Pharmacology in Nursinggggggggggggggggggggggggggggggggggg

Ffffffffffffffffffffffffffffffff

1. Drugs Affecting the Central Nervous System

2. Review of the Anatomy and Functions of the Nervous System The nervous system has two major components: the central nervous system (CNS) and the peripheral nervous system. The central nervous system (CNS) is composed of the brain and the spinal cord. The peripheral nervous system includes nerves outside the brain and spinal cord and consists of sensory neurons and motor neurons. Sensory neurons sense the environment and conduct signals to the brain that become a conscious perception of that stimulus. This conscious perception may lead to a motor response that is conducted from the brain to the peripheral nervous system via motor neurons to cause a movement. Motor neurons consist of the somatic nervous system that stimulates voluntary movement of muscles and the autonomic nervous system that controls involuntary responses.

3. How Do Drugs Affect The Central Nervous System? Drugs are substances that alter or influence the human body and brain. They are often prescribed to treat medical conditions such as pain, anxiety, depression, insomnia, and other health problems, and illicit drugs are used illegally for recreational purposes – which can often lead to addiction.

4. Effects of Drugs on The Brain & Neurotransmitters Mind-altering drugs may slow down or speed up the central nervous system and autonomic functions necessary for living, such as blood pressure, respiration, heart rate, and body temperature. Levels of some of the brain’s chemical messengers, or neurotransmitters, are also impacted by drug abuse, including: Dopamine:  This neurotransmitter regulates moods, enhances pleasure, and is involved with movement, reward and reinforcing behaviors, motivation, and attention. Serotonin:  This neurotransmitter is responsible for stabilizing moods and regulating emotions. Gamma-aminobutyric acid (GABA):  GABA acts as a natural tranquilizer, mitigating the stress response and lowering anxiety levels as well as slowing down functions of the central nervous system. Norepinephrine:  Similar to adrenaline, norepinephrine is often called the “stress hormone,” as it speeds up the central nervous system in response to the “fight-or-flight” response. It also homes focus and attention while increasing energy levels.

5. Which Drugs Affect The CNS?

6. Types Of Drugs And Their Effects On The Nervous System There are two main categories of drugs that describe the effects that they have on the brain:  stimulants  and  depressants . A depressant drug is less about causing depression, as both stimulants and depressants can cause poor mental health, and more about lowering or depressing brain function. Stimulants have the opposite effect. This has less to do with making you feel happy and more to do with speeding up or stimulating your nervous system.

7. Stimulant Drugs Stimulants are drugs that exert their action through excitation of the central nervous system. Psychic stimulants include caffeine, cocaine, and various amphetamines. These drugs are used to enhance mental alertness and reduce drowsiness and fatigue.

8. Caffeine, a natural stimulant found in various beverages and some medications, exerts its effects on the central nervous system (CNS) by interacting with adenosine receptors. Adenosine is a neurotransmitter that plays a role in promoting relaxation and sleepiness. Caffeine's molecular structure is similar to that of adenosine, allowing it to bind to adenosine receptors without activating them, effectively blocking their effects.

9. Cocaine and other stimulants activate brain receptors that increase the speed and intensity of brain signals. While multiple central nervous system receptors may be affected, dopamine receptors are the  main type  impacted. Using stimulants causes hyperactivity along with a feeling of invigoration and ability. It also strongly impacts the body’s normal processes, increasing heart rate, blood pressure, respiratory rate and other physiological processes. This can cause strain on the body which could be dangerous.  People who use stimulants will typically have a period of hyperactivity where they feel very focused and powerful. They often push themselves beyond what they would normally be capable of without getting tired. A crash follows this period as the effects of the drug wear off, and the period of hyperactivity causes extreme tiredness and fatigue.  

10. Amphetamines The stimulation caused by amphetamines is caused by excessive release of norepinephrine from storage sites in the peripheral nervous system. It is not known whether the same action occurs in the central nervous system. Two other theories for their action are that they are degraded slower than norepinephrine or that they could act on serotonin receptor sites. Therapeutic doses of amphetamine elevate mood, reduce feelings of fatigue and hunger, facilitate powers of concentration, and increase the desire and capacity to carry out work. They induce exhilarating feelings of power, strength, energy, self-assertion, focus and enhanced motivation. The need to sleep or eat is diminished.

