pharma chap 2

pharmacokinetics

-process of drug movement

-how a drug travels through the body to achieve its intended action

Absorption, Distribution, Metabolism, Excretion

4 primary process encompassing Pharmacokinetics

ADME

each stage is critical in determining the drug’s onset, intensity, and duration of effect within the patient

Enteral and oral delivery

Parenteral and injection methods

Topical and inhalation techniques

Alternative non-enteral routes

Routes of administration

Topical

acts directly at the intended site, minimizing

systemic side effects by avoiding high blood concentrations.

inhalation techniques

utilizes aerosol sprays or powders to disperse medication into the airways

for rapid localized or systemic effect.

Passive diffusion

This process involves the movement of drug particles from an area of high concentration to an area of low concentration across a membrane. It occurs naturally without the requirement of cellular energy

Facilitated diffusion

Utilizing specific carrier proteins, this mechanism transports drugs from high to low concentration gradients. While it relies on specialized proteins for passage, it remains a passive process that does not consume energy

Pinocytosis

In this unique transport process, the cell membrane

engulfs drug particles to form a vesicle. This allows the cell

to internalize larger molecules or fluid droplets, effectively

moving them across the cellular barrier

Pinocytosis

In this unique transport process, the cell membrane

engulfs drug particles to form a vesicle. This allows the cell

to internalize larger molecules or fluid droplets, effectively

moving them across the cellular barrier

Intravenous (IV) administration

allows drugs to reach full strength immediately by avoiding initial breakdown

Intramuscular (IM) injections

move directly into muscle capillaries

subcutaneous (SC) injections

deposit medication under the skin for slower

systemic circulation

Mechanism of first-pass metabolism

The liver may metabolize or inactivate a portion of the drug before it reaches systemic circulation, significantly reducing the amount of active drug available.

Mechanism of first-pass metabolism

The liver may metabolize or inactivate a portion of the drug before it reaches systemic circulation, significantly reducing the amount of active drug available.

lidocaine and nitroglycerin

are not administered orally due to extensive inactivation during their initial pass through the liver

Bioavailability

represents the percentage of an administered drug that reaches systemic circulation in an active form.

half-life

This parameter represents the time required for the drug

concentration in the body to decrease by 50%. It is a critical

determinant for establishing dosing intervals and predicting

how long a medication will remain systemic.

96.9% of the drug

deemed inactive after 5 half lives

phenytoin

has a long half life, A larger initial dose is administered to rapidly achieve therapeutic drug levels, bypassing the several days typically required to reach a steady state.