness.
• For patients on modafinil/armodafinil, specifically counsel about the interaction with hormonal contraceptives.
• Provide resources for additional support such as counseling, behavioral therapy, or support groups, which are especially valuable alongside medication for ADHD.

Regulatory and Safety Considerations

Most CNS stimulants (methylphenidate, amphetamines) are Schedule II controlled substances under the DEA, meaning they have a high potential for abuse and dependence. This classification affects prescribing and dispensing:

• Prescriptions typically cannot be called in and may require a new written prescription each time (no refills on Schedule II)
• Nurses should be aware of diversion risks, especially in settings where these medications are stored

Tolerance and dependence: Long-term stimulant use can lead to tolerance, where higher doses are needed for the same therapeutic effect. Some patients may develop physical or psychological dependence. This is one reason nonstimulants like atomoxetine are preferred for patients with a history of substance use disorder.

There is ongoing ethical and clinical debate about the use of stimulants for cognitive enhancement in healthy individuals, but this falls outside their approved indications.