💊أدويه الجهاز العصبي 19
#Pharmacology_of_CNS 19
#CNS
#CNS_Stimulants
مواضيع البوست 👇
✔️PSYCHOMOTOR STIMULANTS
✔️HALLUCINOGENS
💠Psychomotor stimulants and hallucinogens are two groups of drugs that act primarily to stimulate the central nervous system (CNS)
💠The psychomotor stimulants cause excitement and euphoria, decrease feelings of fatigue, and increase motor activity.
💠The hallucinogens produce profound changes in thought patterns and mood, with little effect on the brainstem and spinal cord.
✔️PSYCHOMOTOR STIMULANTS
✅Methylxanthines
🔘The methylxanthines include theophylline, which is found in tea; theobromine, found in cocoa; and caffeine
🔷Mechanism of action:
🌀Several mechanisms have been proposed for the actions of methylxanthines, including translocation of extracellular calcium, increase in cyclic adenosine monophosphate and cyclic guanosine monophosphate caused by inhibition of phosphodiesterase, and blockade of adenosine receptors.
🔷Actions:
🌀CNS:causes a decrease in fatigue and increased mental alertness
🌀Cardiovascular system:has positive inotropic and chronotropic effects on the heart.
🌀Diuretic action: Caffeine has a mild diuretic action that increases urinary output of sodium, chloride, and potassium.
🌀Gastric mucosa:stimulate secretion of gastric acid
🔷Therapeutic uses:
🌀Caffeine and its derivatives relax the smooth muscles of the bronchioles.Caffeine is also used in combination with the analgesics acetaminophen and aspirin for the management of headaches in both prescription and over-the-counter products.
🔷Pharmacokinetics
🌀The methylxanthines are well absorbed orally.
🌀These drugs cross the placenta to the fetus and are secreted into the breast milk.
🔷Adverse effects:
🌀Moderate doses of caffeine cause insomnia,anxiety, and agitation. A high dosage is required for toxicity, which is manifested by emesis and convulsions.
🌀Lethargy,irritability, and headache occur in users who routinely consume more than 600 mg of caffeine per day (roughly six cups of coffee per day) and then suddenly stop.
✅Nicotine
🔘Nicotine is the active ingredient in tobacco.
🔘 In combination with the tars and carbon monoxide found in cigarette smoke, nicotine represents a serious risk factor for lung and cardiovascular disease, various cancers, and other illnesses.
🔷Mechanism of action:
🌀In low doses, nicotine causes ganglionic stimulation by depolarization. At high doses, nicotine causes ganglionic blockade.
🔷Actions:
🌀Nicotine is highly lipid soluble and readily crosses the blood–brain barrier. Cigarette smoking or administration of low doses of nicotine produces some degree of euphoria and arousal, as well as relaxation. It improves attention, learning, problem solving, and reaction time.
🌀The peripheral effects of nicotine are complex. Stimulation of sympathetic ganglia as well as of the adrenal medulla increases blood pressure and heart rate. Thus,use of tobacco is particularly harmful in hypertensive patients.
🌀nicotine induced vasoconstriction can decrease coronary blood flow,
adversely affecting a patient with angina
🌀At higher doses, blood pressure falls and activity ceases in both the gastrointestinal (GI) tract and bladder musculature as a result of a nicotine-induced block of parasympathetic ganglia
🔷Pharmacokinetics:
🌀Because nicotine is highly lipid soluble, absorption readily occurs via the oral mucosa, lungs, GI mucosa, and skin.
🌀By inhaling tobacco smoke,the average smoker takes in 1 to 2 mg of nicotine per cigarette.
🌀More than 90% of the nicotine inhaled in smoke is absorbed.
🌀Tolerance to the toxic effects of nicotine develops rapidly, often within days.
🔷Adverse effects:
🌀The CNS effects of nicotine include irritability and tremors. Nicotine may also cause intestinal cramps, diarrhea,and increased heart rate and blood pressure.
