5.04 Depressants (Types, Intoxication, and Withdrawal)

Psychiatry review for the USMLE Step 1 exam.

• Depressants decrease neuronal activity in the brain.
• They can work by stimulating GABAergic neurons or binding to opiate receptors.
• Common GABA-promoting depressants: alcohol, benzodiazepines, barbiturates, and inhalants.
• Opioid depressants include heroin and morphine derivatives.
• Alcohol enhances GABA receptor effects, inhibits glutamate activity, and causes intoxication symptoms such as disinhibition, slurred speech, impaired motor control, lethargy, respiratory depression, and coma.
• Alcohol withdrawal symptoms include anxiety, agitation, insomnia, nausea/vomiting, tremors, autonomic dysfunction, seizures, and can be life-threatening (delirium tremens).
• Benzodiazepines bind to the benzodiazepine receptor, enhance GABA effects, and cause intoxication symptoms similar to alcohol.
• Benzodiazepine withdrawal symptoms include anxiety, agitation, insomnia, and seizures, which are treated with a gradual tapering of the drug.
• Inhalants depress brain activity and cause symptoms such as disinhibition, paranoia, lethargy, dizziness, ataxia, slurred speech, and high doses can lead to respiratory depression and brain damage.
• Opioids bind to opioid receptors, reduce pain, improve mood, and cause intoxication symptoms like drowsiness, constricted pupils, seizures, and respiratory depression.
• Opioid overdose can be reversed with naloxone, an opioid receptor antagonist.
• Opioid withdrawal symptoms include dysphoria, anxiety, weakness, sweating, dilated pupils, and diarrhea, and can be managed with medications like methadone and buprenorphine.
• Alcohol withdrawal is an emergency and requires prompt treatment with benzodiazepines.