CNS Depressants:Sedative-Hypnotics

Chapter 6

Introduction to CNS DepressantsWhy are CNS depressants problematic?Usually prescribed under physicians directionSecond most frequently abused prescription drug and sometimes contributes to death due to accidental overdosesCan cause very alarming and dangerous behavior if not closely monitored Most problems associated with these drugs due to inadequate professional supervision

Introduction to CNS Depressants (continued) Why are CNS depressants problematic? Seemingly unrelated drug groups can cause CNS depressionCombination use can cause dangerous drug interactionsCan cause disruptive personality changes

The History of CNS DepressantsAttempts to find CNS depressants other than alcohol began in the 1800s.Bromides were introduced to treat nervousness and anxiety in the 1800s.Very popular but toxicIn the early 1900s, bromides were replaced by barbiturates.Initially heralded as safe and effectiveApparent problems with tolerance, dependence, and safety

In the 1950s the first benzodiazepines were marketed as substitutes for barbiturates.Relatively safe when used for short periodsLong-term use can cause dependence and withdrawal problemsThe History of CNS Depressants(continued)

The History of CNS Depressants (continued)Benzodiazepines were routinely prescribed for stress, anxiety, or apprehension.In 1973, 100 million prescriptions were written for benzodiazepines.Twice as many women as men taking them.As medical community became aware of the problem, use of depressants declined, but benzodiazepines remained still very popular.Classified as Schedule V drugs

The Effects of CNS DepressantsCNS depressants reduce CNS activity and diminish the brains level of awareness. Depressant drugs include: Benzodiazepines Barbiturate-like drugs Alcohol Antihistamines Opioid narcotics like heroin

The Effects of CNS Depressants (continued)Depressants are usually classified according to the degree of their medical effects on the body. For example:Sedatives cause mild depression and relaxationAnxiolyticdrugs that relieve anxietyHypnotics induce drowsiness and encourage sleep Amnesiac effects can cause the loss of memory

The Effects of CNS Depressants (continued)The same drug can cause different effects depending on dose.Low dose (sedativesrelieve anxiety and promote relaxation)Higher doses (hypnoticscan cause drowsiness and promote sleep)Even higher doses (anesthetics can cause anesthesia and are used for patient management during surgery)

Types of CNS DepressantsBenzodiazepines: Valium-Type Drugs Prescribed for anxiety, relaxation and sleep Medical uses Relief from anxiety, treatment of neurosis, relaxation of muscles, alleviation of lower-back pain, treatment of convulsive disorders, induction of sleep, relief from withdrawal symptoms, induction of amnesia

BenzodiazepinesLibrium-1960Valium-1972-1978-leading prescription drugToday-Xanax and AtivanSchedule IV

Types of CNS Depressants (continued)Mechanisms of action for benzodiazepineAffect neurons that have receptors for the neurotransmitter GABAGABA: most common inhibitory transmitter in brain regions Limbic system (alter mood) RAS (cause drowsiness) Motor cortex (relax muscles)

Types of CNS Depressants (continued)Types of benzodiazepinesMany benzodiazepine compounds available in the United StatesDistinguished primarily by their duration of action: short-acting (hypnotics), long-acting (sedatives)Side effects include drowsiness to paradoxical effects (e.g. increased restlessness), tolerance, dependence, withdrawal, and abuse

Half Lives

Types of CNS DepressantsLikely that a natural benzodiazepine does existFlumazenil (Romazicon)-antagonist Possible danger-may bring on immediate withdrawal

Types of CNS Depressants (continued)Barbiturates played an important historical role as sedative-hypnotic agents.However, due to their narrow margin of safety and their abuse liability, they were replaced by benzodiazepines.Caused many negative side effects, from nausea to death, from respiratory or cardiovascular depression

Other Types of CNS DepressantsDrugs with barbiturate-like properties:Chloral hydrateGlutethimideMethyprylonMethaqualoneAntihistaminesPropofol (abused general anesthetic)GHB (gamma hydroxybutyrate)

Patterns of Abuse with CNS DepressantsThe American Psychiatric Association considers dependence on CNS depressants a psychiatric disorder.

Patterns of Abuse with CNS Depressants (continued)People most likely to abuse CNS depressants include individuals who:Use drugs to relieve continual stressParadoxically feel euphoria and stimulation from depressantsUse depressants to counteract the unpleasant effects of other drugs of abuseCombine depressants with alcohol and heroin to potentiate the effects

Patterns of Abuse with CNS Depressants (continued)Detoxification: The elimination of a toxic substance, such as a drug, and its effectsWith CNS depressants, this is achieved by substituting a longer-acting barbiturate for the offending CNS depressant and gradually reducing the dose to avoid unpleasant withdrawal effects. Withdrawal from CNS depressants, if not managed properly, can be very dangerous, or even fatal.