depressants Flashcards
major inhibitory NT in CNS
GABA
Barbiturates absorption
small intestine
Barbiturates distribution
highly lipid soluble
fast rate of entry into CNS
Barbiturates metabolism
slow
induce hepatic drug-metabolizing enzymes (Rx interactions)
Barbiturates MOA
bind GABA-A receptor
increases duration of channel opening
high conc: directly activate
hella high conc: decrease release of other NTs
Barbiturates effects
CNS depression low therapeutic index hypotension anticonvulsant activity not analgesic reduce REM sleep induce own metabolism
Barbiturates dependence
psychological
physical
status epilepticus
abrupt withdrawal is life-threatening
Methohexital
ultra-short acting BARB
anesthesia
short procedures
Secobarbital
Pentobarbital
short/intermediate acting BARB
sedation
insomnia
Phenobarbital
long acting BARB
epilepsy
Barbiturates SE
CNS depressant
OD: death
contraindicated in acute intermittent porphyria
Barbiturates Rx interactions
additive effects w/CNS depressants
cross-tolerance w/CNS depressants
induction of P450
Ethanol absoprtion
GI tract
Ethanol distribution
cross BBB
cross placenta
Ethanol metabolism
liver
unchanged in urine
sweat
alcohol dehydrogenase
oxidizes ethanol to acetaldehyde
acetaldehyde dehydrogenase
oxidizes acetaldehyde to acetate
Ethanol MOA
dissolves in neuronal embranes
enhances GABA inhibition
inhibits NMDA Glu-ergic
Ethanol effects
CNS depression heat loss (hypothermia) vasodilation depress myocardial contractility stimulates gastric secretions decreases testosterone inhibits ADH secretion
Ethanol dependence
psychological
physical
withdrawal: early awakening, anxiety, tremor, can be life-threatening
delirium tremens
full-blown alcohol withdrawal syndrome
tremors, motor agitation, anxiety, hyperexcitability, hyperactivity, hyperthermia, hallucinations, toxic psychosis, seizures, death
15% chronic users
Tx: diazepam/clonazepam
Ethanol SE
blackouts death by hypothermia peripheral nerve damage cerebellar cortical degeneration macrocytic anemia iron deficiency GI bleeding nutritional deficiencies pancreatitis fatty liver cirrhosis 15% slow metabolism of other drugs
Wernicke-Korsakoff syndrome
alcoholic encephalopathy
thiamine deficiency
confusion, abnormal ocular motility, ataxia, polyneuropathy, learning/memory problems
fetal alcohol syndrome
deformities of face/head (midline), hydrocephaly, holoprosencephaly, prenatal growth deficiency, postnatal growth deficiency
Ethanol Rx interactions
additive effect
acute: inhibit metabolism of other drugs
chronic: increase rate of drug metabolism
Ethanol Tx
1) detoxification
2) abstinence
Disulfiram
inhibits acetaldehyde dehydrogenase
Methanol
acidosis, optic nerve damage, blindness
Tx: sodium bicarbonate, ethanol
alcohol dehydrogenase
0th order kinetics
