For midterm- PD&PK Flashcards
Racemic mixture
50:50 mixture of both enantiomers
True or false: Local anesthetics bind to voltage activated (gated) sodium (Na+) channels to shorten the refractory period
False
Which form of transfer of drugs across membranes dominates for most drugs
A. Active transport
B.Paracellular transport
C. Facilitated transport
D.Passive diffusion
Passive diffusion
Decreased clearance of a drug could ______ the elimination half life
Decreased distribution of a drug could _____ the elimination half life
decrease
Secondary structure results from
Protein a.a interacting with other nearby a.a’s on same protein
Tertiary structure results from
Interaction of more distant a.a’s along a.a
Quaternary structure
Multiple polypeptides interact
Order of bond strength
Covalent > ionic > hydrogen > van der waals
Enantiomers
S: left handed
R: right randed
(based on organization around chiral centre)
Racemic mixture
50:50 mix of both enantiomers
Ranitidine: what is it and what is interesting about it
H2 (histamine receptor) antagonist or blocker
* Reduce Hcl production
* Limited effects in body due to restriction of H2 receptors in the
stomach
Nicotinic acetylcholine receptor: what type of channel, how does it open and where is it found?
Ligand-gated channel
Most important receptor type for drugs
Proteins
Ion channels have key role in
-neurotransmission
-sm. & sk. muscle contraction
-cardiac contraction
-secretion
Excitatory NTs
ACh or glutamate
Inhibitory NTs
Glycine or GABA
What binds to channel to prolong refractory period
Local anesthetics
G-protein activated by
NTs, eicosanoids, peptides, opioids
G-proteins work where
Over 50% - sensory perception
Remainder - nerve regulation, sm muscle tension, force/rate of cardiac contraction, secretion
Major role of G proteins
Activate effector molecules, produce second messengers
Hormones of a tyrosine-kinase associated receptor
Growth hormone, prolactin
Nuclear hormone receptor (intracell.)
Circulating steroid hormone (lipophilic) –> diffuse thru PM –> bind TF –> modify nuclear events
NO affect on cGMP
NO binds N-term coluble cGMP –> enhance cGMP amp
2 major types of D-R relationships
Graded: D-R of an individual
Quantal: D-R of a population of individuals
Fraction of all available receptors that are ligand bound
[LR]/Ro
Affinity of a drug is most influenced by changes in the _______ rate
Off
Efficacy (Emax)
Maximal response produced by the drug at that receptor
Potency (EC50)
Drug concentration which elicits 50% of the maximal response
(Emax); function of affinity and efficacy
Therapeutic index (TD50/ED50)
Estimate of relative safety margin of drug
More potent drugs have a ______ affinity (______ Kd ) for their receptors
Greater affinity, lower Kd
More efficacious drugs (larger Emax ) usually cause a _________ proportion of their receptors to be activated
Greater
Partial agonist
Not able to achieve the same maximal response at a given receptor compared to a full agonist; even with increasing [agonist] BUT MAY SHOW GREATER POTENCY
Types of receptor agonists
Reversible (competitive)
Irreversible (non-competitive)
Nonreceptor antagonists
Chemical antagonist
Physiologic antagonist
Increase in Kd does what to potency
Decrease
What do noncompetitive antagonists do
Depress the maximal response or efficacy (Emax ), can also decrease potency
