CNS stimulantsm(exam3)

What is the general mechanism of action of a CNS Stimulant?

increase the excitability of the CNS

What are the classes of CNS stimulants we discussed in lecture?

• amphetamines

• xanthines (caffeine)

• cocaine

What are the responses observed upon Amphetamines administration.  

• increased alertness, wakefulness, decreased fatigue, mood elevation or euphoria, increased initiative

• DECREASED APPETITE but little effect in reducing food intake if eating for psychological reasons

What is the mechanism of action of Amphetamines?

• increases the release of NE in the brain

  • res[onsible for CNS stimulation

• BUt also, increases dopamine

  • \cause SE

What are the therapeutic uses of Amphetamines?

• ADHD “hyperkinetic” children/adults

• narcolepsy-uncontrollable urge to sleep

• weight control

• scheduled II drugs

What are the side effects / toxic effects of Amphetamines?

• CNS- nervousness, anxiety, sleeplessness

  • high dose-schizophrenic behavior (increase dopamine), hallucinations, paranoia

• cardiovascular- increased HR, BP, poss arrythmias

• WEIGHT LOSS AND MALNUTRITION ( bc it suppresses appetite)

• in hyperkinetic child-sleeplessness, excessive crying

  • suppress growth

    • reversible if quit before bone closure

    • some experts recommend drug holidays (take breaks from taking medication)

• possible but rare bone marrow suppression

  • do periodic blood checks

What are the contraindications Amphetamines?

• insomnia or psychological disorders (suicidal, schizophrenia)

• HTN, cardiac arrythmias

• anorexia

What are the cautions of Amphetamines?

• potential for abuse

  • drug interactions

    • anticholinergics, anticoagulants, anticonvulsants, tricyclic antidepressants

      • usually requires a dosage adjustment

What are the responses observed upon administration Xanthines

• CNS stimulation

  • increased alertness, decreased fatigue

• cardiac stimulant (rate and force of contraction)

• constricts blood vessels in brain

  • coffee may help reduce HA

• diuresis

• BRONCHIORELAXATION

  • requires higher dose than CNS effects.

BRONCHIORELAXATION EFFECT

THEOPHYLINE AND AMINOPHYLINE HAVE A BRONCHIORELAXATION EFFECT that can be used for asthma or other obstructive pulmonary disease

What is the mechanism of action of Xanthines?

• increased breakdown of cyclic AMP

• increases CNS activity

• dilates bronchioles

• dilates pulmonary blood vessels, but constricts cerebral vessels

What are the therapeutic uses of Xanthines ?

• pain from HA

  • c affeine often over the counter

    • conflicting evidence over effectiveness

    • no activity alone

    • but is potentiates of other analgesics

• ASTHMA, BRONCHITIS, EMPHYSEMA

  • aminophyline

• COUNTER DROWSINESS

What are the side effects of Xanthines?

• increases heart rate, cardiac arrythmias

• increased gastric secretion

  • caffeine is the worst of the xanthines

  • diuresis

  • excess CNS stimulation

    • insomnia, convulsions

  • withdrawal sx

What are the contraindications and cautions with Xanthines?

• cardiac arrythmia

• ulcers

• pregnancy

  • birth defects in small animals w/large caffeine doses

  • no birth defects in humans have been noted

What are the responses observed upon Cocaine administration.  

• similar to amphetamines in:

  • responses observed

  • mechanisms of action on CNS

  • many side/toxic effects

  • cautions and contraindications

  (increased alertness, wakefulness, decreased fatigue, mood elevation or euphoria, increased initiative

  DECREASED APPETITE but little effect in reducing food intake if eating for psychological reasons)

• DIFFERENT FROM AMPHETAMINES:

  • not approved by the FDA excepts as a local anesthetic

  • used only in hospital or clinic

    • (procaine, benzocaine, lidocaine)

    • these are not general depressants

What is the mechanism of action of cocaine?

• increases the release of NE in the brain

  • responsible for CNS stimulation

• BUt also, increases dopamine release

-blocks depolarization

What are the side effects of Cocaine?

• CNS

  • early signs of CNS stimulation (anxiety, restlessness, confusion, dizziness, tremors, convulsions)

  • cardiovascular

    • early central stimulation

      • like amphetamines, may begin w/central stimulation causing increased HR, BP

      • later depressant action directly on heart (bradycardia, hypotension, cardiac arrest)

        • different from amphetamines soon see depression

  • Allergic reactions-not common but are possible

  • CORONARY OCCLUSION W/ CHRONIC COCAINE ABUSE