5. Substance-related disorders Flashcards
What is the lifetime prevalence of substance abuse or dependence in the US?
17%
How do you test for alcohol?
Blood/urine test
How long does alcohol stay in the system?
only a few hours
How long is urine tox positive for cocaine?
2-4 days
How long is urine tox positive for amphetamines?
1-3 days
How long is urine tox positive for PCP?
3-8 days
What other lab values are also elevated in PCP use? (2)
CPK and AST
How long is short acting barbiturate (pentobarbital) in the blood/urine?
24 hrs
How long is long acting barbiturate (phenobarbital) in the blood/urine?
3 wks
How long is short acting benzo (lorazepam) in the blood/urine?
3 days
How long is long acting barbiturate (diazepam) in the blood/urine?
30 days
Which opioids come up negative on a general screen? (2)
methadone, oxycodone
How long is urine tox positive for SINGLE marijuana use?
3 days
Why is urine + for chronic marijuana users for up to 4 wks?
THC is released from adipose stores
How does alcohol work in terms of binding sites/receptors? (4)
- activates GABA
- activates serotonin receptors
- inhibits glutamate receptors
- inhibits voltage-gated calcium channels
What is the lifetime prevalence of alcohol dependence in US for women and men?
3-5% women
10% men
What is the alcohol metabolism?
Alcohol –> acetaldehyde –> acetic acid
What are the 2 enzymes involved in metabolism of alcohol?
Alcohol dehydrogenase
Aldehyde dehydrogenase
Why are Asians less tolerant to alcohol?
Have less aldehyde dehydrogenase
- results in flushing and nausea
- protecting against alcohol dependence
What is the most common co-ingestant in drug overdose?
Alcohol
At what BAL do you start seeing signs of intoxication?
BAL > 100
What is the tx for alcohol withdrawal?
Benzodiazepine taper
- usually chlordiazepoxide (Librium) considered drug of choice
Signs and symptoms of mild alcohol withdrawal syndrome? (3)
irritability, tremor, insomnia
Signs and symptoms of moderate alcohol withdrawal syndrome? (5)
diaphoresis, htn, tachycardia, fever, disorientation
Signs and symptoms of severe alcohol withdrawal syndrome? (3)
tonic-clonic seizures, DTs, hallucinations
When does EtOH withdrawal syndrome begin, and how long does it last?
begin in 6-24 hrs
lasts 2-7 days
What electrolyte abnormality can predispose to EtOH withdrawal seizures?
hypomagnesemia
What are seizures in EtOH withdrawal syndrome treated with?
Benzodiazepines
What % of patients hospitalized for EtOH withdrawal develop DTs?
5%
When does DTs usually begin?
48-72 hrs after last drink, but can occur later
90% of cases within 7 days
Prevalence of DTs in men vs. women
Men develop DTs 4-5x more
What are some symptoms of delirium tremens? (6)
Seizures
Delirium
Hallucinations (most commonly visual; also tactile)
Gross tremor
Autonomic instability (increased RR, HR, BP)
What can be used to treat DT? (2)
Benzodiazepines
Dilantin (phenytoin) - anticonvulsant
In addition to benzo taper, what else can be used to treat alcohol withdrawal? (2)
Carbamazepine or VPA taper
What are the medications indicated for alcohol dependence? (4)
- Disulfiram (Antabuse)
- Naltrexone (Revia, IM-Vivitrol)
- Acamprosate (Campral)
- Topiramate (Topamax)
What MCV (mean corpuscular volume) changes are seen in alcohol dependence?
macrocytosis (increased MCV)
How does disulfiram work?
Blocks aldehyde dehydrogenase in the liver –> causes aversive rxn to alcohol (flushing, headaches, nausea/vomiting, palpitations, SOB)
Who are disulfiram best for?
Highly motivated pts (better medication adherence)
How does Naltrexone work?
Blocks opioid receptor
- works by decreasing desire/craving and “high” associated with alcohol
Greatest benefit of Natrexone seen in which patients?
pts w/ family hx of alcoholism
How does Acamprosate work?
structurally similar to GABA
- thought to inhibit glutamatergic system
What is Acamprosate indicated for?
Post-detox for relapse prevention in pts who have stopped drinking
What is the major advantage of Acamprosate?
can use in pts with liver disease
Contraindication of Acamprosate?
pts with severe renal disease
Mechanism of Topiramate in tx of alcohol dependence?
Anticonvulsant that potentiates GABA –> inhibits glutamate receptors
- reduces cravings for alcohol
Tx for Wernicke’s encephalopathy?
THIAMINE tx! (before giving glucose)
What are features of Wernicke’s encephalopathy? (3)
- Ataxia
- Confusion
- Ocular abnormalities (nystagmus, gaze palsies)
What is Korsakoff syndrome?
Chronic amnestic syndrome = impaired recent memory, anterograde amnesia, compensatory confabulation
What % of pts can be reversed from Korsakoff syndrome?
Reversible in only 20% of pts
What is the mechanism of cocaine?
blocks pre-synaptic DA reuptake transporter –> increases DA signalling –> increases “reward” system
General intoxication symptoms of cocaine? (not dangerous)
euphoria, heightened self-esteem, change in BP, tachy or brady, nausea, DILATED pupils, weight loss, psychomotor agitation/depression, chills, sweating