Pharmacology 1

Front 1

Solubility

Back 1

the ability to diffuse through lipid bilayers is important for most drugs. Water solubility can be used for aqueous phase drugs

Front 2

Ionization

Back 2

Only the nonionized form of a drug crosses biomembranes.

Ionized form of drugs are better for renal excretion b/c they are water soluble.

Front 3

Bioavailability (f)

Back 3

Measure of the fraction of a dose that reaches the systemic circulation.

If f=1, intravascular bioavailability is 100%

Front 4

First-Pass Effect

Back 4

As drugs are absorbed orally most of the time, the portal circulation will initially distribute them to the liver. For some drugs, their rapid hepatic metabolism decreases their bioavailability - this is what is known as the "first pass effect".

Front 5

Drug- protein complex

Back 5

This is the inactive bound to plasma proteins in circulation.

Competition between drugs for plasma pro tine-binding sites may increase the "free fraction", possibly enhancing the effects of the drug displaced/

Front 6

Barriers to distribution

Back 6

Placenta

Blood-brain- permeability (lipid soluble)

Front 7

Apparent Volume of Distribution

Back 7

the kinetic parameter of a drug that correlates dose with plasma level at zero time.

Front 8

Elimination

Back 8

concerns the process involved in the elimination of drugs from the body and their kinetic characteristics

Front 9

Zero-Order Elimination rates

Back 9

When a drug is eliminated from the body at a constant rate over a unit of time.
so like every 4 hours 10 mg of a drug is eliminated; so:
80mg --4h--> 70 mg --4h--> 60mg --4h--> 50mg...etc.

Drugs like this have no fixed half life, and their elimination is independent of plasma concentration.

These are drugs like Ethanol, phenytoin, and salicylates.

Front 10

First-Order Elimination rates

Back 10

This is when a constant fraction of a drug is eliminated per unit time. This is exponential Decay or "half-life".

The rate of elimination is directly proportional to plasma level - the higher the amount, the more rapid the elimination.

Most drugs follow this type of kinetics, where "t 1/2" is constant.