Sympathomimetics Flashcards
as bronchodilators
beta-2 stimulants used to relieve bronchoconstriction in chronic obstructive pulmonary disease (COPD)
receptors involved in bronchodilators
Beta-2
alpha-1
beta-1 action-> side effect
leading cause of death
COPD
emphysema
WBC proteolytic destruction of alveolar wall
asthma
allergic or intrinsic precipitated by cold, gasoline, fresh paint
bronchoeictasis
dilated bronchi due to damage by infection
chronic bronchitis
due to infection
sympathetic bronchodilators
can be used to diagnose cause of airway constriction
- may be due to inflammation of bronchiolar spasms
- beta-2 stimulants act in seconds
epinephrine works on
alpha-1, beta-1, beta-2
albuterol
beta-2
metaproterenol
beta-2
salmeterol
beta-2
-use with steroids
what else do bronchodilators do?
increase ciliary activity, inhibit histamine, leukotriene release
beta-2 agonist drugs of choice
- tolerance
- receptor-down regulation prevented or even partly revered with steroids
precautions for adrenergic bronchodilators
- benign essential tremor (from beta-2 stimulation)
- feelings of anxiety may limit use
- increased blood sugar: alpha1/beta2 receptors mobilize liver glycogen
- dry pharyngeal membranes-> problem with epinephrine (vasoconstriction)
nasal decongestants
alpha-1 agonists constrict dilated blood vessels and relieve nasal stiffness and headache
nasal decongestant drugs
- phenylephrine
- pseuoephedrine
- oxymetazoline
phenylephrine
give p.o, nose drops or spray
-p.o dose advantages
pseuoephedrine
still widely available
CNS stimulant
oxymetazoline
long duration, 12 hours
adverse effects to nasal decongestants
transient burning
rebound congestion
chemical rhinitis
CNS depression, hypotension (imidazoline)
uses of sympathomimetisc in eye
Mydriasis
relieve redness, itching
-in allergic hyperemia of conjunctival membrane
uses of sympathomimetisc in eye: Mydriasis
phenylephrine
- duration 3 hours, advantage over atropine
- mydriasis without cycloplegia
uses of sympathomimetisc in eye: to relieve itching and redness
oxymetazoline
adrenergics in acute hypersensitivity
involve foods, pollon, drugs, animals
- beta-2 stimulants inhibit antigen-induced histamine release
- epinephrine used
sympathomimetics in hypotension
"pressor" effects -below 40 mmHg diastolic or 50 systolic -critical decrease in flow to heart, brain, gut, liver, kidney -clinical situations showing decrease BP general and spinal anesthesia drug overdose acute renal failure
what are the two ways to increase blood pressure
- increased cardiac output (beta-1)
2. increased peripheral resistance (alpha-1)
norepinephrine
lasts about 2 mins
does nothing to CO
increases PR
alpha-1 stimulant: Phenylephrin
20 mins
decrease CO
increases PR
dopamine
lasts about 2 mins
increases CO
decreases PR
dobutamine
lasts about 2 mins
increases CO
does nothing to PR
sympathomimetic pressor agents
- short acting ones are substrates for NET and ENT
- long acting-> smoother pressure control
- dopamine-> some beta-1, and dilation of renal, coronary and mesenteric beds (D1 receptors)
- dobutamine-> beta-1 but little increase in rate
precautions in using pressor agents
- hyperthyroidism (excess receptors)
- necrosis on prolonged vasoconstriction: Liver, kidney
what are some diseases that show adrenergic deficiency
PAF: pure autonomic failure
POTS: postural tachycardia syndrome
MSA: multiple systems atrophy
PAF
disease of post-ganglionic sympathetic nerves
- onset middle age
- more common in men
POTS
50% antecedent viral illness
-4 times more common in females
MSA
autoimmune degeneration ANS centrally
-twice as common in men
adrenergics in sympathetic deficiency
- correct postural hypotension, urinary incontinence and retrograde ejaculation
mitodrine: alpha-1 agonist, give early in the day avoid nocturnal hypertension
sympathomimetics as cardiac stimulants
In A-V block to prevent loss of consciousness
-“Stokes Adams” syndrome
-some patients alternate between 2nd and 3rd degree block (skipped beats or complete block)
-definitive treatment-> pacemaker
After bypass surgery
-iv epinephrine, isoproterenol, dobutamine, dopamine
indirect-acting sympathomimetics
- Tyramine in some cheese and sausage
- Dopamine
- Pseudoephedrine, ephedrine