PHARMACOLOGY part 2 Flashcards
botulinum toxin prevents the release of ___
acetylcholine
hemicholinium prevents the synthesis of ___
acetylcholine
why is it almost impossible to enhance the destruction of acetylcholine?
because it is broken down almost instantaneously
neostigmine is a ___ inhibitor
cholinesterase (like physostigmine)
___ is a synthetic atropine-like drug used to dry salivation and as an antispasmodic agent
propantheline (probanthine)
what is phenobarbital?
a barbiturate anticonvulsant
curarine is a ___ receptor blocker that causes ___
- nicotinic
- muscular paralysis
edrophonium is an anticholinesterase used to treat ___
myasthenia gravis
gallamine is a long acting neuromuscular junction blocker used for ___
paralysis
all paralysis inducing drugs act via ___ receptor at the ___
- nicotinic
- neuromuscular junction
salivation is typically considered to be a ___ response
cholinergic
cholinergic agonists are useful in treating xerostomia except in which patients?
those who have been subject to head and neck radiation therapy, due to nonfunctional salivary gland tissue
ephedrine is a mixed acting adrenergic ___
agonist
what are the cholinergic stimulation effects of the eye?
miosis (pinpoint pupil) and reduction of intraocular pressure
what are the cholinergic stimulation effects of the cardiovascular system?
- bradycardia
- vasodilation, but only from injected cholinergic agents, since the muscarinic receptors on the vascular smooth muscle has no neural input
what are the cholinergic stimulation effects of the GI tract?
increased spasmodic activity, increased salivation and acid secretion (overdose: nausea, vomiting, diarrhea)
what are the cholinergic stimulation effects of the urinary tract?
increased urination
what are the cholinergic stimulation effects of the respiratory system?
bronchoconstriction
what are the cholinergic stimulation effects of the glandular system?
lacrimation and sweating
what are the cholinergic stimulation effects of skeletal muscle?
tremor and ataxia (overdose: muscle weakness, cramps and fasciculations)
what are the anticholinergic (antimuscarninic) actions of the eye?
mydriasis and loss of accomodation, and increase of intraocular pressure
what are the anticholinergic (antimuscarninic) actions of the cardiovascular system?
increased heart rate (overdose: tachycardia)
what are the anticholinergic (antimuscarninic) actions of the GI tract?
decreased spasmodic activity, decreased salivation and acid secretion
what are the anticholinergic (antimuscarninic) actions of the urinary tract?
decreased urination
what are the anticholinergic (antimuscarninic) actions of the glandular system?
decreased lacrimation, decreased sweating (overdose: hot, dry skin, hyperthermia)
what are the anticholinergic (antimuscarninic) actions of the skeletal muscle?
no effects
what are the anticholinergic (antimuscarninic) actions of the CNS?
- tertiary amines such as atropine get into the brain and cause restlessness, headache, excitement, hallucinations, and delirium
- quaternary amines like methantheline and propantheline only have peripheral actions
a ___ blocker, since it acts by preventing ACh from stimulating nicotinic receptors at the ganglia level will have both anticholinergic and antiadrenergic effects
ganglionic
what is the acronym for remembering the effects of cholinergic stimulation?
- SLUD
- increased salivation, lacrimation, urination, and defecation
- the heart is the exception in that activity or heart rate is decreased (bradycardia)
organophosphates kill you from too much ___ stimulation
cholinergic (SLUD + bradycardia)
what is the affect of glandular secretions to atropine?
- glandular secretions are generally under cholinergic control, so sweating and salivation are greatly reduced by the anticholinergic drug atropine
- side effects of atropine could include burning dry mouth and hyperthermia
what are examples of a cholinergic overdose?
nausea, vomiting, and orthostatic hypotension
why is scopolamine used for sedation but atropine is not?
- atropine overdose causes CNS excitation and tachycardia
- atropine is actually useful in surgery in cases where reversal of bradycardia is necessary
what is the immediate cause of death as a result of organophosphate toxicity?
respiratory paralysis, which results from the stimulation of nicotinic receptors at the neuromsucular junction, resulting in paralysis of skeletal muscles
which drug classes have potent anticholinergic activity?
- prototypes atropine and scopolamine
- tricyclic antidepressants
- H1 antihistamines
- opioid analgesics
what is the mechanism of action of adrenergic receptor blockers?
alpha or beta adrenergic drugs such as prazosin or propranolol act by competitive inhibition of postjunctional adrenergic receptors
what are the 4 drugs that inhibit the action of adrenergic nerves, and what is their mechanism of action?
