Basic Pharmacology Deck 2 Flashcards
What is the volume of distribution?
Dose / initial concentration (it is the apparent volume for a given drug)
What is the clearance rate?
elimination rate constant * volume of distribution.
How do you find the serum concentration after a single iv dose of medication at a given time t?
Exponential decline given by:
Ct = Co*e^-kt
where k is the elimination rate constant.
How does one calculate the steady state concentration of a constant iv infusion?
steady state is the administration rate divided by the clearance rate.
How do you calculate the appropriate loading dose to reach a given concentration?
D-loading = steady-state concentration * volume of distribution. (divide by bioavailability of giving PO)
What is the total body storage (TBS) of a drug?
1.44 * amount administered per elimination half-life.
What is bathanechol and what does it do?
AcCh Muscarinic agonist (AcCh derivative). (parasympathomimetic), stimulates GI tract and bladder. Relatively specific for M3 receptor subtype, so little effect on heart. Resistant to all cholinesterases.
What is muscarine and what does it do?
AcCh muscarinic receptor agonist (hence name of receptor). Found in poisonous mushrooms. Not used clinically.
What is pilocarpine and what does it do?
AcCh muscarinic agonist (parasympathomimetic). Naturally occuring alkaloid, used to treat dry mouth (xerostomia) and intraocular pressure in glaucoma. Increases saliva production and facilitates resorption of aqueous humor.
What is nicotine and what does it do?
AcCh nicotinic agonist, acts at sympathetic and parasympathetic ganglia, skeletal muscles, CNS. Causes release of epi from adrenal medulla and resultant CV effects.
What is physostigmine and what does it do?
AcCh agonist, binds AcCHesterase, preventing degredation of AcCh in synaptic cleft. Physostigmine is taken up in gut more readily than neostigmine because it doesn’t have a positive charge.
What is neostigmine and what does it do?
AcCh agonist, binds AcCHesterase, preventing degredation of AcCh in synaptic cleft. Known as a reversible carbonate. Used for atony of GI tract and bladder (same as pilocarpine).
What is atropine and what does it do?
muscarinic antagonist, (parasympatholytic) autonomic effects appear in following pattern as dose increases:
1) decreased salivation and sweating
2) pupil dilation
3) decreased gut motility
4) inhibition of gastric secretion.
Little or no central effect in clinical doses.
What is scopolamine and what does it do?
muscarinic antagonist (parasympatholytic). causes drowsiness, amnesia in clinical doses. Delivered via transdermal patch to prevent motion sickness.
What is hexamethonium and what does it do?
Nicotinic antagonist, binds only to ganglia nicotinic receptor subtype (doesn’t effect nicotinic skeletal muscle receptor).
What is the baroreflex?
neurons in the aortic arch and carotid sinus sense drops in BP and change output of autonomic system. Eg. if BP drops, it will increase cardiac output and peripheral resistance. Often involves compensatory effect after drug delivery.
Which type of cholinergic receptors display biphasic effects?
Nicotinic receptors (not muscarinic).
What important hormone can be released when a nicotinic agonist is introduced?
epi and norepi, since AcCh stimulates adrenal medulla.
What is Benzotropine and what does it do?
Muscarinic blocking drug used to treat Parkinson’s disease. Loss of dopinergic neurons in brain causes hyperactivity of some cholinergic neurons, which release choline onto muscarinic receptors.
What is the primary role of alpha-adrenergic receptors?
sympathetic innervation, excitatory effects on smooth muscle, e.g. contriction of vascular beds and vasodilation.
What is the primary role of beta-adrenergic receptors?
sympathetic innervation, decreased GI motility, dilated bronchial musculature, vasodilation of skeletal muscle beds, cardiac excitatory effects.. metabolic effects.
What are the primary means by which catecholamines are broken down and how to derivatives avoid this fate?
catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). COMT metabolism can be avoided by moving or removing the hydroxyl groups at the 3 or 4 position. MAO metabolism can be avoided by methylation of side chain alpha carbon.
What is most effective route of epinephrine administration?
itramuscular or subcutaneous (IV in emergency). Epi given orally is broken down by COMT and MAO.
What is phenylephrine and what does it do?
alpha1 adrenergic receptor agonist. Used for nasal decongestion and hypotension (alpha1 constricts blood vessels in nasal mucosa, so less leaking, constricts other blood vessels so BP goes up).
