4 Components of

Pharmacokinetics

1. Absorbtion
2. Distribution
3. Metabolism
4. Elimination

A.D.M.E.

Continuous-Rate Infusion

(C.R.I.)

1. Intracardiac-only in emergencies (painful)
2. Intratracheal-only in emergencies(when a vein is not available rapidly)

Passive Diffusion:

Definition & General Facts

1. Random movement of molecules from an area of high concentration to an area of low concentration
2. Requires no energy
3. Comprises the majority of drug movement through tissue, fluid, & membrane barriers

2 mechanisms by which drugs cross membranes via passive diffusion?

1. Oral meds given, absorbed in small intestine to blood, then flows through Hepatic Portal vein to liver.
2. Liver metabolizes drug and amount of time it takes to do so determines high (rapid metabolism, where body hardly gets any) or low(slow metabolism, where it stays in the body longer, has more effect).

Facilitated Diffusion:

Require energy? How does it work and what influences it?

1. No ATP required
2. Uses Carrier (protein)Molecules to pass through cell membrane (revolving door) using concentration gradient, which continues after equalibrium is reached.
3. Influenced by temperature, membrane thickness, size of molecules,& whether drug is lipo-/hydro-philic

Active Transport:

How does it work?

Is energy required?

1. Carrier molecules within the membrane move the drug using ATP to reset it after transport.
2. Can move against concentration gradient (Na/K pump)
3. Not a common way to absorb drugs
4. Requires time...(t max)

1. The maximum speed at which a transport molecule can work...(may limit movement/result in backlog)
2. Only applies to Facilitated & Active transport.

Gain or lose hydrogen ions as a result of environmental pH?

1. Acidic drugs     2. Alkaline drugs

1. Acidic drugs lose hydrogen ions
2. Alkaline drugs gain hydrogen ions

Which ionizes (becomes charged) in an acidic environment, an acidic drug or an alkaline drug?

Alkaline gains a hydrogen and becomes positively charged.

ionized molecules are:

lipophilic/hydrophilic?

Will ionized (charged) molecules be able to dissolve in cell membranes?

Orally-administered drug is absorbed in the small intestine, into the blood, which flows directly through the hepatic portal vein and onto the liver to be metabolized.

(high F.P.E.=limited drug effectiveness)

1. Fenestrations  (tiny holes between cells that allow small molecules to pass between, rather than through them)
2. Tight (only way to cross this is to dissolve into it-lipophillic. ex.blood/brain barrier)

Distribution: drug advancing from systemic circulation to tissues.

Redistribution: drug moving back from tissues into systemic circulation.

1. Renal disease
2. Liver disease
3. Intestinal loss

1. How the body changes the drug given.
2. Liver (hepatic biotransformation)
3. Molecules become hydrophilic
4. Chemical conversion of the drug, then eliminated (urinated/defecated)

Induced Biotransformation

1. Feces/Unine
2. Hydrophilic

1. Kidney
2. Liver
3. Lungs
4. Skin