Paramedic Care: Principles & Practice Volume 1 Introduction to Advanced Prehospital Care

1. Paramedic Care:Principles & Practice Volume 1Introduction to Advanced Prehospital Care

2. Chapter 9 General Principles of Pharmacology

3. Chapter 9, Part 2Drug Classifications

4. Part 2 Topics • Classifying Drugs • Drugs Used to Affect the Nervous System • Drugs Used to Affect the Cardiovascular System • Drugs Used to Affect the Respiratory System • Drugs Used to Affect the Gastrointestinal System • Drugs Used to Affect the Eyes • Drugs Used to Affect the Ears • Drugs Used to Affect the Endocrine System • Drugs Used to Treat Cancer • Drugs Used to Treat Infectious Diseases and Inflammation • Drugs Used to Affect the Skin • Drugs Used to Supplement the Diet • Drugs Used to Treat Poisoning and Overdoses

5. Classifying Drugs

6. Classifying Drugs • Drugs can be classified many ways: • Body system they affect • Mechanism of action • Indications • Source or by chemical class • A prototype best demonstrates the class’s common properties and illustrates its particular characteristics.

7. Drugs Used to Affect the Nervous System

8. Nervous System • Two major divisions • Central Nervous System • Brain and spinal cord • Peripheral nervous system • Outside of CNS

9. Analgesics and antagonists Anesthetics Anti-anxiety and sedative-hypnotic drugs Antiseizure or anti-epileptic drugs Central nervous system stimulants Psychotherapeutic medications Parkinson’s medications Central Nervous System Medications

10. Central Nervous System Medications • Analgesics and Antagonists • Analgesia is removal of pain • Two basic subclasses of analgesics • Opioid • Morphine is prototype • Nonopioid • Affects the production of prostaglandins and cyclooxygenase

11. Central Nervous System Medications • Analgesics and Antagonists (cont.) • Opioid antagonists • Competitively binds with opioid receptors • Naloxone is prototype • Adjunct medications • Enhancement of effect • Diazepam, lorazepam, phenergan • Agonist-Antagonist • Talwin, Stadol, and Nubain

12. Central Nervous System Medications • Anesthetics • Induces a state of anesthesia, or loss of sensation to touch or pain • As a group tend to cause respiratory, central nervous system (CNS), and cardiovascular depression • Given either by inhalation or injection • Paramedics primarily use these agents to assist with intubation in rapid sequence intubation

13. Central Nervous System Medications • Antianxiety and Sedative-Hypnotic Drugs • Used to decrease anxiety, induce amnesia, and assist sleeping and as part of a balanced approach to anesthesia • Sedation • Hypnosis • Two main pharmacologic classes are benzodiazepines and barbiturates

14. Central Nervous System Medications • Antianxiety and Sedative-Hypnotic Drugs • Benzodiazepines • Relatively safe and effective for treating general anxiety and insomnia • Hyperpolarize the membrane of CNS neurons • Benzodiazepines only increase the effectiveness of GABA, therefore, the amount of GABA present limits their effects • Flumazenil is available as antidote

15. Central Nervous System Medications • Antiseizure or Antiepileptic Drugs • Seizures are treated through several general mechanisms • Direct action on the sodium and calcium ion channels in the neural membranes • Dilantin inhibits inflow of sodium • Interact with the GABA receptor-chloride ion channel complex • Classes include benzodiazepines, barbiturates, hydantoins, succinimides, and miscellaneous medications such as valproic acid

16. Benzodiazepine Receptors

17. Central Nervous System Medications • Central Nervous System Stimulants • Two techniques may accomplish this: • Increasing the release or effectiveness of excitatory neurotransmitters • Decreasing the release or effectiveness of inhibitory neurotransmitters • Three pharmacologic classes: amphetamines, methylphenidates, and methylxanthines

18. Central Nervous System Medications • Central Nervous System Stimulants • Amphetamines • Most common uses are treating drowsiness and fatigue and suppressing the appetite • Methylphenidate • Commonly prescribed drug for attention deficit hyperactivity disorder (ADHD) • Methylxanthines • Caffeine, aminophylline, and theophylline

19. Central Nervous System Medications • Psychotherapeutic Medications • Treat mental dysfunction • Pathologies, seem to involve the monoamine neurotransmitters • Norepinephrine, dopamine, serotonin • Implicated in the control and regulation of emotions • Extrapyramidal symptoms are common side effects of antipsychotic medications

20. Central Nervous System Medications • Psychotherapeutic Medications • The two chief pharmaceutical classes are phenothiazines and butyrophenones. • Therapeutic effects appear to come from blocking the dopamine receptors. • Chlorpromazine (Thorazine) is the prototype phenothiazine. • Haloperidol (Haldol) is the prototype of the butyrophenones.

21. Central Nervous System Medications • Psychotherapeutic Medications • Antidepressants • Pharmaceutical interventions for this disease appear to increase the number of neurotransmitters released in the brain. • Tricyclic Anti-depressants • Act by blocking the reuptake of norepinephrine and serotonin • Selective serotonin reuptake inhibitors (SSRIs) • Selectively block the reuptake of serotonin

22. Tricyclic Antidepressants

23. SSRI Antidepressants

24. Central Nervous System Medications • Psychotherapeutic Medications • Monoamine oxidase inhibitors (MAOIs) • MAOIs inhibit monoamine oxidase and block the monoamines’ breakdown, thus increasing their availability. • MAOIs are not commonly used anymore. • The prototype of this class is phenelzine (Nardil).

