Anticonvulsants Part 3 (Convulsants, Stimulants) Flashcards
Name the 3 convulsants
- pentylenetetrazole (Metrazole)
- strychnine
- picrotoxin
Which of the 3 convulsants blocks GABA receptors
picrotoxin
Which of the 3 convulsants decreases neuronal recovery time by increasing K permeability
pentylenetetrazole (Metrazole)
Define the action of strychnine
blocks glycine receptors on Renshaw cells (postsynaptic inhibition)
- Produces a generalized convulsion
- Added to heroin and causes overdose
- Rat poison
Define the action of picrotoxin
- Blocks GABA receptors
- Blocks GABA-induced increased chloride conductance and decreasing cAMP concentrations
- Produces conic convulsions by blocking presynaptic inhibition
Define action of pentylenetetrazole (Metrazole)
Decreases neuronal recovery time by increasing K permeability
- **Used for provocative diagnosis of epilepsy
- General cortical convulsant
Keeps people awake
Indication for Stimulants
Used as an antidote for depression = analeptics
- No one drug that is very effective
- ***Primarily used to reverse respiratory, cardiac and CNS depression
What is an analeptic
a drug that acts as a restorative
Primary classes of stimulants
- Xanthenes
- Centrally acting sympathomimetics
- Convulsants
General use for Xanthenes
Primarily used for asthma to reverse respiratory depression (Bronchodilators)
General use for centrally acting sympathomimetics
Used primarily for hyperkinetic children
- Amphetamine is prototype
2 drugs for asthma, chronic bronchitis, COPD (Xanthene)
aminophylline
theophylline
How much caffeine or theophylline is needed to increase cortical activity? How much is in an OTC stimulant?
50-200 mg (1 to 4 cups of coffee)
-*** OTC stimulants have 100-200 mg
CNS and respiratory stimulation in order of potency
- Cerebral Cortex = 50-200 mg (Small dose produces effect = more potent)
- Brain Stem = >250 mg (greater dose required)
- Spinal cord = 1000 mg (highest dose required –> **Can lead to convulsions, shakiness
Summary of Pharmacological Effects by potency/Efficacy
CNS --> caffeine = theophylline BV --> theophylline > caffeine Heart --> theophylline > caffeine SM musc --> theophylline > caffeine SK musc --> caffeine > theophyline Diuresis --> theophylline > caffeine
Describe the Blood vessel dilation effects of Xanthenes
- Blood vessel dilation (dilation in coronary and peripheral blood vessels) **BETA 2 Effect
- caffeine decreases peripheral resistance
- Can make someone hypotensive
- **theophylline more potent than caffeine
- Blood vessel Constriction (cerebral blood vessels)
- Treatment for headache
Describe the Cardiac Muscle stimulation effects of Xanthenes
Beta 1 effect
- **Increases cardiac output
- theophylline more stimulatory than caffeine
- theophylline = inhibits ADH which increases perfusion
- caffeine = hypotension (smooth muscle relaxation of vasculature in periphery), normal heart rate
- ** caffeine will cause arrhythmias in someone who is at risk for arrhythmias but does not produce arrhythmias in a normal heart