Psychostimulants Overview Quiz

Psychostimulants: Cocaine, Amphetamines

• Psychostimulants include cocaine and amphetamines.
• Learning outcomes include familiarization with common examples, understanding mechanisms of action, and describing side effects associated with abuse.
• CNS stimulants include cocaine, crack cocaine, amphetamines, methamphetamine, methylphenidate, and others.

CNS Stimulants

• Cocaine comes in powder and crack forms.
• Amphetamines include different types like D-amphetamine, methamphetamine, methylphenidate (Preludin), and others.
• Hallucinogens include MDA, MDMA, and DOM.
• Khat includes cathinone and methcathinone.
• Methylxanthines, like caffeine and theophylline, were used to treat asthma.

Cocaine Overview

• Cocaine is an alkaloid from the Erythroxylon coca plant.
• It's native to Western South America.
• Coca leaves are used for religious, mystical, social, and medicinal purposes.
• Main stimulant uses include endurance, feelings of well-being (euphoria), and hunger suppression. These are used by athletes and for weight loss.
• Cocaine also has medical uses as a local anesthetic and vasoconstrictor for nasal congestion.

Cocaine Production

• Cocaine paste is extracted from soaked and mashed coca leaves (60-80% cocaine content).
• Cocaine powder is made by mixing the paste with hydrochloric acid.
• Freebase/crack cocaine is extracted from the powder using baking soda.

Amphetamine Overview

• Amphetamines are synthetic analogs of ephedrine.
• They're commonly found in mahuang, a plant used in China for asthma treatment.
• Methamphetamine and methylphenidate (Ritalin) are similar in structure.
• Medical uses include treating obesity, ADHD, and narcolepsy.

Chemical Structure of Stimulants

• Chemical structures of cocaine, amphetamines, methamphetamine, and methylphenidate are provided in image format.

Neurophysiology

• Cocaine blocks the reuptake of norepinephrine, keeping it at the synaptic membrane.

Cocaine Pharmacology by Route of Administration

• Inhalation ("crack" cocaine) has a very fast onset of action (8 seconds).
• Intranasal administration of cocaine powder also has a relatively fast onset (2-5 minutes).
• Intravenous administration has an even faster onset (seconds).
• Oral administration generally has a slower onset (30-60 minutes).

Effects on Mind, Brain, Behavior

• Stimulants increase alertness, concentration, mental acuity, sensory awareness, euphoria, and brain electrical activity.
• They can also increase self-confidence and grandiosity, and increase the need for sleep thereby causing insomnia.
• Stimulants can decrease appetite, brain blood flow, and glucose metabolism.
• Stimulants can increase anxiety, suspiciousness (paranoia), convulsions, tremors, seizures, and psychosis (delirium).
• They can increase restlessness—the inability to stay at one place.

Peripheral Effects

• Stimulants increase blood pressure, blood sugar, heart rate (including irregular heartbeats), vasoconstriction, body temperature, and bronchodilation.
• These can cause impaired breathing.
• Causes of death can involve the heart because stimulants affect the AV node causing ventricular tachycardia.

Clinical Effects of Sympathomimetics

• Sympathomimetics can cause hypertension and hyperthermia.
• Tachycardia, dilated pupils (mydriasis), sweating (diaphoresis), and central nervous system excitation are also commonly observed.

Cocaine Cardiac Features

• Cocaine can cause dysrhythmias due to sodium and potassium blockade.
• Supraventricular tachycardia (SVT), wide or prolonged QRS is a serious concern.
• Atrial fibrillation/flutter and wide complex tachycardia can occur.

Body Packer/Stuffer

• Body packers and stuffers are individuals who smuggle drugs by swallowing or concealing substances to avoid detection.

Cocaine Pharmacokinetics: Absorption

• Routes of administration include insufflation (snorting), intravenous (IV) injection, inhalation (freebasing), and oral ingestion.

Pharmacokinetics: Distribution and Metabolism

• Cocaine and amphetamines readily penetrate the blood-brain barrier (BBB).
• Cocaine has a half-life of 50-90 minutes.
• Amphetamines have a half-life of 5-10 hours.
• Methamphetamine has a half-life of about 12 hours.
• Metabolites can be active or inactive compounds and sometimes cocaine autometabolizes in the blood.
• Cocaine metabolites include norcocaine, ecgonine methyl ester, and benzoylecgonine.

Cocaethylene

• Alcohol inhibits the metabolism of cocaine causing it to accumulate and last longer in the body.
• Alcohol and cocaine chemically react to form cocaethylene.
• Cocaethylene has a similar effect to cocaine but with greater cardiac toxicity compared to cocaine.

Cocaine Pharmacodynamics

• Cocaine is an indirect agonist for dopamine (high affinity), norepinephrine (high affinity), and serotonin (modest affinity).
• Its mechanism of action involves blocking monoamine reuptake.

Amphetamine Pharmacodynamics

• Amphetamines are also indirect agonists, with high affinity for dopamine and norepinephrine.
• They also have low affinity for serotonin
• Mechanisms of action include blocking monoamine reuptake, inhibiting vesicular storage, inhibiting MAO metabolism, and reversing reuptake.

Tolerance, Withdrawal, Addiction

• Withdrawal symptoms can include physical symptoms such as hunger, fatigue, anxiety, irritability, and depression, along with dysphoric symptoms like decreased activity, amotivation, intense boredom, and intense craving.
• The severity and duration of withdrawal symptoms can vary, from mild and moderate to severe and prolonged, potentially lasting for weeks.
• The route of administration plays a significant role in the risk of addiction.

Khat

• Khat ingestion, in large amounts can cause sympathomimetic effects like seizures, and cardiac arrhythmias.
• Addiction is typically physiological.

Causes of Stimulant-Induced Chest Pain

• Noncardiac causes of chest pain include pneumothorax, pneumomediastinum, pneumopericardium, aortic dissection, pulmonary infarction, infection, foreign body aspiration, endocarditis, and pericarditis.
• Ischemic or infarct events, often due to vasoconstriction can also cause chest pain.
• Acute intoxication and coronary stent thrombosis are other possible causes.

Sympathomimetic Treatment

• Benzodiazepines are a first-line treatment for toxicity.
• β-blockers are contraindicated in cases of unopposed alpha-receptor stimulation, requiring alpha-blockade with phentolamine to block alpha-receptors.
• Sodium bicarbonate and benzodiazepines are used in cases of sodium wide complex tachycardia as a treatment.
• Decontamination methods like bowel irrigation might be necessary.
• Activated charcoal is used for preventing further toxicity from pills.

This quiz covers the key aspects of psychostimulants, including cocaine and amphetamines. You will learn about their mechanisms of action, side effects, and various forms. The quiz aims to enhance your understanding of these substances and their effects on the central nervous system.