Chapter 2 Flashcards
Drug
Any chemical that affects the physiologic processes of a living organism
Pharmacology
Study or science of drugs
Chemical Name
Describes the drug’s chemical composition and molecular structure
Generic Name
(Non proprietary name)
Name given by the United States Adopted Name Council
Trade Name
(Proprietary Name)
The drug name has a registered trademark; use of the name is restricted by the drug’s patent owner (Usually the manufacturer)
Pharmaceutics
The study of how various drug forms influence pharmacokinetic and pharmacodynamics activities
Pharmacokinetics
The study of what the body does to the drug Absorption Distribution Metabolism Excretion
Pharmacodynamics
The study of what the drug does to the body
The mechanism of drug actions in living tissues
Pharmacotherapeutics
The use of drugs and the clinical indications for drugs to prevent and treat diseases
Pharmacognosy
The study of natural (plant and animal) drug sources
Drug absorption of various oral preparations
Fastest to slowest
Liquids, elixirs, syrups Suspension solutions Powders Capsules Tablets Coated tablets Enteric-coated tablets
Pharmacokinetics: Absorption
The rate at which a drug leaves its site of administration, and the extent to which absorption occurs
- Bioavailability
- Bioequivalency
Factors that affect absorption
Absorption characteristics vary according to the dosage form and route
- Food or fluids administered with the drug
- Dosage formulation
- Status of the absorptive surface
- Rate of blood flow to the small intestine
- Acidity of the stomach
- Status of GI motility
Routes
A drug’s route of administration affects the rate and extent of absorption of that drug
- Enteral (GI tract)
- Parenteral
- Topical
Enteral Route
The drug is absorbed into the systemic circulation through the oral or gastric mucosa or the small intestine
- Oral
- Sublingual
- Buccal
- Rectal
First-Pass Effect
The metabolism of a drug and its passage from the liver into the circulation
A drug given via the oral route may be-
Extensively metabolized by the liver before reaching the systemic circulation (high first-pass effect)
The same drug given IV-
Bypasses the liver, preventing the first-pass effect from taking place, and more drug reaches the circulation
Parenteral Route
- Intravenous (fastest delivery into the blood circulation)
- Intramuscular
- Subcutaneous
- Intradermal
- Intraarterial
- Intrathecal
- Intraarticular
Topical Route
- Skin (including transdermal patches)
- Eyes
- Ears
- Nose
- Lungs (inhalation)
- Rectum
- Vagina
Distribution
The transport of a drug in the body by the bloodstream to its site of action
- Protein binding
- Water soluble vs. fat soluble
- Blood brain barrier
- Areas of rapid distribution: heart, liver, kidneys, brain
- Areas of slow distribution: muscle, skin, fat
Metabolism/Biotransformation
The biochemical transformation of a drug into an active metabolite, a more soluble compound, or a more potent metabolite
- Liver (main organ)
- Skeletal muscle
- Kidneys
- Lungs
- Plasma
- Intestinal mucosa
Biologic transformation of a drug into:
- An inactive metabolite
- A more soluble compound
- A more potent metabolite
Factors that decrease metabolism
- Cardiovascular dysfunction
- Renal insufficiency
- Starvation
- Obstructive jaundice
- Slow acetylator
- Erythromycin or ketoconazole drug therapy
Factors that increase metabolism
- Fast acetylator
- Barbiturate therapy
- Rifampin therapy
Delaying drug metabolism causes:
- Accumulation of drugs
* Prolonged action of the drugs…drug toxicity
Stimulating drug metabolism causes:
*Diminished pharmacologic effects
Excretion
The elimination of drugs from the body
- Kidneys
- Liver
- Bowel- biliary excretion-enterohepatic recirculation
Half Life
- The time it takes for one half of the original amount of a drug to be removed from the body.
- A measure of the rate at which a drug is removed from the body
- Most drugs considered to be effectively removed after about five half-lives
- Steady State
Onset
The time it takes for the drug to elicit a therapeutic response
Peak
The time it takes for a drug to reach its maximum therapeutic response
Duration
The time a drug concentration is sufficient to elicit a therapeutic response
Peak Level
Highest blood level
Trough Level (Nadir)
Lowest blood level
Pharmacodynamics: Mechanism of Action
- Receptor interactions
- Enzyme interactions
- Nonselective interactions
Agonist
Drug binds to receptor: there is no response
Partial Agonist
Drug binds to the receptor, the response is diminished compared with that elicited by an agonist
Antagonist
Drug binds to the receptor: there is no response. Drug prevents binding of agonists
Competitive Antagonist
Drug competes with the agonist for binding to the receptor. If it binds there is no response
Noncompetitive Antagonist
Drug combines with different parts of the receptor and inactivates it: agonist then has no effect
Pharmacotherapeutics: Types of Therapies
- Acute therapy
- Maintenance therapy
- Supplemental/replacement therapy
- Palliative therapy
- Supportive therapy
- Prophylactic therapy
- Empiric therapy
Contraindications
- Any characteristic of the patient, especially a disease state, that makes the use of a given medication dangerous for the patient
- It is important to assess for contraindications
Therapeutic Index
Ratio of a drug’s toxic level to the level that provides therapeutic benefits
Tolerance
Decreasing response to repeated drug doses
Dependence
Physiologic or psychological need for a drug
Interactions may occur with other drugs or food ***A drug interaction is the alteration of a drug’s actions by:
- Other prescribed drugs
- Over-the-counter medications
- Herbal therapies
Drug Interactions
- Additive
- Synergistic
- Potentiation
- Antagonistic
- Incompatibility
Drug Sources: Four main sources
- Plants
- Animals
- Minerals
- Laboratory synthesis
