Other Drugs of Abuse: Nicotine and Psychostimulants Flashcards
Stimulants (AKA psychomotor stimulants) ______ activity of the CNS, causing the following symptoms: (4)
increase
- Excitement
- Euphoria
- Increased motor activity
- Decrease feelings of fatigue
Therapeutic indications for some stimulants (4)
- ADHD
- Narcolepsy
- Anorexiant (obesity)
- Obstruction/sleep apnea (respiratory stimulant)
Nicotine is the active component in ______. It is a ______ and ______ ______ stimulant.
Tobacco; CNS; autonomic ganglia
At concentrations achieved during recreational tobacco use, nicotine has ______ affinity for ______.
higher; NnAChR (Neuronal nicotinic acetylcholinergic receptors)
Nicotine exerts a combination of ______ and ______ effects. Nicotine can ______, then ______ neuronal nicotinic receptors.
Stimulatory; inhibitory; stimulate; desensitize
At low doses in the CNS, nicotine stimulates: (4)
- Euphoria
- Arousal
- Relaxation
- Improves attention, learning, and problem solving
At high doses in the CNS, nicotine stimulates: (4)
- Tremors
- Convulsions
- Arrhythmias
- Respiratory paralysis
Nicotine has a biphasic effect of transient stimulation and depression that occurs with all autonomic ganglia (esp. at high doses). Small doses ______ ganglion cells; large doses ______ ganglionic transmission.
Stimulate; block
In the adrenal medulla, small doses of nicotine ______ the discharge of ______. Large doses ______ ______ due to splanchnic nerve ______.
Discharge; catecholamines; prevent release; stimulation
In the neuromuscular junction, ______ phase by nicotine is rapidly obscured by paralysis (toxic doses)
Stimulation
Nicotine also has affinity for: (4)
- Mechanoreceptors in the skin, mesentery, tongue, lung, and stomach
- Chemoreceptors in the carotid body
- Thermal receptors of the skin and tongue
- Pain receptors
Physiological effects of nicotine (3)
- Respiratory depression - central paralysis and paralysis of diaphragm/intercostal muscles
- Largely sympathomimetic: vasoconstriction, tachycardia, hypertension
- Parasympathomimetic in the GI tract and urinary system: nausea/vomiting (stimulation of chemoreceptors in the area postrema, vagal and spinal afferents), increased tone and motor activity of the bowel, and increased urinary voiding
Acute nicotine toxicity (6)
- Fatal dose of 40 mg (amount in 2 cigarettes); toxicity is limited by emetic effects, so less absorption occurs if high doses are ingested
- If patient is experiencing CNS-stimulant actions (convulsions, coma, respiratory arrest) - treat with diazepam
- If patient is experiencing skeletal muscle end-plate depolarization blockade (respiratory paralysis of diaphragm and intercostal muscles) - treat with mechanical ventilation
- If patient is experiencing HTN and cardiac arrhythmias - treat with Atropine to control muscarinic excess
- Patients who survive the first 4 hours usually recover completely, assuming hypoxia and brain damage have not occurred
- Nicotine is rapidly metabolized and excreted
Pharmacokinetics and metabolism of nicotine (6)
- Metabolized by CYP2D6 and glucuronidation
- Nicotine INDUCES expression of CYP1A2 (caffeine) and CYP2E1 (alcohol)
- Eliminated by renal excretion of parent drug and metabolites
- Absorbed through multiple routes: skin, mucous membranes, lungs
- Administration via smoking (lungs) yields CNS affects in 7 seconds
- Positive reinforcement closely associated with the behavior
Nicotine withdrawal (4)
- Symptoms: irritability, impatience, hostility, anxiety, dysphoric/depressed mood, difficulty concentrating, restlessness, increased heart rate, increased appetite or weight gain
- Urge to smoke correlates with low levels of nicotine in blood
- First-line medications reliably increase long-term smoking abstinence: nicotine replacement therapy (gum, inhaler, lozenge, nasal spray, transdermal patch), bupropion, varenicline (Chantix)
- Rimonabant - inverse agonist of CB1 receptor - improved smoking abstinence rates and reduced weight gain, but increased risk of suicidality