pharmacology test 1: adrenergic and cholinergic

Autonomic nervous system

-part of peripheral nervous system

-2 components:

--sympathetic also called adrenergic

--parasympathetic also called cholinergic

-ANS maintains homeostasis and equilibrium with body

--balance between effects maintains normal functioning

--all systems innervated by both components

fight or flight

-the SNS or sympathetic nervous system in your body's fight and flight regulator

-you can remember most of what the nervous system does when you think of what your body's response would be in an emergency

-the main neurotransmitters are

--norepinephrine (derived from dopamine)

--epinephrine

rest and digest

-parasympathetic system mainly responsible for "normal" status

--secretion of GI fluids, saliva

--slowing of HR

--peristalsis

--bladder emptying

--bowel movements

equilibrium

-if one system effects are decrease, the other system will have major influence

-in other words:

--if parasympathetic effects decreased or blocked - results are similar to adrenergic stimulation

--if sympathetic effects decreased or blocked - results are similar to parasympathetic stimulation

Alpha 1 (adrenergic) receptors

stimulators for flight*

-found primarily in smooth muscles located in

--blood vessels

--sphincters of GI&GU tracts

-stimulation causes smooth muscle constriction:

--to increase your BP and heart contractility (think you would need to have your heart beating harder to help you run from your enemy)

--constriction of urinary bladder sphincter and GI tract (you wouldn't need to use the bathroom or digest your meal when your running from your enemy)

--goosebumps

vasoconstriction

increased BP

contracted piloerection muscles

pupil dilation

thickened salivary secretions

closure of urinary bladder sphincter

male sexual emission

Alpha 2

-inhibits release of norepinephrine

--decreases vasoconstriction

--causes decreased BP

-moderation of insulin release from pancreas

negative feedback control of norepinephrine release from presynaptic neuron

Beta 1

-located primarily in cardiac muscle

--you need your heart pumping faster and harder to increase cardiac output to run away from threat

-stimulation increases heart rate and force of contraction

-some blood pressure medications beta adrenergic blockers work to lower BP and control heart rate by blocking these receptors

-causes lipolysis in peripheral tissues

increased HR

increased conduction through the atrioventricular node

increased myocardial contraction

lipolysis in peripheral tissues

Beta 2

airway response

-mainly in bronchial smooth muscle (lungs)**, also in:

--arterioles of skeletal muscles

--and dertusor and uterine muscles

-stimulation

--relaxation of smooth muscles of lung = bronchodilation (you need more air in lungs to run)

-this is the site of action for asthma medication and how "bronchodilators" work

-use beta 2 agonist for people with respiratory disease, preterm labor

-increase blood flow to skeletal muscles

-relaxation of detrusor and uterine muscle, (you wouldn't have a baby or wet your pants on the run)

-breakdown of glycogen from liver, release glucagon from pancreas = increased blood glucose = energy to run away

-decrease GI muscle tone, secretions

vasodilation

increased breakdown of muscle and liver glycogen

release of glucagon from the pancreas

relaxation of uterine smooth muscle

decreased GI muscle tone and activity

decreased GI secretions

relaxation of urinary bladder detrusor muscle

neurotransmitters

norepinephrine

epinephrine

dopamine

drugs that mimic the effect of norepinephrine

sympathomimetics

adrenergic agonists

drugs that block the effects of norepinephrine

sympatholytics

adrenergic blockers AKA adrenergic antagonists

adrenergic drug - prototype

-affects both alpha and veta receptors

-naturally occurring catecholamine

-sympathomimetic for tx of shock

--mimics norepinephrine

--increases BP, heart rate

---stimulation = increased cardiac output = perfusion

--located in renal, mesenteric GI, coronary, cerebral arteries

---stimulation = vessels dilate and increase blood flow to these areas

Dopamine

given in emergent situations when perfusion is decreased to these organs

-effects are dose dependent***

--low dose used to increase renal blood flow

--higher dose used to control BP

--in high doses, dopamine acts like epinephrine

epinephrine

ADRENALIN

-very potent

-stimulates all adrenergic receptors

-causes increased force of myocardium contractions (inotrope)

