Lec 6

deals with the drug disposition; “what the body does to the drug”

bodily processes involved in drug disposition which influence drug levels in the body

routes of drug administration

route of DA that initiate orally or rectally

non-oral routes

passage of drug molecules from the site of administration into the blood circulation

types of drug effect

effect that occurs when a drug is absorbed into the blood circulation

effect that is not preceded by absorption

usual site of absorption for orally administered medications

T or F.

Absorption may begin in the mouth and stomach for some drugs

rate-limiting factor in absorption from the gut

rate-limiting factor in absorption from IV injections

rate-limiting factor in absorption from all other routes

T or F.

The sublingual route is both enteral and parenteral.

it is the most important mechanism for passage of drugs; it requires the establishment of a concentration gradient across the membrane

characteristics of a drug in order for it to move through the cell membrane by passive diffusion

T or F.

Aside from passive diffusion, a drug can also be transported across cell membrane via carrier mediated transport and pinocytosis.

a measure of how much drug is absorbed into the blood circulation; expressed as percent of the dose administered

If 100 mg of a drug is administered orally and only 50 mg of the drug is absorbed unchanged, the bioavailability is:

minimum level of a drug that should be attained in the plasma in order to induce an effect

T or F.

There is still slight pharmacological effect produced below MEC.

factors affecting GIT absorption

pharmaceutical factors that affect the dissolution of dosage forms

process of reducing particle size to improve the rate of drug dissolution, thus resulting in greater GIT absorption of the drug

arrange the following dosage forms based on their availability to be absorbed:

suspension, tablet, capsule, solution

Answer this way:

suspension > tablet > capsule > solution

physiologic factors that affect the transit time of drug along the GIT

T or F.

Ruminants have more alkaline pH in the GIT while carnivores have more acdic pH in the GIT

physicochemical factors affecting the absorption of drugs in the GIT

ration of drug solubility in oil to its solubility in water; reflects the lipid solubility of a drug

T or F.

high oil/water partition coefficient means that the drug is less lipid soluble, and thus has lower absorbability

T or F.

A drug tends to pass thru the membrane if it is uncharged.

T or F.

Uncharged drugs are less lipid-soluble than charged drugs.

T or F.

The degree of ionization of a drug is related to its acidic or basic properties.

T or F.

Drugs are mostly weak acids or weak bases.

factors affecting the degree of ionization

T or F.

When a weak acid reacts in an acidic environment, it becomes lipophilic which is more absorbable in the body.

T or F.

When a weak base reacts in an acidic environment, it transforms into a lipophilic form.

Weak bases are best absorbed from the ___

They are best absorbed from the stomach

T or F.

The lower the pK, the stronger the weak acid.

T or F.

The higher the pK, the stronger the weak acid.

demonstrates the effect of drug pH, drug pKa, and the pH of the medium on the degree of drug ionization

Henderson-Hasselbach equation