Receptor-Drug Interaction
Produces the maximum effect
Full Agonist
direct acting a1-adrenergic
treats urinary incontinence by constricting the urinary bladder sphincter
Whats the drug? Side effects?
Phenylpropanolamine (PROIN)
tachycardia, High BP
non-selective B- adrenergic
used to help with bradycardia & heart block
Drug name? Side effects?
Isoproterenol
palpations, tachycardia, arrhythmias & cardiac ischemia
non-selective (reversible)
reverse effects of xylazine in large animals
Tolazoline
cardiac arrythmias
Are there any selective B2 adrenergic blockers that we discussed?
no
bound covalently to the enzyme-inhibitor complex, efficacy is reduced
Competitive (Irreversible) Antagonist
direct-acting a1-adrenergic
used as a nasal decongestant, mydriatic agent (ocular), also a vasopressor. What is the drug? Potential side effects?
Phenylephrine
High BP
G-protein-coupled membrane receptor (GPCR) stimulation leads to bronchodilation
Beta 2-AR
relaxation of smooth muscles
selective a2
reversal agent of xylazine and detomidine (IV); large animal
Drug?
Yohimbine
Selective B1 blocker
antihypertensive/antiarrthymic to slow sinus rate
drug? side effects?
Atenolol
Binds to and activates the receptor but produces a sub-maximal effect.
Partial Agonist
a2-adrenergic receptor
anesthetic premed, sedation IV; used as an emetic in cats only
Drug name? Potential Side effects?
Xylazine
bradycardia, myocardial depression, heart conduction disturbances
used for congestive heart failure (accumulated blood in veins)
increases AV conductions
Drug name? B1 or B2?
B1- adrenergic
Dobutamine
selective a1
hypertension, benign prostate hypertrophy
drug? potential side effects?
Prazosin
hypotension, reflex tachycardia = less significant
non-selective
decrease HR, force contractions & BP
Drug? Side effects?
Propranolol
bronchoconstriction, cardiac arrythmias, hypoglycemia
Inhibitor acts on the same receptor as the drug. Can be surmounted by increasing the concentration of the drug.
Competitive (Reversible) Antagonist
a2-adrenergic receptor
sedation and anesthetic premed, IV
large animal & horses combined with ketamine
(2 options) Drug name? Side effects?
Detomidine & Romifidine
bradycardia, myocardial depression, & heart conduction disturbances (2nd degree AV blocks)
B2-adrenergic receptor
bronchodilator (side effects include tachycardia)
Drug? Administration?
Terbutaline
tablets, elixir & injectable SQ
selective A2 antagonist
IV is not tolerated by small animals, IM use
Drug? Therapeutic Use?
Atipamezole
reversal agent for dexmedetomidine & medetomidine in dogs
non-selective
treats wide angle glaucoma
Timolol
a drug that acts at the same receptor as agonist but produces an opposite pharmacological effect
Inverse agonist
a2-adrenergic receptor
used to treat behavioral disorders
Drug name? Side effects?
Clonidine
sedation, bradycardia, rebound hypertension
three B2-adrenergic receptor drugs that can be administered orally
Name one of the drugs. Which drug is banned in food producing animals, and why?
Salbutamol (oral/aerosol)
Clenbuterol (IV/Oral) - asthma in horses: performance-enhancing effects in human consumption
Salmeterol (dry inhalation powder)
non-selective/ irreversible!!
pheochromocytoma, management of benign prostatic obstruction
Drug? Side effects?
Phenoxybenzamine
postural hypotension accompanied by reflex tachycardia & arrhythmias
non-selective
anti-arrythmic
Sotalol