-causes blood vessels to constrict = increased BP & HR

-dilates bronchial smooth muscle

used in emergencies

-anaphylaxis

-cardiac arrest

-bronchospasm (for acute asthma)

CAN BE GIVE SQ, IV, TOPICALLY, OR BY INHALATION

-dangerous because of potency, damage to organs is some cases

-high doses can lead to cardiac dysrhythmias so ECG monitored

-renal vaso constriction can decrease perfusion and lead to decreased urine output

-expected side effect = pallor

--all blood is shunted to vital organs

ephedrine

BETA 2 STIMULATOR

-synthetic catecholamine/sympathomimetic (stimulator)

-not as potent as epinephrine

-since it stimulates the beta 2 receptors, dilating bronchial tubes, it is useful in mild form of asthma

-can be used as part of local anesthesia to keep drug localized by constricting blood vessels

*FYI EPHEDRINE AND PSEUDOEPHEDRINE USED AS COLD/ALLERGY MED TO CONSTRICT SMALL VESSELS TO DECREASE RUNNY NOSE, SINUS CONGESTION = DANGER FOR FOLKS WITH CARDIAC, BP, THYROID, DM

-OTC but must sign in ohio (being used to mix with illegal drugs)

Clonidine (catapress)

alpha specific agonist

stimulate Alpha 2 to vasodilate

decrease BP

withdrawal form opiates

Phenylephrine (neo-synephrine)

alpha specific agonist

stimulate alpha 1 to vasoconstrict

increase BP

common in allergy, decongestant preparations

Albuterol (proventil)

beta specific

selective for beta 2 receptors

-action is purely bronchodilation

-fewer side effects for asthmatics

-if dose increased, begin to effect on beta 1 receptors

--increased HR, tremors, restlessness

-given PO, inhalation

-treats bronchospasm - very effective for acute asthma

nursing considerations for adrenergic agonists

-monitor vital signs

-contraindicated/caution if hx of dysrhythmias, high blood pressure, thyroid disease

-beta blockers decrease the effect of epinephrine/norephrine

caution patient about over the counter cold, allergy type meds, many contain sympathomimetic drugs

adrenergic blockers

Effects of adrenergic blockers at receptor sites

Selective and nonselective alpha blockers

Alpha 1 blocker

-vaso dilate to decrease BP, prostate contraction, bladder contraction

-used to treat

--benign prostate hypertrophy

hypertension if with other meds

-side effects:

--cardiac dysrthythmias, flushing, hypotension, reflex tachycardia

Beta adrenergic blockers

-drugs can be selective or nonselective ---- they block one type of receptor or > one type of receptor

--if only one problem use selective if more than one problem use nonselective

-we may want to treat specific conditions so drugs are chosen based on selectivity

-for example we want to treat heart or blood pressure in patient who has respiratory disease: a non selective drug would not only block the cardiac response but also block the sympathetic response in airways which is bronchodilation and could cause patient to have respiratory distress

non selective blockers

block beta 1&2

Propranolol HCl (inderal)

-used to treat hypertension, heart rhythm, stage fright

-contraindications:

--asthma and COPD - may cause bronchoconstriction

-diabetes mellitus = would complicate peripheral circulation and interfere with signs of hypoglycemia

selective blockers

block beta 1

Metoprolol (lopressor), atenolol (tenormin)

-used to treat hypertension, heart rhythm

-good for control of heart rate

-chronic angina

common side effects/ adverse reactions of beta adernergic blockers

bradycardia

hypotension

headaches

additive effect with other BP meds

less frequent hyperglycemia/hypoglycemia agranulocytosis

nursing responsibilities for beta blockers

-monitor HR, BP

-caution with IV - slow,lower dose, EKG monitoring

-assess fall risk (orthostatic hypotension risk)

-especially if other BP meds

-caution with DM - glucagon it increase glucose

-teach pt to not stop drug abruptly (may have rebound HTN)

Parasympathetic (cholinergic) nervous system actions

Used for maintenance and to promote balance in the nervous system, the opposite of the SNS

2groups of drugs we will review

cholinergics AKA parasympathomimetics

anticholinergics AKA parasympatholytics

PNS functions to

promotes body waste elimination:

