Untitled Quiz

Study Notes

Focuses on how the body influences drug liberation and absorption.
LADMER: liberation, absorption, distribution, metabolism, excretion, and response.
Key factors affecting absorption: drug's physico-chemical properties, solubility, pKa, Log P, molecular weight, dissolution rate.

US-FDA definition: The rate and extent to which an active drug is absorbed and becomes available at the site of action.
Measured by: rate of absorption (ka), elimination rate (k), time to maximum concentration (tmax), maximum concentration (Cmax), area under the curve (AUC).
Intravenous (i.v.) administration has 100% bioavailability.
Non-i.v. administration has a bioavailability ranging from 0 to 100% due to factors like degradation in the stomach or liver metabolism.

Compares bioavailability between different products of the same drug and dose.
Focuses on rate and extent of absorption, aiming for 80-120% of the standard or innovator product.
Bioequivalence may be intentional, meaning that different products may have equivalent absorption extent but different absorption rates.

Primarily influenced by the drug's dissolution rate and permeability.
Key concept: Only soluble, unionized, and moderately non-polar compounds can easily absorb.
Mechanism:
- Passive transport: through cells (transcellular) or between cells (paracellular).
- Carrier-mediated transport: facilitated (e.g., cephalosporins, vitamin B12) or active (e.g., 5-fluorouracil).
- Vesicular transport: for particulates and macromolecules.
- Drug efflux pumps: like p-glycoprotein actively pump drugs out of cells.

Composed of phospholipids (amphipathic molecules with both polar and non-polar groups).
Non-polar groups of phospholipids face inward, while polar groups face outward, creating a membrane barrier.

Driven by Fick's Law: dM/dt = DSK (Cd-Cr) / h, where D is diffusion coefficient, S is surface area, K is partition coefficient, Cd is concentration in the donor compartment, Cr is concentration in the recipient compartment, and h is membrane thickness.
Driving force: concentration gradient.
Mostly applies to lipid-soluble drugs, as they can permeate the phospholipid membrane.

Describes the movement of drugs from the bloodstream to various tissues and organs.
Influenced by: drug's physico-chemical properties, protein binding, tissue permeability, and blood flow.

The process by which drugs are removed from the body.
Includes:
- Metabolism: biotransformation reactions in the liver.
- Excretion: removal of unchanged drug or its metabolites through urine, feces, bile, or lungs.
Influenced by: drug's physico-chemical properties, enzyme activity, renal function, and other factors.