10 Questions
What is the primary design focus of most immunoassays?
Codeine and morphine
What is the reason for cross-reactivity in immunoassays?
Similarities in chemical structure
What is the basis of classification for barbiturates?
Length of time they exert their pharmacologic effects
What is the typical example of a long-acting barbiturate?
Phenobarbital
What is the effect of barbiturates on neuronal membranes?
They stabilize them
Why do barbiturates pass easily through the blood-brain barrier?
They are fat-soluble
What is the prototype drug for short-acting barbiturates?
Pentobarbital
What is the prototype drug for ultrashort-acting barbiturates?
Thiopental
What is the effect of barbiturates on seizure activity?
They are highly effective against it
What is the purpose of GC/MS in the context of opiates?
Confirmation testing
Study Notes
Toxicology of Alcohols and Other Substances
Methanol
- Also known as wood alcohol, commonly used as a solvent in the laboratory
- Metabolized into formaldehyde and formic acid through the enzyme ADH
- Increased formic acid can lead to acidosis and fatal outcomes
- Symptoms of intoxication include blindness, metabolic acidosis, and neuropathic symptoms
- Screening test: osmolal gap, preferred method is GC-MS
- Toxic blood level: >50 mg/dL, fatal dose: 60-250 mL
Isopropanol
- Also known as rubbing alcohol
- Rapid absorption in the GIT
- Metabolized into acetone in the liver
- Symptoms of intoxication include CNS depression, HTN
- Indication of toxicity: increased acetone in urine and blood
- GC is the preferred method, fatal dose: >250 mL
- Antidote: activated charcoal
Ethylene-Glycol
- Found in hydraulic fluid and anti-freeze substances
- Tastes sweet, commonly ingested by children
- Metabolized into toxic compounds, leading to acidosis and kidney damage
- Screening test: GC-MS, preferred method is GC
Other Substances
LSD
- Provides new insights and new ways of solving problems
- Visual effects are more intense
- Panic reactions like suicide or "bad trip" are most common adverse reactions
- Routes of administration: intravenous, oral
- Half-life: 5.1 hours
- Testing: urine sample, screening procedure is Ehrlich spot test, confirmation testing is LC/MS-MS
Opiates
- Derived from or chemically related to substances from the opium poppy
- Capable of analgesia, sedation, and anesthesia
- High abuse potential, chronic use leads to tolerance and physical and psychological dependence
- Acute overdose presents with respiratory acidosis, myoglobinuria, and possibly an increase in serum indicators of cardiac damage
- Treatment of overdose includes the use of the opiate antagonist naloxone
- Screening procedure: immunoassay, confirmation testing: GC/MS
Barbiturates
- Derivatives of barbituric acid
- Classified into long-acting, short-acting, ultrashort-acting, and intermediate-acting barbiturates
- All barbiturates are fat-soluble and can pass easily through the blood-brain barrier
- Can stabilize membranes, making depolarization of neuronal membranes difficult
Learn about methanol, also known as wood alcohol, its uses in the laboratory, and its toxic effects on the human body. Understand how it is metabolized and the symptoms of intoxication, including blindness and acidosis.
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