-increased intestinal and bladder muscle tone

-relax of anus and uretheral sphincter muscles

-increased sweating

promoses energy constervation by decreaseing HR & BP

pupil constriction

promotes nutrient utilization by

-increased gastric motility and acid secretion

-increased salivation, releasing digestive fluids from gallbladder

comparison of adrenergic and cholinergic drugs

stimulation

-Sympathetic/ adernergic agoinists

--increase HR, dilate pupils, constrict bronchiole, uterine contraction

-parasympathetic/ cholinergic drugs

--decrease HR & BP, constrict pupil, constrict bronchiole, increase bladder contraction, increase peristalsis

blocker

-parasympatholytic/ anticholinergic - effects similar to sympathetic/adernergic drug

-sympatholytic/ adrenergic blocker - effects similar to cholinergic drug

Cholinergic/ Parasympathomimetics

similar to adrenergic (stimulator)

-neuro transmitter = Acetylcholine (Ach)

-cholinesterase - enzyme that stops acetylcholine

--an indirect acting drug blocks cholinesterase and allows Ach to bind to receptor

Muscarinic

receptor of paraysmypathetic

-found in visceral effector organs

-GI tract, bladder, heart, sweat glands, some blood vessels

-stimulation = increased motility, heart rate, bladder contraction, increased secretions

nicotinic

receptor of parasympathetic

-found in CNS, adrenal medulla, neuromuscular junction

-stimulation = increased muscle contraction, signs and symptoms of stress response, release of epinephrine and norephrine

Bethanechol choloride (urecholine)

direct acting cholinergic drugs

prototype drug

-acts at muscarinic receptor to increase urination and GI motility

-void in 1-2 hrs, achieve BM

-can be SQ, oral, not IV

side effects/ adverse reactions

-hypotension, bradycardia, excessive salivation, increased secretion of gastric acid, bronchoconstriction, abdominal cramps

-DO NOT GIVE if bowel or bladder obstruction

*not used all that often

indirect acting cholinergic drugs

-also called chokinesterase (ChE) inhibitors, and acetylcholinersterase (AchE) inhibitiors

--allows AcH to attach to reeptor, to activate muscarinic, nicotinic receptors

-Uses:

--promote muscle contraction in Myasthenia Gravis

--reverse neuromuscular blockers

--delay prgression of Alzheimer's demenita

-S.E.

--bradycardia, asthma, peptic ulcers

Cholinesterase inhibitors

Reversible (short acting)

-uses:

--glaucoma by causing pupillary constriction**

---i.e. pilocarpine

--myasthenia gravis to improve muscle strength**

---ie. pyridostigmine (mestinon)

Irreversible

-long action

-used for pupil constriction

-used as insecticide (organophospates) wargases

Atropine can reverse effects!

--it is an anticholinergic drug

Atropine

anticholinergic prototype drug

-preop med - reduces salivation

-antispasmodic in GI system

-stimulate heart rate (ACLS drug) - blocks vagus stimulation to cardiac muscle

-antidote for nerve gas (organophosphate)

-when cholinergic receptors are blocked it allows sympathetic system to dominate

other anticholinergic drug uses

-smooth muscle relaxants:

--treat overactive bladder

---prototype drug: tolterodinem (detrol, Detrol LA)

-treat respiratory disease, bronchospasm

--ipratropium (atrovent)

-antiparkinson

--artane = prototype

--suppresses tremors and drooling

-synthetic - probanthine to decrease GI motility

-scopalamine can be used for motion sickness

Side effects/ adverse reactions of anticholinergics

-tachycardia

dry mouth

nasal congestion

abdominal distention

palpitations

photophobia

blurred vision

flushing

urinary retention

constipation

unable to sweat

nursing responsibilities

-teach safety

--visual changes (blurred, photophobia)

--inability to perspire

-monitor bowel and bladder function

-assess vital signs - HR,BP

-how to decrease symptoms

--dry mouth - hard candy, artificial saliva

--constipation - fluids, fiber, stool softeners

--dry eyes - artificial tears

-- take in evening before bedtime