- reserpine: depletes NE by inhibiting reuptake
- guanethidine: inhibits the release of catecholamines
- alpha methyldopa: acts centrally as a false neurotransmitter which gets taken up into storage vesicles and released with NE, thus decreasing sympathetic activity
- clonidine: stimulates alpha2 receptors in the CNS with a resulting decrease in sympathetic outflow
what are the 3 mechanisms of action of indirect acting sympathomimetic drugs?
- amphetamine, tyramine, and ephedrine act by stimulating the release of stored NE
- TCAs and cocaine block reuptake
- MAOIs block enzymatic destruction
what is the action of epinephrine in the presence of an alpha blocker?
- “epinephrine reversal”
- int he presence of an alpha blocker (usually prazosin, but chlorpromazine may also be given), epi causes a decrease in blood pressure rather than increased because beta mediated vasodilation predominates
what is the action of epinephrine in the presence of NE?
- vagal reflex
- injection of a pressor dose of NE may result in decreased heart rate due to activation of baroreceptors which stimulate vagal reflex to reduce heart rate
- vagal reflex is blocked by atropine
what is the result of alpha-1 receptor stimulation?
vasoconstriction, urinary retention, mydriasis
what is the result of beta receptor stimulation?
increased heart rate (B1), bronchodilation (B2), and vasodilation (B2)
what is the result of alpha-1 block?
vasodilation
what is the result of beta block?
decreased heart rate (B1), bronchoconstriction (B2)
parkinson’s is a result of ___ deficiency in the brain
- dopamine
- therefore, the remedy is to increase dopamine in the brain
what is the treatment for parkinson’s?
- levodopa with carbidopa
- injected DA doesn’t cross the BBB, but levodopa, a precursor to DA, does
- carbidopa is given with levodopa to block dopa decarboxylase activity in the periphery, which in the absence of carbidopa, converts levodopa to DA in the periphery, decreasing the amount of levodopa that ends up in the brain
what are the side effects of levodopa?
- levodopa is a sympathomimetic and will produce sympathetic stimulation in the periphery
- development of abnormal facial movement, nausea and vomiting, cardiac arrhythmias, and mental disturbances are all associated with levodopa therapy
___ and ___ are the only centrally acting antihypertensives, reducing sympathetic outflow via alpha-1 agonist action
methyldopa and clonidine
what is the mechanism of action of amphetamine?
- indirect-acting sympathomimetic (acts like NE)
- causes release of neurotransmitter
what are the mechanisms of action of cocaine, TCAs, ephedrine, and MAOIs?
- cocaine: reuptake inhibition and release
- TCAs: reuptake inhibition
- ephedrine: causes release but also acts at receptor itself
- MAOIs: block NT degradation
what are the affects of the injection of a sympathomimetic drug?
- stimulates both alpha and beta receptors
- alpha-receptor stimulation produces vasoconstriction, increased systolic and diastolic pressure, and reflex tachycardia
which drug can be used in pretreatment to prevent a response from amphetamine?
reserpine, because it causes depletion of NE from storage sites, and therefore NE cannot be released by amphetamine
what are the effects of alpha-1 agonists?
increased smooth muscle tone, so vasoconstriction leading to increased blood pressure
what are the effects of alpha-2 agonists?
given orally they cause hypotension by reducing sympathetic outflow from the CNS
what are the effects of beta-1 stimulation?
increased cardiac rate and force of contraction, thus positive inotropic and chronotropic actions
what are the effects of beta-2 stimulation?
dilation of skeletal muscle blood vessels and bronchi or relaxation of bronchiolar smooth muscle
what are the effects of adrenergic stimulation of the following organs: eye, heart, vascular smooth muscle, skeletal muscle vessels, bronchiolar smooth muscle, and sweat glands
- eye: mydriasis or relaxation of ciliary muscle
- heart: acceleration, increased contractility
- vascular smooth muscle: vasoconstriction
- skeletal muscle vessels: relaxation or dilation
- bronchiolar smooth muscle: relaxation/bronchodilation
- sweat glands: sweating
stimulation of beta-1 receptors in the cardiac muscle will increase ___ BP, and beta-2 stimulation will decrease ___ BP
- systolic
- beta-2 stimulation will dilate vessels going to the liver and skeletal muscle, producing a decrease in diastolic BP
what action does epinephrine have where it is useful in the treatment of acute bronchospasm?
it causes bronchodilation
injection of epi usually causes a rise in blood pressure due to what 3 things?
- myocardial stimulation that increases ventricular contraction
- an increase in heart rate
- vasoconstriction due to alpha receptor stimulation (most important)
why are vasoconstrictors included in local anesthetic preparations?
- prolong and increase the depth of anesthesia by retaining the anesthetic in the area injected
- reduce the toxic effect of the drug by delaying its absorption into the general circulation
- to render the area of injection less hemorrhagic