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29 Cards in this Set

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What is the definition of pharmacology?
The study of substances that interact with living systems through chemical processes by binding to regulatory molecules and activating or inhibiting normal body processes.
Describe the difference between medical pharmacology and toxicology.
Medical pharmacology is the administration of chemical substances to acheive beneficial response. toxicology is the branch of pharmacology that deals with undesirable effects of chmicals.
How do we evaluate therapeutic claims of drugs now?
By way of controlled clinical trials.
To interact chemically with receptors, drugs must be (4 things):
1. appropriate size
2. appropriate electrical charge
3. appropriate shape
4. appropriate atomic composition.
At room temperature, durgs may have what physical properties?
solid
liquid
gas

May be weak acids or bases
What might affect the degree of ionization of a drug?
The pH differences in various body compartments will alter the degree of ionization.
What determines diffusion between body compartments?
molecular weight.
What is the range of molecular weights?
from MW of 7 (lithium)
to Mw 59,050 (t-PA)
What is the MW of most drugs?
Usually the MW is between 100 and 1000.
What happens if the MW is over 1000?
Mw over 1000 will not diffuse easily. Large drugs must be administered directly into the compartment where they have their effect.
Drug Receptor Bonds: Give, in order, the strongest to weakest bonds
covalent to
ionic to
hydrogen to
hydrophobic to
van der Waals
Describe covalent bonding
Covalent bonds are formed by the sharing of a pair of electrons.
It is very strong, not usually reversible.
You may see a termination of action only after formation of new receptors
Describe Ionic bonding (aka electrostatic)
They are weaker and more common than covalent.

Acidic or basic drugs that are ionized at plasma pH easily combine with charged groups on receptors

Reaction reversed by change in pH
To summarize, in a covalent bond there is a ____ of electrons.
In an ionic bond , there is a ____ of electrons.
In covalent bonds, there is a sharing of electrons. In ionic bonds there is a sharing of electrons
Describe hydrogen bonds
Hydrogen forms polar covalent bonds to more electronegative atoms such as oxygen.

Unique properties of water are largely due to strong hydrogen bonding that occurs between it's molecules.

Molecule providing a polar hydrogen for a hydrogen bond is called a DONOR

Molecule providing electron rich site that attracts hydrogen is called an ACCEPTOR
Describe hydrophobic bonding
Hydrophobic bonding is usually weak - probably important in interaction of highly lipid-soluble drug with lipids of cell membranes and internal wall of receptor

Formed between hydroxyl or amino group and negative carboxyl groups
What is the Van der Waals force?
It's a chemical bond (drug-receptor bond). IT is a weak bond between atoms of different molecules.
are drugs that form weak bonds usually more or less selective than those that form strong bonds?
Drugs that form weak bonds require precise fit to a receptor. Only a few receptors are likely to fit.

Highly selective, short acting drugs form weak bonds compared to less selective long acting (covalent) bonds.
What does drug shape matter in bonding?
The shape of the drug must allow bonding to the receptor site. It optimally fits like a key.
What is chirality?
Chirality is a complex definition for a very simple idea. Basically, molecules can have teh same structural formula, but their atoms are arranged in a different order (just like your fingers and thumbs).
Describe the sterioisomerism of chirality
Molecules are 3D

carbon atom bonded to 4 different groups of atoms is called a stereogenic center

Chiral molecules rotate around that center

By definition a chiral molecule is one that cannot be superimposed onto its mirror image.
Using your hands, describe chirality
Your hands possess chirality. You cannot superimpose one hand on the other yet they are a mirror image of each other.
In chirality, groups are oriented around a carbon atom in 2 ways. What are the 2 ways?
Dextro
and
Levo
What is dextro?
dextro: if the direction is rotated in clockwise direction, the molecule is designated as R (right) or dextro
What is levo?
if the direction is rotated counterclockwise, the molecule is designated as S
Why is chirality important?
It is important in the synthesis of drugs. Manipulation of rotation or formation of levo or dextro isomers allow new drugs to cause the desired effect with fewer side effects.
Chirality is the basis for entantiomerism. Describe enantiomers and racemix mixtures
Enantiomers are substances that are mirror images of each other but cannot be superimposed.

Racemic mixtures have 2 enantiomers in equal proportions. One enantiomer in racemic mixture causes effect and other may case side effects
drug shape/chirality....what about it?
The drug shape may contain the same components but different shapes so these drugs may have different side effects. Same main action but maybe less side effects
What is rational drug design?
Molecular structure developed based on biologic receptor known as rational drug design.
Design based on 3D structure of the receptor site