🔷Withdrawal syndrome:
🌀Withdrawal is characterized by irritability, anxiety, restlessness, difficulty concentrating,headaches, and insomnia
أدويهCns20
#Pharmacology_of_CNS 20
#CNS
تابع للموضوع السابق
🌀The transdermal patch and chewing gum containing nicotine have been shown to reduce nicotine withdrawal symptoms and to help smokers stop smoking
✅Varenicline
🔘Varenicline is a partial agonist at neuronal nicotinic acetylcholine receptors in the CNS. Because varenicline is only a partial agonist at these receptors, it produces less euphoric effects than nicotine
🔘varenicline tends to attenuate the rewarding effects of nicotine if a person relapses and uses tobacco.
✅Cocaine
🔘Cocaine is a widely available and highly addictive drug.
🔘The primary mechanism of action underlying the effects of cocaine is blockade of reuptake of the monoamines (norepinephrine, serotonin, and dopamine) into the presynaptic terminals
✅Amphetamine
🔘Amphetamine is a sympathetic amine that shows neurologic and clinical effects quite similar to those of cocaine.
🔘Methamphetamine (also known as “speed”) is a derivative of amphetamine available for prescription use.
🔘3,4-Methylenedioxymethamphetamine (also known as MDMA, or Ecstasy) is a synthetic derivative of methamphetamine with both stimulant and hallucinogenic properties
🔷Mechanism of action:
🌀As with cocaine, the effects of amphetamine on the CNS and peripheral nervous system are indirect. That is, both depend upon an elevation of the level of catecholamine neurotransmitters in synaptic spaces
🔷Actions:
🌀The major behavioral effects of amphetamine result from a combination of its dopamine and norepinephrine release enhancing properties.leads to increased alertness, decreased fatigue, depressed appetite,and insomnia.
🌀In addition to its marked action on the CNS, amphetamine acts on the adrenergic system, indirectly stimulating the receptors through norepinephrine release.
🔷Therapeutic uses:
🌀Attention deficit hyperactivity disorder (ADHD):
▪️Some young children are hyperkinetic and lack the ability to be involved in any one activity for longer than a few minutes.
Dextroamphetamine,methamphetamine, the mixed amphetamine salts, and methylphenidate can help improve attention span and alleviate many of the behavioral problems associated with this syndrome, in addition to reducing hyperkinesia
🌀Narcolepsy:
▪️Narcolepsy is a relatively rare sleep disorder that is characterized by uncontrollable bouts of sleepiness during the day. It is sometimes accompanied by catalepsy, a loss in muscle control, and even paralysis brought on by strong emotions such as laughter.
▪️The sleepiness can be treated with drugs, such as the mixed amphetamine salts or methylphenidate. Modafinil and its R-enantiomer derivative,
armodafinil, are considered first-line agents for the treatment of narcolepsy
🌀Appetite suppression:
▪️ Phentermine and diethylpropion are sympathomimetic amines that are related structurally to amphetamine. These agents are used for their appetite-suppressant effects in the management of obesity
🔷Pharmacokinetics:
🌀Amphetamine is completely absorbed from the GI tract, metabolized by the liver, and excreted in the urine.
🌀The euphoria caused by amphetamine lasts 4 to 6 hours, or four- to eightfold longer than the effects of cocaine.
🔷Adverse effects:
🌀CNS effects:Adverse effects of amphetamine usage include insomnia, irritability, weakness, dizziness, tremor, and hyperactive reflexes, confusion, delirium, panic states, and suicidal tendencies,
especially in mentally ill patients.
🌀Cardiovascular effects: palpitations, cardiac arrhythmias, hypertension,anginal pain, and circulatory collapse. Headache, chills, and excessive sweating may also occur.
🌀GI system effects:anorexia, nausea, vomiting, abdominal cramps, and diarrhea.
🔷Contraindications:
🌀Patients with hypertension, cardiovascular disease, hyperthyroidism, glaucoma, or a history of drug abuse or those taking MAO inhibitors should not be treated with amphetamine.
✅Methylphenidate
🔘Methylphenidate has CNS-stimulant properties similar to those of amphetamine and may also lead to abuse, although its addictive potential is controversial.
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