What are some of the most common chemical convulsants?
What is the mechanism of action for picrotoxin and pentylenetetrazol?
- Both picrotoxin and pentylenetetrazol are non-competitive inhibitors (may bind to target with or without ligand present) of Cl- channels associated with GABAa receptors.
- This causes disinhibition.
Both ____________ and ____________ are common ingredients found in rat poisons.
Strychnine and picrotoxin
Strychnine poisoning may result in _______________ and/or _______________.
- Risus sardonicus
_____________ is the severe hyperextension and spasticity in which an individual's head, neck, and spinal column enter into a complete "arching" or "bridging" position.
_________________ is the abnormal, sustained spasm of the facial muscles that appears to produce grinning.
What is the usual treatment for strychnine poisoning?
- Treat with diazepam (benzodiazepine)
- Reduce environmental stress
- Administer activated charcoal to deactivate chemical in digestive tract
What are the three common methylxanthines?
Methylxanthines are (man-made/plant products).
On average, there is approximately ___ mg of caffeine in a can of Coca Cola.
What are some of the cognitive effects seen in methylxanthine use?
- Increased capacity for intellectual effort
- Decreased reaction time
- Decreased fine motor coordination
- Decreased timing skills
- Decreased arithmetic skills
Methylxanthines (increase/decrease) the sensitivity of the body's medullary receptors to CO2.
- Increased sensitivity to CO2 causes increased stimulatory inputs to the respiratory center of the brain and increased respiration.
Methylxanthines cause a slight (increase/decrease) in heart rate.
Decrease, though this seems counterintuitive
Methylxanthines (dilate/constrict) peripheral vasculature to muscles, while they (dilate/constrict) cerebral vasculature.
Dilate peripheral vasculature
Constrict cerebral vasculature
Theophylline, a methylxanthine, (dilates/constricts) the bronchioles.
Methylxanthines (increase/decrease) the capacity for work in skeletal muscle.
Coffee, which contains caffeine, (inhibits/stimulates) peristalsis in the GI system.
What is the mechanism of action for methylxanthines?
Methylxanthines primarily function by acting as adenosine receptor antagonists. They also inhibit phosphodiesterases, increasing cyclic AMP and GMP. Lastly, at high concentrations they may cause release of intracellular Ca2+.
(T/F) Most effects of adenosine are the opposite of methylxanthines.
Adenosine (dilates/constricts) peripheral vasculature to muscles, while it (dilates/constricts) cerebral vasculature.
Constricts peripheral vasculature
Dilates cerebral vasculature
Methylxanthines usually experience a peak plasma concentration within ___-___ hours after ingestion.
(T/F) Genetic variability in the enzyme N-acetyltransferase may cause changes in methylxanthine half life.
Half life of methylxanthines may be increased by:
- Liver disease
- Oral contraceptives
Half life of methylxanthines may be decreased by:
- Combination with phenytoin or barbiturates
Caffeine half life in adults is typically ___-___ hours
Caffeine half life in pre-term infants is around ___ hours.
Toxic amounts of caffeine may cause (olfactory/gustatory/both) hallucinations.
Both olfactory and gustatory hallucinations
(Consumption of/Failure to consume) caffeine in non-tolerant individuals may cause headaches.
(Consumption of/Failure to consume) caffeine in tolerant individuals may cause headaches.
Failure to consume
What is the mechanism of action for nicotine?
Nicotine acts as an acetylcholine receptor agonist at Nicotinic Acetylcholine receptors.
What is the mechanism of action for bupropion, a non-nicotine option for tobacco dependence?
Bupropion serves as a catecholamine reuptake inhibitor.
(T/F) Bupropion will only cause hypertension in those with pre-existing hypertensive conditions.
False. Bupropion may cause hypertension in anyone, even those without pre-existing hypertensive conditions.
______________ is a drug used in tobacco-dependent patients that acts as a catecholamine reuptake inhibitor.
What is the mechanism of action for varenicline, a drug used in patients with tobacco dependence?
- Varenicline is a partial agonist at α4β2 nicotinic acetylcholine receptors.
- It acts to blunt the rewarding effects of nicotine.
____________ is a drug useful in patients attempting to decrease tobacco-dependence. It acts as a partial agonist at α4β2 nicotinic acetylcholine receptors, serving to blunt the rewarding effects of nicotine.
What is the mechanism of action of rimonabant, an anti tobacco-dependence drug that was pulled from the market due to its psychiatric effects?
Rimonabant acts as an antagonist/inverse agonist at CB1 cannabinoid receptors.
___________ is a drug that was previously used in tobacco-dependence, but was pulled from the market due to its adverse psychiatric effects. It functions by acting as an antagonist at CB1 cannabinoid receptors.
What are some of the most common psychomotor stimulants in use today?
In the periphery, (L-amphetamine/D-amphetamine) is a more potent substance. This is opposed to the central nervous system, where (L-amphetamine/D-amphetamine) is more potent.
- L-amphetamine in periphery
- D-amphetamine in CNS
How are the psychomotor stimulants ranked according to potency?
- Cocaine and Methylphenidate
Psychomotor stimulants, such as amphetamines, (stimulate/inhibit) the medullary respiratory centers of the brain.
Psychomotor stimulants, such as methamphetamine, (increase/decrease) motor activity.
Psychomotor stimulants, such as cocaine, (depress/elevate) mood.
Psychomotor stimulants, such as methylphenidate, (increase/decrease) sleep.
What is the mechanism of action for amphetamine?
- Causes the release of catecholamines (DA, NE) and 5-HT (serotonin)
- Inhibits reuptake of catecholamines (DA, NE) and 5-HT
What is the mechanism of action for methylphenidate and cocaine?
Inhibit reuptake of monoamines via blockade of transporters
______________ are drugs that cause the release of catecholamines and 5-HT from the presynaptic cell. They then inhibit the reuptake of both catecholamines and 5-HT.
______________ and ______________ are drugs that inhibit the reuptake of monoamines via the blockade of monoamine transporters (MAT) and dopamine transporters (DAT) on the presynaptic cell.
Methylphenidate and Cocaine
What are some of the common clinical uses of psychomotor stimulants?
- Weight loss
Amphetamines have been used as weight control drugs in the past. This is due to their _____________ effect in patients.
- Amphetamines are unique in that they reduce appetite.
_____________ is a non-amphetamine stimulant also used in cases of narcolepsy. Its use is more common in adults than children.
(T/F) High doses of amphetamines and other psychomotor stimulants may be misinterpreted as a manic episode.
False. High doses of amphetamines may be misinterpreted as a schizophrenic reaction.
Psychomotor stimulants may cause (increased/decreased) paranoia.
(T/F) Over time, psychomotor stimulants begin to exhibit reduced binding to NMDA receptors.
False. Over time, psychomotor stimulants begin to exhibit reduced binding to DAT transporters.
What is the mechanism of action for MDMA?
- Releases presynaptic 5-HT
- Also releases norepinephrine and dopamine
Accomplishes this by entering the neuron through monoamine transporters. Once inside, it inhibits VMAT, the repackaging enzyme used to transport monoamines into vesicles for release. This increases the cytoplasmic concentration of monoamines and reverses their respective transporters within the cell.
________________ is a drug that acts to increase extracellular concentrations of serotonin primarily, but also dopamine and norepinephrine. It enters the cell through MATs and inhibits VMAT. This increases cytoplasmic concentration of serotonin, dopamine, and norepinephrine and reverses their transport. It is most often used as a recreational or party drug.
What is the mechanism of action for strychnine?