CNS depressants (exam 3)

SEDATIVE

cause mild drowsiness or sedation or to reduce restlessness or anxiety

• should not interfere with the persons ability to function normally

hypnotics

induce sleep or allow an individual to stay asleep

• usually given at higher doses

• by definition a person can be aroused from sleep

general anesthetic

a drug given at a dose to depress the CNS to a degree that causes loss of consciousness (unarousable sleep) as well as analgesia

• person is unarousable

• abolishes perception of and reaction to pain

sedative hypnotic agents

• barbiturates

• benzodiazepines

• alcohol

• antihistamines (stimulant in brain can see a CNS depression)

therapeutic use for sedative/hypnotics

• relives anxiety (most common)

• sleep disorders

• anticonvulsant (epilepsy)

  • epilepsy is a major therapeutic reason to use barbiturates

What are the responses observed upon barbiturates administration?

• produce sedation, hypnosis and coma and death

• suppress respiration (OD can lead to death)

• induce the liver p450 by inhibiting the hypoxic and CO2 responses of the chemoreceptors

• they are classified by the duration of action

What are the therapeutic use of barbiturates and benzodiazepines?

• relieve anxiety

• sleep disorders

• anticonvulsant (epilepsy)BARBITURATES

What are the side and toxic effects and special cautions of BARBITURATES AND BENZODIAZEPINES and ALCOHOL?

• drowsiness

• impaired performance or decreased perception and judgement

• hangover effect: dizziness,fatigue, diarrhea,

• HYPERALGESIA (hypersensitivity of pain) BARBITURATES ONLY

• overdose- resp depression. BARBITURATES BUT CAN BE TRUE OF ANY DEPRESSANT IN COMBO

CAUTIONS FOR SEDATIVES/HYPNOTICS (benzo/diazepines/ALCOHOL)

• additive w/others of sedative hypnotic group

• drug abuse and habituation

  • addiction occurs with daily use for 2 months

    • all sedative hypnotics are ADDICTIVE

    • non barbiturates have no advantages over barbiturates

• withdrawal state (most severe sx possible)

  • mild restlessness, insomnia

  • severe anorexia, nausea, vomiting, hypotension, hallucinations, seizures, convulsions, death

    • take off drugs slowly-sx can last up to 6 weeks or longer. usually only 2 weeks.

• alcohol during pregnancy

  • very serious

OD of sedative/hypnotics (barbiturates, benzo, alcohol)

• resp depression

• barbiturates suppress respiration by inhibiting the hypoxic and CO2 responses of the chemoreceptors

• Benzos are less likely to be fatal in OD is used alone. But ONLY if no other depressant is involved (including alcohol and antihistamines)

• Flumanezil (romazicon) is a competitive antagonist and can be used in cases of OD of Benzos!

barbiturates MOA

• enhance GABA responses and mimic GABA by opening chloride channels in the absence of GABA increasing the inhibition in the CNS. THEY DIRECTLY ACTIVATE THE GABA RECEPTOR EVEN IN THE ABSENCE OF GABA-REASON WHY THERE IS A GREATER RISK OF OD

  • produce sedation, hypnosis and coma, and death

  • suppress resp (OD can lead to death)

  • induce the liver P-450 system

  • they suppress resp by inhibiting the hypoxic and CO2 responses of the chemoreceptors

  • They are classified by the duration of action (short or long) and degree of lipid solubility

BENZODIAZEPINE MOA

GABA HAS TO BE PRESENT

BENZO bind to a specific site enhancing the affinity of GABA receptors for GABA, increasing the frequent opening of chloride channels causing hyperpolarization and increased inhibition of the CNS

• all benzos reduce anxiety and produce sedation. Some benzos are used to treat epilepsy and some are used to induce anesthesia

• most benzos are metabolized in the liver to active metabolites. The metabolites have slower elimination rates than the parent compound

• physical and psychological dependance can occur

• withdrawal of benzos can cause confusion, anxiety, agitation, and restlessness

Goals of general anesthesia

1. analgesia

2. loss of consciousness

3. muscle relaxation

   types of anesthesia: Inhalation, Intravenous