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CNS Stimulants 2


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What are the indirectly acting sympathiomimetic amine drugs?
Alternative drug to amphetamines to treat narcolepsy?
Modafinil (provigil)
Amphetamines are considered what schedule drug?
II: high abuse potential and high propensity to cause psychological dependence
What is the amphetamine structure like?
A catecholamine x more lipid soluble--rapidly penetrates the BBB
What does NH4Cl- have to do with amphetamines?
It acidifies the urine and increases its rate of elimination. Used in detox.
What is the mechanism of action for amphetamines?
1. Pentrates the neuron terminal by diffusion and riding the amine transporters
2. It displaces amines in the vesicles (NE, DA, 5-HT); b/c it is a weak-base and disrupts pH.
3. The displaced amines leave the terminal via reverse uptake by the transporters.

OVERALL: Massive release of NE and DA (>5-HT) into the synaptic cleft
What is the ph of amphetamines?
pKa: 9.9= weak base b/c an amine
What are the respective effects of massive release of DA and NE?
DA= "high" and addictive properties (reward pathway)
NE=sleep-supressing effect
What are the SE of amphetamines in the periphery?
a and B Adrenergic Receptors (NE): increase atrial pressure and tachycardia
What are the CNS SE of amphetamines?
*inc. alertness
*delayed sleep
*dec. fatigue
*inc. motor and speech activity
What is the rebound phenomemon with amphetamines?
After the Major CNS effects: period of depression, hypersomnia, depression
What are the effects of amphetamines at high doses?
*psychotic state-sim. to paranoid schizo.
*can trigger convulsions
*severe HTN and stroke
How do you treat amphetamine OD/toxicity?
*nitroprusside or a-blocker if BP severely elevated
*Sedative drugs
What are the therapeutic uses of Amphetamines?
What are the drugs used to treat narcolepsy?
Amphetamines= D-amphetamine or methylphenidate (i.e. ritalin)
Modafinil=not amphet. tx's narc
What drugs are used to treat cataplexy component of narcolepsy?
clomipramine(TCA) or fluoxetine (SSRI) (anti-depressants)
What are the drugs used to treat obesity?
Orlistat (pancreatic lipase inhibitor)
Sibutramine (meridia)-inhibit NE and serotonin re-uptake
What is Sibutramine?
It is a selective NE and serotonin re-uptake inhibitor that does not affect DA. Used as an anorectic drug for severe obesity.
What is methylphenidate?
Piperidine derivative of amphetamine.
What are alternative tx for ADHD?
TCA-deipramine, clonidine, atomoxetine(related to clonidine)
What is the mechanism of action of cocaine?
Blocks uptake of DA, NE and 5-HT. Increase synaptic levels of the amines.
What is crack?
is cocaine base. Very lipid soluble and smokable
What are the clinical uses of cocaine?
A local anesthetic-nasal and oral made in a form that will not enter the CNS
What is the action of DA receptor antagonists in a cocaine patient?
I.e: Neuroleptics
*alleviate the cocaine-induced psychosis, and the convulsions but do not change Peripheral toxic sx
What drug is used to stop cocaine convulsions?
Diazepam IV (benzo)
What are methylxanthines?
Alkaloids found in tea, coffee, cocoa and other plants.
What are the 3 main effects of theophylline and caffeine in the CNS?
1. increased alertness
2. respiratory stimulation
3. convulsive potential at high dose
What is the mechanism of action for methylxanthines?
1. Low dose: (teas) competitive inhibition of CNS adenosine A1 and A2 receptors.
2. High does: (theophylline-asthma) inhibit PDE and inc. cAMP.
What is the function of adenosine in the brain?
Depresses neuronal function by activating A1R coupled to K-channels. Post and Pre-syn. Presyn= inhibition of NT release
Where are the A2 receptors located?
A2R-high conc. in the striatum-role in motor function.
What are the medical uses of methyxanthines?
1. Primary apnea of prematurity (caffeine or theophylline)- b/c of weak hypoxia chemoreflexes that can't overcome adenosine in brainstem.
2. Asthma tx- high doses the bronchodilatory effect
How would you describe the nicotine compound?
*lipid-soluble drug well absorbed by the skin and mucosa.
*Activates nicotinic R
What is the mechanism of Nicotine at low doses?
Activate N-R in autonomic ganglia, lungs/airways and CNS--largely a presynaptic receptor--inc. release of DA by depolarization of the terminals
What are the effects of Nicotine at high doses?
N acts on all nicotinic receptors and produces a depolarizing blockade and receptor desenesitization at autonomic ganglia and NMJ. EFFECT: peripheral CVS collapse, muscle weakness, resp. failure->death
what are the SE of Nicotine at low doses?
*Nausea-stim lung,airway affer. and area posterma
*inc. respiration (carotid chemo)
*tremor, inc. alertness, fac. memory and attention, muscle relax (?via renshaw cell activation of SC)
*activ auto ganglia (both) and adrenal medulla--GI and CVS
What is the half-life of nicotine?
2hrs, heavy smokers titrate blood in narrow lmits
Clinical uses of nicotine?
Treatment of addiction by replacement therapy.
What are the major groups of Stimulants?
1. Indirect acting sympathiomemetic amines: amphetamines, methyphenidate, cocaine
2. Methylxanthines
3. Nicotine

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