Medical Pharmacology General
Principles Practice Questions
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Description of enantiomers:
May be readily superimposed
Enantiomers, when presence in equal proportions, are referred to as racemates
May be characterized by absolute configuration or by direction in which enantiomers rotate polarized light
A & C
B & C
Characteristic(s) of enantiomers:
Chemically identical
Mirror images of each other
Both
Neither
The binding of the activated form of phenoxybenzamine (alpha-receptor antagonist) with the alpha receptor is an example of this type of chemical force/bond:
Electrostatic
Covalent
Hydrophobic interactions
Characteristics those aqueous diffusion:
Occurs within large intracellular and extracellular components
Occurs across epithelial membrane tight junctions
Occurs across endothelial blood vessel lining -- often through pores
A & C
A, B & C
Major types of chemical forces/bonds:
Hydrophobic interactions
Electrostatic
Covalent
A & C
A, B, & C
Factors that influence the rate of passive movement to molecules down the concentration gradient (Fick's Law)
Concentration difference across the barrier
Area across which diffusion occurs
Drug mobility in the diffusion panel
Thickness -- length of the diffusion pass
All the above
Saturable transport system(s):
Facilitated diffusion
Passive diffusion
ASctive transport
A & B
A & C
Stereoselectivity and metabolism:
Enzymes typically exhibit stereoselectivity
i.e. a preference for one or the other enantiomeric form
Duration of action of one enantiomer may be different from the other
both
neither
Percentage of all drugs that exist as enantiomeric pairs:
Less than 1%
5%-15%
30%
> 50%
> 90%
Examples of enantiomeric differences important in anesthesia:
Cardiotoxicity is probably associated with both enantiomers of bupivacaine
Ropivacaine is less cardiotoxic compared to bupivacaine because it is metabolized faster
Cisatracurium is an atracurium isomer that doesn't cause histamine release
