Respiratory pharmacology - drugs affecting bronchiole diameter Flashcards
Give examples of types of respiratory drugs
Drugs affecting bronchiole diameter Drugs affecting respiratory centre Anti-tussives Decongestants Expectorants Mucolytics Surfactants
Which 2 systems, 1 reflex and 1 receptor affect bronchial diameter?
Sympathetic system
Parasympathetic system
Nasopulmonary reflex
Non-adrenergic non-cholinergic receptors
Do the symp and parasympathetic NS cause broncho dilation or bronchoconstriction? What effect do they have on mucous?
Sympathetic - broncho dilation, increased mucociliary clearance
Parasympathetic - bronchoconstriction and increased mucous production
Which receptors are responsible for causing smooth muscle dilation (broncho dilation) by the sympathetic nervous system?
B2 adrenoreceptors
Which receptors are responsible for parasympathetic stimulation (bronchoconstriction and increased mucous secretion)? Stimulation of which nerve is responsible for this?
Muscarinic receptors
Via vagus nerve
What are the 3 broad classes of drugs affecting bronchial diameter?
Adrenegic drugs
Cholinergic drugs
Drugs directly acting on smooth muscle
Adrenoreceptor agonists are adrenergic drugs. What do they stimulate and cause? What systemic adrenoreceptor agonists (neurotransmitters) are found naturally in the body?
Stimulate sympathetic NS and cause bronchodilation
Noradrenaline
Adrenaline
Give an example of an adrenoreceptor agonist drug. What condition can this be given for? What are the side effects?
terbutaline
Acute bronchoconstriction
Peripheral vasoconstriction, tachycardia, sweating, excitement
In which patients would you need to consider giving adrenaline to?
Patients with blood pressure abnormalities or tachycardia
Using 2 adrenoreceptor agonist drugs together leads to a higher chance of side effects, as adrenoreceptor agonists usually have lots of side effects. Why?
Non-selective agonists
Stimulate sympathetic nervous system systemically
Give 4 examples of adrenoreceptor agonists
Noradrenaline
Adrenaline
Ephedrine
Isoproterenol
What is a property of B2 selective agonists that make them more preferable than adrenoreceptor agonists?
Selective - have varying range of selectivity
Therefore less side effects
Give 3 examples of B2 selective agonists
Clenbuterol
Salbutamol (albuterol)
Terbutaline
How can terbutaline and salbutamol be administered? What effect do these administration methods have on terbutaline uptake?
Oral - less uptake as higher pKA
Inhalation - fast and complete uptake
How is clenbuterol administered? What is an important feature of this drug?
Orally
Excreted in urine for 12 days
What effect do adrenoreceptor antagonists have on the bronchi?
Opposite to agonist - bronchoconstriction
Give an example of an adrenoreceptor antagonist
What is this drug primarily used for? When might it be contraindicated?
Beta blockers
Treatment of tachycardia
Asthma or chronic bronchitis as causes bronchoconstriction
What type of drugs are anticholinergics and what do they cause?
Parasympathetic antagonists
Bronchodilation, decreased mucous production, reduced response to irritation, pulmonary vasoconstriction
What are the side effects of anticholinergics/parasympathetic antagonists?
Tachycardia Decreased GI motility mydriasis Hypertension Mydriasis
Anticholinergic drugs/parasympathetic antagonists are rarely used in practice except for which drug and why? How is it administered?
Ipratropium
Topical administration so reduced side effects
What effect do cholinergic drugs have?
Bronchoconstriction
Increased mucous secretion
Cholinergic drugs have limited effect on respiratory system. Give 2 examples of cholinergic drugs and what are they used for?
Pilocarpine- topically on eye
Bethanechol - systemically for smooth muscle contraction
How do indirect cholinergic work?
Inhibit AChE
Increase acetylcholine at synapse
What class of drugs act directly on smooth muscle to affect bronchiole diameter?
Methylxanthines
Describe 3 properties of methylxanthine drugs (what they do)
PDE inhibitors
Block degradation of cAMP
Adenosine antagonists (further increase cAMP)
Methylxanthine drugs cause an increased level of cAMP. What effect does increased cAMP have?
Bronchodilation
Inhibition of inflammatory mediators
Increased mucociliary clearance (cilia beat cranial faster - to pharynx to swallow)
Methylxanthine drugs have desirable effects for conditions such as asthma and acute bronchitis. What are the side effects of methylxanthines?
Tachycardia
Excitability
Seizures
Decreased GI motility
Give an example of a methylxanthine drug. How is it administered? How is it excreted?
Theophylline
Oral administration
By kidneys (parent drug and metabolites)
(Also penetrates BBB)
