Pharmacology:(ii)Pulmonary drugs Flashcards
What is the mechanism of action of methyxanthines(e.g theophylline, aminophylline)?(4)
What are the other effects of methylxanthines?(4)
- Direct smooth muscle relaxation of bronchi and pulomonary vasculature(bronchodilation and vasodilation)
- Competitive inhibition of phosphodiesterase; increases cAMP levels, which increase endogenous epinephrine
- Competitive antagonism of adenosine
- Interference with calcium mobilisation
a. Inhibit histamine release(inhibition of mast cell degranulation) and inflammatory mediator release
b. Increase mucociliary clearance
c. prevent microvascular leakage
d. Increase strength of respiratory muscles
What are the indications of methylxanthines?
- Bronchospasm
- Extended released formulations available
What are the side effects of methylxanthines?
- CNS signs(excitement, seizures, restlessness)
- GI upset
- Polyuria
- Polydipsia
- Narrow therapeutic range
What are the contraindications of methylxanthines?
- Cardiac arrhythmias
- Hypertension
- Gastric ulcers
- Renal or hepatic disease
- Hyperthyroidism
What is the mechanism of action of beta-2 adrenergic agonists?(3)
Give examples of beta-2 adrenergic agonists.
- Relaxation of bronchial smooth muscle
a. Activation of beta-2 adrenerguc receptors
b. Increased cAMP via activation of adenylyl cyclase
(1) ctivation of protein kinase (bronchodilation)
(2) Inhibition of inflammatory cell mediator release - Stimulation of secretion of mucus
- Enhance mucociliary clearance.
Terbutaline, albuterol and epinephrine
What is the mechanism of action of terbutaline, albuterol?
Selective beta-2 adrenergic agonists
What are the indications of terbutaline, albuterol?
- Bronchospasm
- Albuterol available as inhaler
What are the side effects of terbutaline, albuterol?
-Tremors, tachycardia, CNS excitement(secondary to non-specific beta-1 receptor activation at high doses)
What are the contraindications of terbutaline, albuterol?(6)
-Cardiac arrhythmias
-Hypertension
-Seizures
-Hypertension
-Seizures
-Hyperthyroidism
NOTE: Use with caution
What is the mechanism of action of epinephrine?
-Non selective beta-adrenergic agonists. Stimulates beta-1, beta-2 and alpha adrenergic receptors
What are the indications of epinephrine?
a. Allergic reactions(insect bites, urticaria)
b. Acute severe bronchospasm
What are the side effects of epinephrine?
Tachycardia
- Vasoconstriction
- Hypertension(result of beta-1 and beta-2 adrenergic receptor activation)
Give 2 examples of an opioid cough suppressant and describe its mechanism of action.
Butorphanol
Hydrocodone
-Mechanism of action:
a.Synthetic opioid
b.Mixed agonist-antagonist: kappa-receptor agonist, weak u-receptor antagonist
c.Suppresses afferent input into coughing center(medulla)
What are the indications of butorphanol?
Antitussive in dogs with minimal to no sedation; mild analgesia
What are the side effects of butorphanol?
- Sedation(higher doses)
- Significant hepatic first-pass effect(requires higher oral dosing)
- Minimal cardiac and respiratory depression
