CNS Depressant Drugs

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CNS Depressant Drugs

• Sedatives, Hypnotics, Inhalants
• . . . and Alcohol . . . Alcohol treated in a
  Separate Chapter

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CNS Depressants a.k.a. Sedative-Hypnotics

• Also called downers, anxiolytics, sleeping
  pills, relaxants.
• Includes several chemical classes
• Common, widespread, effect on CNS can be summed
  up as decreased neural activity.

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Dose-related Variability in Effects
Sedative vs. Hypnotic

• LOW Doses Sedatives --Prescribed in daytime
  for anxiety (a.k.a. anxiolytics)
• HIGH Doses Hypnotics --Prescribed at night for
  insomnia (a.k.a. sleeping pills)

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Clinical Uses Limitations
Rapid tolerance develops, therefore . . . CNS
depressants should be used only for short periods
of time!

• Tx for occasional not chronic insomnia
• Tx for acute not chronic anxiety
• One exception . . . .

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. . . Seizure Disorder is an Exception

• Tx for chronic seizure disorder (epilepsy).
• Needs to be treated long term, 24-7-365 with an
  effective anticonvulsant But rapid tolerance
  develops to depressant meds, therefore . . .
• Recalibration is needed as tolerance develops.
  May even need to change meds occasionally.
• drowsiness when dose is too high
• seizure may occur when dose is too low,or upon
  withdrawal

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Classification by Duration of EffectsShort-actin
g vs. Long-acting

• Ultra short-acting -- 15 min. to 3 hours Med Tx
  anesthetic induction
• Short-acting -- 3 to 6 hoursMed Tx sleep aid
  (hypnotic), pre-surgical sedative, emergency
  seizure control
• Intermediate-acting -- 6 to 12 hours Med Tx
  all-day sedative for anxiety!
• Long-acting -- 12 to 24 hoursMed Tx
  anticonvulsant, or all-day sedative

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Clinical Uses of Sedatives

• Short-Acting Sedatives
• Insomnia
• Acute alcohol withdrawal (prescribed or
  self-medication)
• Pre-anesthetic drug(anesthetic induction).

• Long-Acting Sedatives
• Epilepsy / Seizure
• Anxiety disorders (phobia, panic attack,
  obsessive compulsive disorder, etc.)
• Muscle Relaxants to reduce painful muscle spasms.

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CNS Effects

• Depression of the CNS, ranging from mild
  sedation to coma, or even death.
• Degree of CNS depression related to
• type of drug
• dose
• route of administration
• expectations
• condition of patient/user

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Depressants Patterns of Abuse

• Intoxication is qualitatively similar to being
  drunk on alcohol. Especially true
  withshort-acting sedatives in larger doses.
• 4 basic patterns of abuse
• Elderly accidental related to sleeping pills.
  
• Middle-Age - accidental anti-anxiety
• Young users --intentional combined w/ alcohol for
  quicker intoxication
• Deviant sexual predation --planned criminal
  sexual assault upon another human being.

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Types of Sedatives

• 2 main classes used clinically
• Benzodiazepines--safer clinically
• Barbiturates--more bang more abused
• Of the 2 types, barbiturates are more potent and
  have greater potential for abuse and related
  problems.

Bang !
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Benzodiazepine Sedatives

• Well-known Benzos
• Valium diazepam
• Xanax alprazolam
• Librium chlordiazepoxide

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Anxiety, Sedation, Sleep

• Ativan
• Rohypnol
• Klonopin
• Tranxene
• Sonata
• Mylostan

• Serax
• Dalmane
• Restoril
• Halcion
• Ambien
• Lunesta

Muscle Relaxant, Anticonvulsant
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Benzodiazepine Action

• Most prescribed class of drugs
• Safer than barbiturates
• Slightly different NT actionthan barbiturates
• Enhance the action of GABA
• Bind near GABA sites
• GABA is an inhibitory NT therefore calms CNS
• Benzos cause more GABA activity than normal,
  resulting in sedation.

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Physical Side EffectsParasympathetic Branch of
Autonomic NS

• Reduced breathing rate
• Hypotension ( BP)
• Bradycardia (slow )
• Depressed gag reflex

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Other Serious Side Effects

• CNS drowsiness, ataxia, depression, slurred
  speech, dizziness, impaired vision, confusion,
  amnesia, sleep disturbances, coma, or death
• CV cardiovascular emergency, dysrythmia
• GI nausea

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Behavioral Toxicity

• Behavioral toxicity from sedatives VERY
  similar to alcohol intoxication!!Impaired
  judgment, poor coordination, loss of inhibition,
  tendency toward violence, euphoria, sexual
  arousal etc.

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Dependence Potential

• Potential for both physical psychological
  dependence with powerful depressants.
• Major considerations (1) type of drug, (2) dose,
  and (3) duration of effect/ time course.

The Bigger, Quicker Bang . . . the more potential
for dependence!
Short-acting Types cause a quicker, more intense
effect
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Dependence Duration of Effects

• SHORT-ACTING depressants (quick, but short
  duration) result in a bigger bang and therefore
  are much worse than longer-acting (slower)
  depressants . Increased potential for
  dependence! More severe withdrawal.

Bigger Bang . . . but doesnt last long!
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Withdrawal Danger from Sedatives

• Withdrawal symptoms
• Increased anxiety, insomnia, tremors, confusion,
  hallucinations
• Seizures 2-3 days following
• 5 die from abrupt withdrawal

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Physiological Toxicity !

• Sedative abuse can be deadly
• Decrease in respiratory rate
• May stop breathing entirely!
• Especially dangerous combined w/
  alcohol ALCOHOL Sedatives possible death
• Sudden withdrawal from sedatives may result in
  seizure/convulsions. This can also be deadly.
• Gradual, clinical detox is advised.

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Intentional or Accidental Danger