11. Depressant Drugs These drugs decrease the activity of the brain. Depressants slow down the firing of neurons and reduce the release of neurotransmitters. Examples include alcohol, barbiturates, benzodiazepines, chloral hydrate, dextromethorphan, heroin, ketamine, lorazepam, meprobamate, morphine, phenobarbital, pentobarbital, propofol, thiopental sodium, tricyclic antidepressants, and zopiclone.

12. Alcohol and benzodiazepines work by  stimulating  GABA receptors. When activated, these receptors suppress other brain signals. Using these substances results in suppressed brain signals, causing relaxation while slowing many of the body’s normal processes. This effect causes many of the symptoms associated with the use of alcohol and other similar depressants. Symptoms like slurred speech, decreased coordination, forgetfulness or even low heart rate and breathing occur because the hyperactive GABA receptors suppress brain signals in the central nervous system.

13. Psychotropic Drugs Psychotropic  drugs affect  the mind by altering brain chemistry. They are used to treat mental illnesses like depression, schizophrenia, bipolar disorder, obsessive-compulsive disorder, attention deficit hyperactivity disorder, autism spectrum disorder, post-traumatic stress disorder, and others.

14. Sedative Drugs Sedatives calm the brain and reduce anxiety. They may be prescribed for people who suffer from insomnia, panic attacks, anxiety disorders, depression, and other conditions. Examples include alprazolam, amitriptyline, clonidine, diazepam, desipramine, fluoxetine, imipramine, isocarboxazid , lithium carbonate, maprotiline, methadone, nortriptyline, oxazepam, paroxetine, propranolol, sertraline, trazodone, valproic acid, venlafaxine, and xylazine.

15. Antidepressants An antidepressant works by increasing the levels of serotonin and norepinephrine in the brain. Serotonin is a neurotransmitter that helps regulate mood, while norepinephrine is a hormone that affects arousal and wakefulness. Antidepressants also work by blocking certain receptors in the brain.

16. Hypnotics A hypnotic alters consciousness by affecting the thalamus, hypothalamus, and cerebral cortex. A hypnotic may be used to induce relaxation, reduce pain, reduce insomnia, improve learning ability, enhance sexual performance, and increase appetite. Drugs have both short-term and long-term effects on the brain. Short-term effects occur within minutes to hours after taking the drug. Long-term effects take place over days, weeks, months, or even years.

17. Peripheral Nervous System The peripheral nervous system includes nerves outside the brain and spinal cord and consists of sensory neurons and motor neurons. Sensory neurons sense the environment and conduct signals to the brain that become a conscious perception of that stimulus. This conscious perception may lead to a motor response that is conducted from the brain to the peripheral nervous system via motor neurons to cause a movement. Motor neurons consist of the somatic nervous system that stimulates voluntary movement of muscles and the autonomic nervous system that controls involuntary responses.

18. Autonomic Nervous System The basis of autonomic pharmacology reflects the physiology of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS) to regulate involuntary reactions to stresses on multiorgan systems within the body. When a pathologic process is present that affects the homeostasis achieved between the SNS and PSNS in this process, either of these branches can become overactive while the other is excessively inhibited. This break in homeostasis results in various clinical manifestations that can range in severity from simply presenting rhinorrhea symptomology to fatal presentations like cardiovascular collapse. For a wide range of presentations and severity of pathologies, the agents classified in autonomic pharmacology are indicated to re-establish the homeostasis that the human body attempts to produce via the autonomic nervous system (ANS).

