Central Nervous System Drugs- Ch. 14

Central Nervous System Drugs- Ch. 14

1. Slows neuronal activity in the brain.

2. Alters epinephrine and norepinephrine

3. Continuum ranging from relaxation, to sedation, to anesthesia

   • Sedatives: Relaxes the patient
     • Hypnotics: Induces sleep in the patient
       • Sedative-hypnotic: Calms at lower doses, causes sleep at higher doses
         • Tranquilizers: Produces a calm or tranquil feeling
   • Withdrawal can cause fever; psychosis; seizures; tachycardia; hypotension; anorexia; muscle cramps; memory, concentration, and orientation impairment; abnormal sounds in the ear; blurred vision; and insomnia, agitation, and anxiety
     • Obvious symptoms last 2-4 wks; subtle can last months

4. Antidepressants

   • Treats GAD, OCD, panic, social phobia, and PTSD
   • Can reduce the negative thoughts associated w/anticipatory component of panic
     • Can also suppress ANS, helping pt. remain calm
   • SSRIs: Safer and w/less sympathomimetic & anticholinergic effects
     • Atypicals, including SNRIs: Side effects include abnormal dreams, sweating, constipation, dry mouth, anorexia, weight loss, tremor, abnormal vision, and loss of sexual desire
       • TCAs: Annoying anticholinergic effects, such as dry mouth, blurred vision, urine retention, and hypertension
         • Not recommended for pt. with a history of heart attack,heart blocks, or arrhythmia.
           • Most are pregnancy category C or D
             • Alcohol or other CNS depressants are off limtis
               • Pt. w/ asthma, GI disorders, alcoholism, schizophrenia, or bipolar should be cautious
         • MAOIs: Can cause orthostatic hypotension, headache, and diarrhea,
           • Pt. should strictly avoid foods containing tyramine
             • Potentiate effects of insulin & other diabetic drugs
             • Rarely used due to potential for severe adverse effects

5. Benzodiazepines

   • Most widely prescribed in medicine
     • Act by binding to GABA receptor-chloride channel molecule, which intensifies effects of GABA
       • Most are metabolized in liver & excreted in urine
         • Does not cause life-threatening respiratory depression unless taken in large quantities, combined w/other CNS depressions, or given to pt. w/sleep apnea.
           • Shortens length of time to get to sleep and reduces frequency of interrupted sleep
             • Most increase total sleep time, btut some reduce stage 3 and some affect REM
             • Can be used for seizure disorders (Valium), alcohol withdrawal, central muscle relaxation, and general anesthesia.
               • Many of these have the same actions and adverse effects, and differ primarily in onset and duration of action.
     • Preferred for short term treatment of insomnia caused by anxiety.
       • Class IV drugs

6. Barbiturates

   • Treatment of choice for anxiety and insomnia prior to introduction of benzos
     • Rarely, if ever, given for anxiety or insomnia anymore b/c of significant adverse effects and better medications
       • Risk of dependence is high; withdrawal is severe and sometimes fatal; OD can cause profound respiratory depression, hypotension, and shock
         • Several are class II
         • Bind to GABA receptor-chloride channel and intensify effects of GABA
           • Capable of depressing CNS function at all levels
             • When taken for prolonged periods, they stimulate microsomal enzymes.
               • Simulates their own metabolism, as well as that of hundreds of other drugs
               • Tolerance can develop to this drug and to other CNS depressants, such as opioids.

7. Miscellaneous

   • Used mainly for social anxiety:
     • Valproate (Depakote)
       • Propranolol (Inderal) and atenolol (Tenormin)
   • Used mainly for insomnia:
     • Zaleplon (Sonata)
       • Eszopiclone (Lunesta)
         • Zolpiden (Ambien)
           • Anxiolytic & hypnotic effect
         • Hypnotic effect
   • Buspirone (BuSpar):
     • Mechanism unclear, but r/t D2 dopamine receptors in brain
       • Agonist effects on presynaptic dopamine & high affinity for serotonin
         • Less likely than benzos to affect cognitive & motor performance
           • Rarely interacts w/other CNS depressants
             • Common side effects: Dizziness, headache, and drowsiness
               • Less of a chance of dependence. May take a couple weeks to work.
                 • Anxiolytic effect
   • Zolpidem (Ambien, Edluar, Intermezzo):
     • Class IV, short-term insomnia treatment
       • Highly specific to GABA
         • Produces muscle relaxation and anti-convulsant effects when given higher than therapeutic dose
           • Rapid onset
             • Impaired liver or kidney will increase serum lvl of drug
               • Use w/ caution in suicidal patients b/c intentional overdose can happen.
                 • Adverse effects may include nausea, dizziness, diarrhea, daytime drowsiness, amnesia, and somnambulism
                   • Rebound insomnia can occur when discontinued
                     • Long-term use allowed
   • Escopiclone (Lunesta)
     • Similar properties to zolpidem
       • Longer elimination half life may give it an advantage over zolpidem in maintaining sleep & decreasing early morning waking
         • More likely to cause daytime sedation
   • Zaleplon (Sonata)
     • Useful for ppl who fall asleep but wake early in the morning
       • Sometimes used for travel
   • Ramelton (Rozerem)
     • Melatonin receptior agonist
       • Shown to improve sleep induction
         • Short onset of action, lasts as long as XR zolpidem
           • Long-term use allowed
             • Hypnotic effect
   • Tasimelteon (Hetlioz
     • Melatonin receptor agonist
       • Treatment of non-24 hour sleep-wake disorder
         • Most common effects are headaches and uncommon dreams
           • Avoid concurrent use w/ fluvoxamine (Luvox) or rifampin (Rifandin)
             • Long-term use allowed