principles of Pharmacology

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principles of Pharmacology

Pharmacodynamics (Ph.Dy)

Receptor activation

Toxicity

Efficacy

Dose Response

Pharmacokientics (Ph.Ki)

Bioavailability

What affects it?

First Pass affect

absorption affects

Caculated

The equation (Not required)

Fraction of the administered drug that reaches the site of action with its unchanged from

Excretion

Metabolism

Distribution

Measurement

Importance of plasma protein

VD big= drug will distribute to other compartments= High risk and toxicity

VD small= High [plasma]= High risk and toxicity

VD = Bioavailability/ [plasma] at time= 0 sec. (L/KG)

How to determine distribution

Permeation peinciples

Where the drug distribute determination

Capillary permeability

Brain Capillary

Liver

BBB

Binding to plasma protein

Role of Plasma protein

high affinity drugs are better than low affinity when binding proteins

protein are variables in binding

When binding, drug deactivated

sequester drugs in a non diffusible form in the plasma

Degree of hydrophobity/lipidophilly of the drug.

Blood flow to a given site

Where to distribute? (In three compartments)

Tissue

Bone, Fat

Total body water

Extracellular fluids

Plasma

Drugs disseminate differently

The distribution of a drug from blood stream to interstitum or cell's tissue

Absorption

Dependence

It depends on

Effect of pH

Permeation Principles

Endocytosis/Exocytosis

Endo and Exo cytosis are almost working like Carrier mechanisms.

Special carrier mechanisms

Saturable process

Why?

Can go againts the [ ]

Can uses ATP (Active diffusion)

Lipid Diffusion

Henderson Hasselbalch law

Weak acids in Stomach. Weak bases in intestines

You can calculate charged and uncharged molc. at any given pH

Meaning you can calculate how much is absorbed

Uncharged drugs are absorped readily

Electrostaticity of lipid drugs attract water to be water soluable

Drugs migh be weak acids or bases.

Aqueous (Passive) Diffusion

Lipid-soluable drugs pass through membrane

Doesn't matter (size, charge)

Water-soluable drugs penetrate the cell membrane throuh aquoues channels

Increase size of drug, decrease absorption

Drugs move from high to low concentration

Disease state

Presence of other meds in the stomach

a drug might bind to another drug to prevent absorption

compete or carier metabolism

Presence of food (to dely)

Blood Supply

Transfer drugs from site of admin. to the site of circulation

Administration