What is a Drug?
A biologically active substance that can modify cellular function.
Each drug has its own what?
Dose response curve
What are the characterizations of drugs?
- Dose-Response Curve -Potency -Efficacy
What is Potency of a drug?
A function of the amount of the drug required to produce an effect. **Drug A requires less dosage to produce the same effect as Drug B which has a higher Dosage. ** Example: 10mg of morphine produces the same effect as 100mg of meperidine, which means morphine is more potent.
What is Efficacy?
The maximum intensity of effect or response that can be produced by a drug. **The maximum response of a drug regardless of the dose.
What are the Mechanism of Action of Drugs?
-Pharmacologic Effect -Therapeutic Effect -Adverse Effect
What is Pharmacologic Effect?
-Produces the same action as endogenous agent. -Block action of endogenous agent.
What is the Agonist?
-Has affinity for a receptor -Combines with the receptor -Produces an effect. -It encourages the drug to work.
What is an Antagonist?
Counteracts the action of the agonist. -Stops the work of the drug.
What is Pharmacokinetics?
The study of how a drug enters the body, circulates within the body, is changed by the body, and leaves the body.
What are the 4 major steps of pharmacokinetics?
ADME 1. Absorption 2. Distribution 3. Metabolism 4. Excertion
What is Absorption?
The transfer of the drug from the site of administration tothe blood stream.
What are the mechanisms of drug transfer during drug absorption?
-Passive Transfer -Simple diffusion
What is the Specialized transport during drug absorption?
-Active Transport -Facilitated Diffusion
If the drug is non-ionized it is what?
Lipid soluble and passed through the membrane easier.
If the drug is more ionized it is what?
Less Lipid Soluble and has a more difficult time passing through the membrane.
Lipid soluble drugs move across most biological membranes by what?
Which type of drug administration bypass the absorption step?
What organ is the most important for absorption of drug?
The small Intestines
What is distribution?
The process by which a drug leaves the blood stream and enters the body system.
Sublingual doses are distributed to what organ?
Drugs are distributed to organs with what?
Higher blood flow
Drugs may be bound to what?
Proteins in the blood especially plasma Albumin
What is metabolism/biotransformation?
the body's way of changing a drug so that it can be more easily excreted by the kidneys.
What does Prodrug mean?
What does the metabolism mechanism Active to Inactive mean?
The drug is active when it is put into the mouth but then the liver will turn the drug inactive once it breaks it down.
What does the metabolism mechanism Inactive to Active mean?
The drug is inactive when put into mouth but then once the liver breaks it down it starts to be active.
What does the metabolism mechanism Active to Active mean?
It is active when taken and active when broken down.
Which Metabolism Mechanism can be more potent?
Active to Active
The ________ is the more important site for the metabolism of drugs.
What is another name for Metabolism?
Rate and efficiency is dependent upon what?
The route of administration.
What is Elimination?
The removal of the drug from the body.
What does elimination of the drug do?
Termination of the drug Effect
What is the most important organ during elimination?
Kidneys (renal Excretion)
What are other routes of elimination?
What are the three routes of elimination in the kidneys?
-Active Tubular Secretion
-Passive Tubular diffusion
What are the factors that influence rate of drug absorption?
-Site of Absorption
-Solubility of drug
What are the factors that affect drug absorption and clinical pharmakinetics?
-Presence of Infection
-Dose Form: Pill Form vs. Liquid
-Drug Solubility: Fat Soluble vs. Water Soluble
-Blood flow at injection Site
What are the factors that determine distribution of a drug?
-Blood flow to organ
-Plasma Protein-binding capacity
-Presence of Barriers
What factors affect drug metabolism?
-Impaired liver function
-herpatic liver circulation
-Drugs and environmental substances
-Inhibitors of Cytochrome P450
The Cytochrome P450 Isoenzyme Inhibitors do what?
Inhibit the liver from breaking down the substrate which means there will be too much substrate.
The Cytochrome P450 Isoenzyme Inducers do what?
Cause the the drug to be more quickly metabolized which makes there not be enough of the substrate.
What is Drug Half-Life?
The time it takes for the concentration of a drug to fall to one-half (50%) of its original blood level.
What are Altering Drug Effects?
-Time of Administration
- Route of Administration
-Age and Weight
What is Onset?
Time it takes for the drug to begin to have its effect.
What is Duration?
The length of time of a drug's effect.
What are the two routes of Administration dose forms?
What is Enteral Route?
Mouth and rectum route
What is Parenteral Route?
Injection, Inhalation, Topical
What are the advantages oral route?
-Small intestines presents large absorbing area
-Produces slower onset of action
-Safest, least expensive and most convenient.
What are the disadvantages of oral route?
-Certain drugs are inactivated by GI tract acidity or enzymes.
-Requires pt. Cooperation
-Less predictable drug level of drug
WHat are the advantages of Rectal Route?
-Used if pt. is vomiting or unconcious
-Produces local or systemic effect
What are the Disadvantages of Rectal Route?
-Drugs are poorly and irregularly absorbed
-Poor Pt. Acceptance
What are the Advantages of IV Route?
-Produces most rapid drug response
-Produces predictable response
-Use in emergency situations
-Absorption stage is bypassed (bypass stomach)
What are the disadvantages of IV route?
-Phlebitis (inflammation of vein)
-Side Effects related to high plasma concentration
What are the advantages of Inremuscular Route?
-Allows increased tolerance to irritating drugs
-Allows injection of suspensions, which provides a sustained effect
-Massaging the muscle will increase the drugs absorption.
-Deltoid or Gluteal muscles are common injection sites.
What is subcutaneous route?
Injection of drugs into subcutaneous areolar tissue.
What are the advantages of Subcutaneous Route?
-Used to administer protein products.
-Insulin is administered this route.
What are the disadvantages of subcutaneous Route?
Irritating solutions may cause sterile abscesses
TB SKin Test
Into spinal Subarachnoid space
-Used in pt. with renal failure.
What are the advantages of inhalation route?
-Rapid Onset of action due to large surface area of respiratory mucosa.
-Lack of need for needles.
What are the disadvantages of Inhalation Route?
Popular route for abuse of drugs
What are the advantages of Topical Route?
Systemic side effects are rare.
What are the disadvantages of Topical Route?
-Increased risk of systemic side effects if surfaces are large and/or abraded, Inflamed, or Sloughing
-Intraorally spayed anesthetics may be absorbed into the blood stream.
-Requires an increased concentration of the drug.
Parenteral Route (IV, IM, SQ, Intradermal) do what?
Bypass the GI Tract