19. Autonomic Nervous System Within autonomic pharmacology, there are four specific categories of drugs based on how they affect the ANS: 1. Cholinomimetics/cholinesterase antagonists 2. Anticholinergics 3. Adrenoreceptor agonists/sympathomimetics 4. Adrenoreceptor antagonists

20. Cholinomimetics/cholinesterase antagonists A  parasympathomimetic drug , sometimes called a  cholinomimetic drug or  cholinergic receptor   stimulating agent , is a substance that stimulates the  parasympathetic nervous system  (PSNS). These chemicals are also called  cholinergic  drugs  because  acetylcholine  ( ACh ) is the  neurotransmitter  used by the PSNS. Chemicals in this family can act either directly by stimulating the  nicotinic  or  muscarinic  receptors (thus mimicking acetylcholine), or indirectly by inhibiting  cholinesterase , promoting acetylcholine release, or other mechanisms. Common uses of parasympathomimetics include  glaucoma ,  Sjögren syndrome  and  underactive bladder .

21. Anticholinergics Anticholinergics are a broad group of medicines that act on the neurotransmitter, acetylcholine. They are also called antispasmodics. By blocking the action of acetylcholine, anticholinergics prevent impulses from the parasympathetic nervous system from reaching smooth muscle and causing contractions, cramps or  spasms . Anticholinergics are used in the treatment of some gastrointestinal and bladder conditions. They may also be used in the treatment of some respiratory or movement disorders.

22. Adrenoreceptor agonists/sympathomimetics Adrenergic agonists  are autonomic nervous system drugs that stimulate the adrenergic receptors of the sympathetic nervous system (SNS), either directly (by reacting with receptor sites) or indirectly (by increasing norepinephrine levels). An adrenergic agonist is also called a  sympathomimetic  because it stimulates the effects of SNS.

23. Adrenoreceptor antagonists Adrenoreceptor antagonists, also known as sympatholytics , are a class of drugs that block the action of the sympathetic nervous system. They work by binding to adrenergic receptors without activating them, thereby preventing the endogenous catecholamines, such as epinephrine and norepinephrine, from binding to these receptors.

24. Cholinomimetics/Cholinesterase antagonists Bethanechol - postoperative and neurogenic ileus and urinary retention. Pilocarpine - glaucoma and alleviating the symptoms of Sjogren’s syndrome Nicotine - found in smoking cessation regimens Cholinesterase inhibitors (neostigmine, edrophonium, pyridostigmine, physostigmine) - the diagnosis and treatment of myasthenia gravis, maintenance treatment of Alzheimer disease, and specifically neostigmine used commonly with glycopyrrolate to reverse neuromuscular blockade in postoperative anesthesia practice

25. Anticholinergics Atropine - used in ACLS guidelines to correct bradyarrhythmias and in ophthalmic surgery as a retinal dilator Ipratropium and tiotropium - correct acute exacerbations of bronchospasm (asthma, COPD), as well as exacerbation prophylaxis for those conditions Scopolamine - prevents motion sickness and postoperative nausea/vomiting Oxybutynin - urge incontinence and postoperative bladder spasm Dicyclomine, glycopyrrolate - can be used for reducing diarrhea output in irritable bowel syndrome; glycopyrrolate can also be added to cholinesterase reversal of neuromuscular blockades in postoperative anesthesia care to prevent bronchospasm and is currently undergoing investigation as an adjunct treatment in COPD

26. Adrenoreceptor agonists/Sympathomimetics Clonidine - used as an antihypertensive Dobutamine, phenylephrine, epinephrine - used to correct severe hypotension in cardiogenic shock and acute heart failure exacerbation; epinephrine specifically also used in ACLS guidelines for non-shockable heart rhythms in cardiac arrest and rapid reversal of fatal anaphylactic reactions Albuterol - fast-acting bronchodilator used in acute asthma exacerbations Fenoldopam - corrects hypertension Bromocriptine - involved in the maintenance of Parkinson disease and conditions involving prolactinoma

27. Adrenoreceptor antagonists Phenoxybenzamine, phentolamine  - used to correct high catecholamine states Prazosin, doxazosin, terazosin, tamsulosin  - indicated to correct urinary retention in benign prostatic hyperplasia Beta-blockers (propranolol, metoprolol, labetalol, etc.)  - indicated for many cardiovascular conditions since they are in the classification of class II antiarrhythmics; these agents are used to manage tachyarrhythmias, hypertension, angina, heart failure, and migraine prophylaxis.  

28. THANK YOU FOR LISTENING!