Summary Pharmacology CNS Drugs Latest Edition 2024

  Tolerance - state where one must increase the dose of a drug in order to achieve or maintain the desired effect (all narcotics, barbiturates, alcohol, tobacco) 2 types of tolerance: metabolic receptor - Metabolic: enzymes system working differently; breaking the drug down faster; eliminating the drug faster so increase in dose to keep the therapeutic level Receptor: up regulation or down regulation of receptors and therefore altering the need for different drugs Drug abuse - difficult to define; conveys notion of chronic use and social disapproval; using a drug that is inconsistent with medical or social norms Physical dependence - an adaptive physiological state that occurs after administration of a drug that manifest itself by physical disturbances when the drug is withdrawn (withdrawal syndrome) Psychological dependence - a state of emotional reliance upon a drugs in order to maintain a state of well-being. Tolerance, if it does occur, is of the "metabolic" type so there are no withdrawal symptoms Withdrawal syndrome - a group of sign and symptoms that occur in physical dependent individuals when they discontinue drug use. usually the effect of the withdrawal is the opposite of the known effect of the drug. In reality, dependence causing drug usually are? - Both physical dependence and psychological dependence at the same time. they are on a continuum between the two extremes w/ some features of both Because addiction deals with "compulsion" to "self-administer" a drug, many agents that have strong psychological "hooks" are very addicting even though their degree of physical dependence is not that high - Degree of physical dependence is NOT equivalent with degree of addiction How does the CNS stimulants work? - substances increase the excitability of the CNS What are the 3 types of stimulants discussed in class? - 1. amphetamines 2. Xanthines 3. Cocaine Amphetamines stimulant: Responses observed upon administration: - 1. increased alertness, wakefulness, decreased fatigue 2. euphoria 3. decreased appetite, but not psychological eating Amphetamines stimulant: Mechanism of action: - increase norepi and dopamine Amphetamines stimulant: Therapeutic uses - 1. narcolepsy 2. weight control 3. attention deficit-hyperactivity disorder ADHD Amphetamines stimulant: what medication is used most often to treat ADHD? MOA? - Methylphenidate (Ritalin) is used most often MOA: increase norepi and dopamine Amphetamines stimulant: Side or toxic effect in ADHD kids - 1. sleeplessness, excessive crying, etc. 2. suppression of growth that can be reversed if quit before bone closure Amphetamines stimulant: Side or toxic effects - 1. CNS - nervousness, anxiety, sleeplessness 2. Cardiovascular - increased h.r., b.p., and possibly arrhythmias 3. weight loss and malnutrition 4. bone marrow suppression Amphetamines stimulant: Contraindications/Cautions - Contraindications: 1. Insomnia or psychological disorders 2. Hypertension, cardiac arrhythmia 3. Anorexia Cautions: potential for abuse Drug interactions: anticholinergics, anticoagulant, anticonvulsants, tricyclic antidepressants - usually requires a dosage adjustment 3 types of xanthine stimulant - - caffeine - coffee beans, tea leaves, kola nuts - theophylline - tea leaves - theobromine - cocoa Xanthines stimulant: Responses observed upon administration: - 1. CNS stimulation - increase alertness, decreased fatigue 2. Cardiac stimulant (rate and force of contraction) 3. Constricts blood vessels 4. Diuresis - decrease fluid 5. Bronchiorelaxation Xanthines stimulant: Mechanism of Action - 1. inhibits the break down of cyclic AMP 2. increases CNS activity 3. dilate bronchioles 4. dilate pulmonary blood vessels, but constrict cerebral vessels NOTE: IT ACTIVATES P450 ENZYME WHICH AFFECTS THE METABOLISM OF MANY OTHER DRUGS Xanthines stimulant: Therapeutic use - 1. pain from headaches 2. asthma, bronchitis, emphysema 3. counter drowsiness Xanthines stimulant: Side or toxic effect - 1. increase heart rate, cardiac arrhythmia (PVC) 2. increase gastric secretion 3. diuresis 4. excessive CNS stimulation - convulsions, insomnia 5. withdrawal - headache and irritability Xanthines stimulant: Caution - 1. cardiac arrhythmia 2. ulcers 3. possibly pregnancy Cocaine stimulant: Similar to amphetamine in: - 1. responses observed 2. mechanism of action on CNS 3. many side/toxic effect 4. contraindications/cautions Cocaine stimulant: Mechanism of action - Block nor-epi, serotonin, dopamine re-uptake into presynaptic terminals Cocaine stimulant: Different from amphetamines: - Cocaine is NOT approved by the FDA EXCEPT as local anesthetic - only used in the hospital or clinic Cocaine stimulant: