Pharmacology Unit 6 Lectures 3, 4, and 5

CNS depressant

agents which decreases the excitability of the tissue in the CNS

-produces sedation, hypnosis, general anesthesia, and possibly death.

-act as sedatives, hypnotics, or general anesthetics

sedatives

drugs administered at a dose level to cause mild drowsiness or sedation or to reduce restlessness or anxiety.

hypnotics

drugs administered at a dose level to induce sleep or allow an individual to stay asleep.

Usual dosage range is 3-4 times of the sedative

A person can be aroused from sleep

common types of depressants

benzodiazephines

barbiturates

non-benzodiazepine sleep medications

opoids

alcohol

therapeutic uses CNS depressants

balancing their sedative effects with their potential for abuse, dependency, and adverse effects

general anesthetics

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

-perception of and reaction to pain

analgesic

drug that relieves pain without a loss of consciousness

sedative hypnotic agents

-oldest, largest, and most studied class of the CNS drugs

-drugs have varying degrees of CNS depression depending on the dose administered

-produce generalized depression of the cellular activity of many organ systems as well as the tissue within the CNS

-synapse is the site of action

drug classes of sedative hypnotic agents

barbiturates, benzodiazepines, alcohol, and antihistamines

sedative hypnotic agents therapeutic use

relieves anxiety (situational and neuronic anxiety)

sleep disorders that are temporary since its considered highly abused

-anticonvulsant

epilepsy is a mjor therapeutic reason to use___over benzodiazepines

barbiturates (fill in the blank)

barbiturates MOA

enhance GABA responses and mimic GABA by opening chloride channels in the absence of GABA, increasing inhibition in the CNS

1) produce sedation, hypnosis, and coma, and death

2) suppress respiration (overdoses can lead to death)

3) induce the liver P-450 system (there is a long list of interactions)

-suppress respiration by inhibiting the hypoxic and CO2 responses of the chemoreceptors

-classified by the duration of action (short or long) and degree of lipid solubility

examples of barbiturates

phenobarbital

secobarbital and pentobarbital

thiopental

phenobarbital

slow, onset, long acting (all day)

broadest spectrum of use medically

secobarbital and pentobarbital

intermediate acting (2-4 hours)

thiopental

short acting (onset in seconds, duration i minutes)

given IV

benzodiazepines MOA

benzos 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

True

Most benzos are metabolized in the liver to activate metabolites. The metabolites have___elimination rates than the parent compound.

slower (fill in the blank)

withdrawal of benzos can cause…

confusion, anxiety, agitation, and restlessness

side effects of benzodiazepines

drowsiness

impaired performance or decreased perception and judgment

-including psychomotor activity

-often EEG observed with long term use

-Hangover effect: dizziness, fatigue, and diarrhea

-hyperalgesia (barbiturates only)

overdose: respiratory depression

cautions with benzodiazepines

additive with others of sedative-hypnotic group

drug abuse and habituation

withdrawal state

alcohol during pregnancy

overdose of sedation/hypnotics

respiratory depression (main cause)

-barbiturates suppress depression by inhibiting hypoxic and CO2 responses of the chemoreceptors.

-benzos are less likely to be fatal in overdose if used alone. But ONLY if no other depressant is involved (alcohol and antihistamines)

flumazenil

competitive antagonist for benzos and can be used in cases of overdose or after spinal anesthesia.

alcohol during pregnancy

as little as 2 ounces of alcohol daily during pregnancy increases chances of having a child with birth defects

women who have 3+ drinks daily are at 2-3 times the risk of aborting the fetus as women having <1 drink per day

Drinking 2x/week increases the risk of miscarriage

fetal alcohol syndrome is possible

goals of anesthesia

analgesia: inability to feel pain

loss of consciousness

muscle relaxation

types of anesthesia

inhalation

intravenous

inhalation anesthetics

work too rapidly to see all of the stages

toxic because it depress respiration, lower blood pressure, and decrease heart rate

-arrythmias

nausea and vomiting

which is an intravenous anesthetic, but NOT a depressant?

ketamine

Is thiopental (barbiturate) a depressant?

Yes

General anesthetics are administered by___or___, allowing for control of the dosage and timing of the action

intravenous; intravenous injection (fill in the blank)

Stage 1 of General Anesthesia

Loss of pain: The patient loses general sensation but may be awake. This stage proceeds until the patient loses consciousness

Stage 2 of General Anesthetic

Excitement and hyperactivity: The patient may be delirious (very excited) and try to resist treatment. Heart rate and breathing become irregular and blood pressure will increase

Stage 3 of General Anesthetic

surgical anesthesia: skeletal muscles become relaxed and delirium stabilizes. Eye movements slow and the patient becomes still. Surgery begins here and remains until procedure ends.

Stage 4 of General Anesthesia

Paralysis of the medulla region in the brain (responsible for controlling respiratory and cardiovascular activity)

If breathing or the heart stops, death could result.