Chapter 3 CNS - psychomotor stimulants

Question 1

Why CNS stimulants prescirbed to hyperkinetic children?

Answer 1

• studies showed that amphetamine can accelrate bx which is slow in the absence of drug and suppress rapid bx patterns
• essentially it can induce “slow-rate” behavior in children with attention deficit disorder, which can account for improved learning and memory skills

Question 2

Attention decific disorder (ADD)

Answer 2

• children

characterized w/:
* short attention span
* restlessness
* distractibility
* impulsivity
* emotional lability
* hyperacitivity is sometimes associated

• amphetamine-like drugs can reduce sx’s in >80% of affected children
• also may include family counseling and/or psychotherapy
• therapy is tailored around school schedule
• drug therapy OFTEN d/c’d during school vacations

Question 3

d-Amphetamine (adderall)
Methylphenidate (ritalin)
dexmethylphenidate (focalin)

amphetamine-like drugs

Answer 3

• release NE, D, 5-HT from storage vesicles
• CNS stimulant… decrease appetite
• improves ability of athletes + coordination / performance of fatigued subjects
• increase BP

indication:
* narcolepsy (chronic neurological disorder that affects the brain’s ability to control sleep-wake cycles. People with narcolepsy may feel rested after waking, but then feel very sleepy throughout much of the day)
* attention deficit d/o in children
* no longer recommended for obesity

effects
* CNS overstimulation
* restlessness
* dizziness
* insomnia
* increased BP
* arrhythmia
* anorexia (appetite suppressant => d-amphetamine)
* psychotic episodes

PO // enters CNS & leaves sys w/o undergoing metabolism

Methamphetamine (speed)…

Drug interactions
1) MAO — HTN crisis, CNS overstimulation
2) Barbiturates — supraadditive mood elevation
3) Tricyclic antidepressants — potentiate CNS stimulation while inhibiting metabolism of amphetamine

OVERDOSE TX
* acidify urine
* give chlorpromazine (antipsychotic) to tx CNS sx’s
* give alpha-receptor blocker to lower BP

Question 4

Lisdexamfetamine (vyvanse)

amphetamine-like drugs

Answer 4

• pro-drug for d-amphetmaine (need to be activated by liver via metabolism, prior to that this drug is considered INACTIVE ==> pharmacokinetics)

indication
* narcolepsy (chronic neurological disorder that affects the brain’s ability to control sleep-wake cycles. People with narcolepsy may feel rested after waking, but then feel very sleepy throughout much of the day)
* attention deficit d/o in children
* no longer recommended for obesity

effects
* CNS overstimulation
* restlessness
* dizziness
* insomnia
* increased BP
* arrhythmia
* anorexia
* psychotic episodes

can be abused

Drug interactions
1) MAO — HTN crisis, CNS overstimulation
2) Barbiturates — supraadditive mood elevation
3) Tricyclic antidepressants — potentiate CNS stimulation while inhibiting metabolism of amphetamine

Question 5

Pemoline (cylert)

amphetamine-like drugs

Answer 5

• mild CNS stimulant
• actions similar to d-amphetamine

indication:
attention deficit disorder

effect
* insomnia
* anorexia
* liver dysfunction (usually reversible)

PO // daily administration

Low abuse potential

Drug interactions
1) MAO — HTN crisis, CNS overstimulation
2) Barbiturates — supraadditive mood elevation
3) Tricyclic antidepressants — potentiate CNS stimulation while inhibiting metabolism of amphetamine

ONSET of therapeutic actions begin after 3-4 wks of tx

Question 6

Caffeine

methylated xantines

Answer 6

• adenosine receptor antagonist (arousal, locomotion, regulation of cardiac contractility, vascular tone, adipocyte fat content, diuresis, and the immune response)
• FOR HIGH dose - inc’d Ca++ permeability in SR and inc’d cAMP by inhibiting phosphodiesterase
• stimulates CNS, constricts cerebral arterioles, induces diuresis (urine)
• simulates heart
• bronchodilates

When adenosine binds to its receptors, neural activity slows down, and you feel sleepy. Adenosine thus facilitates sleep and dilates the blood vessels, probably to ensure good oxygenation during sleep. Caffeine acts as an adenosine-receptor antagonist.

indications
* prolonged apnea (preterm baby)
* included in headache remedies (OTC analgesic prep){

effects
* insomnia
* restlessness
* anxiety neurosis
* nausea
* tachycardia
* diuresis

PO/IM/IV // rapid absorption and can cross placenta

tolerance and dependence likely! withdrawal may cause headache, anxiety, and muscle tension

1) oral contraceptives and cimetidine (antihistamine and antacid for ulcers) ==> inhibits metabolism
2) smoking enhances elimination

&&&&&&&&

85 mg caffeine per cup coffee while 50 mg/cup of tea or cola

Question 7

Theophylline

methylated xantines

Answer 7

• cellular mechanism of caffiene
• more CNS stimulation than caffeine
• increased cardiac stimulation and diuresis
• more effective bronchodilator

msut be maintained between 10 - 20 ug/ml b/c it is ineffective at lower concentrations and it produces undesirable effects at higher dose

indications:
* bronchial asthma
* apnea and bradycardia in premature infants

effects
* insomnia
* restlessness
* anxiety neurosis
* nausea
* tachycardia
* diuresis

PO

tolerance and dependence likely! withdrawal may cause headache, anxiety, and muscle tension

1) oral contraceptives and cimetidine (antihistamine and antacid for ulcers) ==> inhibits metabolism
2) smoking enhances elimination

&&&&&&&

overall use decreasing d/t toxicity and questionable efficiency

Question 8

Atomoxetine (strattera)

norepinephrine uptake inhibitors

Answer 8

• selectively inhibits norepinephrine uptake

indication:
* attention deficit disorder

effect
* suicide risk
* serious CV effects
* heart rate inc

PO / enters CNS

low abuse potential

drug inter.
* MAO inhibitors (HTN crisis, CNS overstimulation)