25. Monoamine Oxidase Inhibitors

26. Central Nervous System Medications • Drugs Used to Treat Parkinson’s Disease • Caused by the destruction of dopamine-releasing neurons • Characterized by dyskinesia • Pharmacologic therapy for Parkinson’s disease seeks to restore the balance of dopamine and acetylcholine.

27. Central Nervous System Medications • Drugs Used to Treat Parkinson’s Disease • Levadopa and Sinemet • Given concomitantly • Amantadine • Promotes the release of dopamine from those dopamine-releasing neurons that remain unaffected by the disease • Anticholinergic drugs • Prototype anticholinergic medication is benztropine (Cogentin)

28. Autonomic Nervous System • Two functional divisions of the autonomic nervous system • Sympathetic • Fight or flight • Responds to stress • Parasympathetic • Controls vegetative functions such as digestion of food • Work in constant opposition to control organ responses

29. Autonomic Nervous System • Nerves of the autonomic nervous system exit the central nervous system. • Autonomic Ganglia • Preganglionic nerves • Postganglionic nerves Sympathetic Branch of the Autonomic Nervous System

30. Autonomic Nervous System • Synapse • No physical connection • Neurotransmitters • Acetylcholine • Norepinephrine

31. Nervous System Synapse Click here to view an animation on synapses.

32. Autonomic Nervous System Medications • Drugs affecting the parasympathetic system: • Cholinergics • Anticholinergics • Ganglionic blocking agents • Neuromuscular blocking agents • Ganglionic stimulating agents

33. Parasympathetic NS Drugs • Stimulation of the parasympathetic nervous system results in the following conditions: • Pupillary constriction • Secretion by digestive glands • Reduction in heart rate and cardiac contractile force • Bronchoconstriction • Increased smooth muscle activity along the digestive tract

34. Parasympathetic NS Drugs • Acetylcholine (ACh) • Two main types of ACh receptors • Nicotinic • Muscarinic • “Cholinergic” receptors • Cholinergics (parasympathomimetics) • Cholinergic blockers (parasympatholytics)

35. Parasympathetic NS Drugs • Cholinergics • Act either directly or indirectly • Direct-acting bind with ACh receptor sites • SLUDGE • Bethanechol (Urecholine) • Indirect-acting cholinergic drugs affect acetylcholinesterase • Neostigmine • Physostigmine

36. Parasympathetic NS Drugs • Anticholinergics • Muscarinic cholinergic antagonists • Competitively bind with muscarinic receptors without stimulating them • Prototype is Atropine • Nicotinic cholinergic antagonists • Block acetylcholine only at nicotinic sites • Ganglionic Blocking Agents •  Trimethaphan (Arfonad) and mecamylamine (Inversine)

37. Parasympathetic NS Drugs • Neuromuscular Blockers • Produces a state of paralysis without affecting consciousness • By competitive antagonism of nicotinic receptors at the neuromuscular junction • Either depolarizing or non-depolarizing agents • Succinylcholine (Anectine), a depolarizing agent, is commonly used

38. Parasympathetic NS Drugs • Ganglionic Stimulating Agents • Receptors reside at the ganglia of both the parasympathetic and sympathetic nervous systems. • Nicotine stimulates receptors. • Although, no medical use, it has helped understand the autonomic NS receptors • Causes sympathetic and parasympathetic response

39. Autonomic Nervous System Medications • Drugs Affecting the Sympathetic Nervous System • Adrenergic receptors • Adrenergic agonists • Adrenergic antagonists • Skeletal muscle relaxants

40. Sympathetic NS Drugs • Arises from the thoracic and lumbar regions of the spinal cord • Sympathetic ganglia • Chain ganglia • Collateral ganglia

41. Sympathetic NS Drugs • Adrenergic Receptors • Alpha Receptors • Beta Receptors • Sympathomimetics • Sympatholytics

42. Sympathetic NS Drugs • Adrenergic Agonists • Direct-acting agents • Indirect-acting agents • Adrenergic agents are chemically and functionally similar to the endogenous neurotransmitters • Norepinephrine, epinephrine, and dopamine • Dobutamine and isoproterenol

43. Sympathetic NS Drugs • Adrenergic Antagonists (cont.) • Adrenergic antagonists are remarkably selective in which receptor they affect • Alpha adrenergic antagonists • Phenoxybenzamine (Dibenzyline), prazosin (Minipress) • Beta adrenergic antagonists • Propranolol (Inderal), metoprolol (Lopressor), Atenolol (Tenormin)

45. Sympathetic NS Drugs • Skeletal Muscle Relaxants • Used to treat muscle spasm • Injury and disease causes • Prototype centrally acting skeletal muscle relaxant is baclofen (Lioresal) • Treats spasticity • Cyclobenzaprine (Flexeril) and carisoprodol (Soma) are commonly used for muscle spasms.

46. Drugs Used to Affect the Cardiovascular System

47. Review of A and P • Two-sided pump • 4 chambers • Systemic circulation • Pulmonary circulation

48. Cardiac Conduction System • Specialized cardiac tissue that generates electrical impulses • Conducts them rapidly throughout the heart • Automaticity

49. Action Potential of Cardiac Pacing Cells • Cyclic activity in the fast potentials has five phases • The slow potentials • Located in the dominant pacemakers • They depolarize differently • Result in self-depolarizing of SA and AV node

50. Dysrhythmia Generation • Result from either abnormal impulse formation (automaticity) or abnormal conductivity • Tachycardia and bradycardia are most common • An imbalance between the sympathetic and parasympathetic nervous systems