The Central Nervous System Pharmacology I BMS 242 The Central Nervous System CNS Stimulants L. Aya M. Serry 2017

Lecture Objectives Introduction and Classification of CNS Stimulants Psychomotor Stimulants; Body Effects Therapeutic Uses Side Effects Psychotomimetic Stimulants;

What are CNS Stimulants? CNS Stimulants are drugs that induce temporary improvements in either mental or physical functions or both Examples of these kinds of effects may include enhanced alertness and wakefulness

CNS Stimulants General Body Effects Elevate Mood Increase Motor Activity Increase Alertness Decrease need for Sleep In case of overdose lead to convulsion and death

CNS Stimulants 

A) Psychomotor Stimulants

1- Methylxanthines Caffeine Theophylline Theobromine They are all from plant origin, Caffeine is the most widely consumed stimulant in the world which is present in high concentrations in coffee beans , also in tea and cocoa

Effects on different organs 1- Methylxanthines (Caffeine) Effects on different organs Caffeine Normal Dose is 400 mg/day which is equivalent to 4 cups of coffee, 10 cans of coke and 2 energy boosting drinks

Methylxanthines (Caffeine) Withdrawal symptoms start with people consuming <600 mg/day It has a synergistic effect with NSAIDs and increases their absorption

2- Nicotine CNS stimulant found in Tobacco plant No Therapeutic value (Except Nicorette®) Cigarette smoke has a serious risk factors for respiratory, CVS diseases and Cancers (Cigarette: Not only nicotine, Tar and Carbon Monoxide) It causes dependence and withdrawal symptoms are not easily overcome

2- Nicotine Effects on the body: Low doses: Arousal, relaxation, Increased attention and decreased appetite High doses: Central respiratory depression and severe hypotension ( only with nicotine-containing pesticides) Nicotine stimulates Nicotinic receptors (Nn), as a result increased both Sympathetic and Parasympathetic body effects

2- Nicotine Smoking cessation program (Drug and Behavioral treatments): Varenicline (Champix®) Very effective drug that is a partial agonist on Nn receptors A treatment program of 12 weeks Side effects : Nausea, Vomiting and sleep disturbances Day 1-3; 0.5 mg once daily Day 4-7 0.5 mg twice / day Day 8- 12 weeks , 1 mg twice/day

3- Cocaine Strong CNS stimulant from Coca plant Used topically as local anaesthetic Mechanism Of Action: Serotonin, NE, Dopamine reuptake inhibitor [ SNDRI] Administration: smoking-snorting or I.V.

3- Cocaine Effects on the body: Feeling of well-being and euphoria Increases mental alertness and attention Side effects: Increased heart rate, Mydriasis, increased body temperature Overdose: tachycardia, convulsions and respiratory failure Highly addictive, withdrawal symptoms appear soon after discontinuation

4- Amphetamines

Amphetamines

4- Amphetamines These drugs are highly addictive Body Effects: Wakefulness- euphoria – increase alertness and suppress appetite They are administered illegally (I.V. and smoking) and abused as performance and cognitive enhancers (e.g: athletes)

4- Amphetamines

4- Amphetamines Methamphetamine (Street name: Speed) and Fenethylline (Captagon®) Most addictive and highly abused amphetamines Methylphenidate [ Ritalin®] The least addictive so it is used in ADHD treatment Modafinil Wakefulness-promoting agent Used in Narcolepsy treatment Used by aviators in military services to increase wakefulness

B) Psychotomimetic Stimulants

Dronabinol The pharmacological actions of Dronabinol (THC) result from its partial agonist activity at the cannabinoid receptor CB1, Located mainly in the central nervous system, and the CB2 receptor, mainly expressed in cells of the immune system The psychoactive effects of THC are primarily mediated by its activation of CB1 G-protein coupled receptors

Dronabinol

Dronabinol

CNS Stimulants Uses Indications Analeptics (CNS stimulants) Reversal of anaesthesia-induced respiratory depression Anorexiants Thought to suppress the appetite control centre in the brain (Withdrawn lately from Markets) ADHD Stimulate the areas in the brain responsible for mental alertness and attentiveness Narcolepsy Increase mental alertness Migraine headaches *Caffeine, co-administered with other drugs, used to treat headaches