Pharm chapter 2 Flashcards
What is the study of the interactions between the chemical components of living systems and the foreign chemicals, including drugs, that enter living organisms; the way a drug affects a body?
pharmacodynamics
What are the four ways drugs work within the body?
- replace or act as a substitute for missing chemicals
- to increase or stimulate certain cellular activities
- to depress or slow cellular activities
- to interfere with the functioning for foreign cells
What involves the study of absorption, distribution, metabolism, and excretion of drugs?
pharmacokinetics
What is the clinical practice considerations of pharmacokinetics?
- the onset of drug action
- drug half-life
- timing of the peak effect
- duration of drug effects
- metabolism of the drug
- site of excretion
The amount of a drug that is needed to cause a therapeutic effect is called?
critical concentration
The actual concentration that a drug reaches in the body results from a DYNAMIC EQUILIBRIUM involving several processes which are?
- absorption from the site of entry
- distribution to the active site
- Metabolism in the liver
- Excretion from the body
The processes 0f dynamic equilibrium are key elements in?
- determining the amount of drug dose
- the frequency of dose repetition
What is the absorption of the oral route?
- the acidic environment of the stomach is the first barrier to the foreign chemical (the drug)
- the acid breaks down many compounds and inactivates others.
- the binders that are used often are designed to break down in a certain acidity and release the active drug to be absorbed.
What is the absorption of the IV route?
- reach there full strength at the time of injection, avoiding the initial breakdown.
- immediate onset, fully absorbed at administration because they are directly entered through the blood stream.
What is the absorption of the IM route?
- absorbed directly into the capillaries in the muscle and sent into circulation.
- takes time because the drug must be picked up by the capillary and taken into the veins.
What is the absorption of the subcutaneous injections route?
- deposits the drug just under the skin, where it is slowly absorbed into circulation.
- timing of absorption varies, depending on the fat content of the injection site and state of local circulation.
Factors that affect absorption of IV drugs are?
Nothing
Factors that affect absorption of intramuscular (IM) drugs are?
- perfusion of blood flow to the muscle.
- fat content of the muscle
- temperature of the muscle: cold causes vasoconstriction and decreases absorption; heat causes vasodilation and increases absorption.
Factors that affect absorption of subcutaneous drugs are?
- perfusion of blood flow to the tissue.
- fat content of the tissue
- temperature of the tissue: cold causes vasoconstriction and decreases absorption; heat causes vasodilation and increases absorption.
Factors that affect absorption of PO (oral) drugs are?
- acidity of stomach
- length of time in stomach
- blood flow to gastrointestinal tract
- presence of interacting foods or drugs