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RT Pharmacology Ch 2
Principles of Drug Action
Question | Answer |
---|---|
The primary site of drug metabolism & excretion is the? | Kidney |
Routes of drug administration: | -Enteral -Parenteral -Inhalation -Transdermal -Topical |
Enteral routes of administration: | Most common rout is by mouth (oral) -Tablet -Capsule -Elixir -Suspension |
Parenteral routes of administration: | -Intravenous IV -Intramuscular IM -Subcutaneous SC -Intrathecal IT -Intraosseous IO *Solution *Suspension *Sub-lingual *Suppository *Depot (bypass first-pass & GI) |
Transdermal routes of administration: | -Patch -Paste |
Inhalation routes of administration | -Aerosol -Gas *for either systemic or local effect |
Topical routes of administration | -Powder -Lotion -Ointment -Solution -Eye drops -Nasal spray |
Agonist | Chemical or drug that binds to a receptor and creates an effect on the body. |
Antagonist | Chemical or drug that binds to a receptor bud does not create an effect on the body; it blocks the receptor site from accepting an agonist. |
Bioavailability | Amount of drug that reaches the systemic circulation. |
Drug Administration | Method by which a drug is made available to the body. |
First-pass Effect | Initial metabolism in the liver of a drug taken orally before the drug reaches the systemic circulation. *High first-pass effect = Low systemic side effect |
Hypersensitivity | Allergic or immune-mediated reaction to a drug, which can be serious, requiring airway maintenance or ventilatory assistance. |
Idiosyncratic Effect | Abnormal or unexpected reaction to a drug, other than an allergic reaction, as compared with the predicted effect. |
Lung Availability/Total Systemic Availability Ratio (L/T ratio) | Amount of drug that is made available to the lung out of the total available to the body. *Tells you how effective inhalation of medication will be and the amount of systemic side effects *L/T ration should be as close to 1 as possible |
Pharmacodynamics | Mechanisms of drug action by which a drug molecule causes its effect in the body. *What the medication does to the body |
Pharmacokinetics | Time course and disposition of a drug in the body, based on its absorption, distribution, metabolism, and elimination. *What the body does to the medication |
Receptor | Cell component that combines with a drug to change or enhance the function of the cell. |
Structure-activity relationship (SAR) | Relationship between a drug's chemical structure and the outcome it has on the body. |
Synergism | Drug interaction that occurs from two or more drug effects that are greater than if the drugs were given alone. *1+1=3 *Sleeping Pill/Sedative + Alcohol |
Additivity | Occurs when two drugs act on the same receptors, and the combined effect is the simple linear sum of the effects of the two drugs, up to a maximal effect. 1+1+2 *Anticoagulant+Alcohol |
Potentiation | A special case of synergism in which one drug has no effect but can increase the activity of the other drug. *1+0=2 |
Tachyphylaxis | Rapid decrease in response to a drug. |
Therapeutic Index (TI) | Difference between the minimal therapeutic and toxic concentrations of a drug; the small the difference, the greater change the drug will be toxic. *Ratio between LD50 & ED50 *Narrow = Dangerous *Wide = Less Dangerous |
Tolerance | Decreasing intensity of response to a drug over time. |
Absorption/Mechanisms by which drugs move across membrane barriers: | -Aqueous diffusion -Lipid diffusion -Carrier-mediator transport -Pinocytosis |
Mucosoal barrier consists of: | -AW surface liquid -Epithelial cells -Basement membrane -Interstitium -Capillary vascular network |
Bioavailability is influenced by: | -Absorption -Inactivation by stomach acids -Metabolic degradation -Blood flow to site of absorption |
Primary site of drug metabolism and biotransformation: | Liver |
Drug Distribution | The process by which a drug is transported to its sites of action, eliminated, or stored. |
Volumes of major body compartments: | Vascular - 5L Interstitial Fluid - 10L Intracellular Fluid - 20L Fat - 14-25L |
Clearance | A measure of the ability of the body to rid itself of a drug *AKA Total systemic or plasma clearance |
Plasma Clearance (CLp) | Hypothetical volume of plasma that is completely cleared of all drug over a given period. *L/hr or L/hr/kg |
Factors increasing L/T ratio: | -Efficient deliver devices -Inhaled drugs with high first-pass metabolism -Mouth washing, including rinsing and spitting -Use of a reservoir device |
Chemical Antagonism | Direct chemical interaction between drug and biologic mediator, which inactivates the drug. |
Functional Antagonism | Can occur when two drugs each produce an effect, and the two effects cancel each other. |
Competitive Antagonism | Occurs when a drug has affinity for a receptor but no efficacy and at the same time blocks the active agonist from binding to and stimulating the receptor. |
Maintenance Dose | Rate at which medication must be replaced to maintain steady plasma levels. *Calculated dose and schedule *Small doses must be given more frequently |
Time-Plasma Curve | Concentration of the drug in plasma over time; helps to determine the choice of medication for a clinical situation, and a dosing schedule. |
Plasma Half-Life | Amount of time the body takes to completely metabolize and eliminate 50% of the dose *1:50%, 2:25%, 3:12.5%, 4:6.25%, 5:3.12%, 6:1.56%, 7:0.78%, 8:0.39%, 9:0.19% |
EC50 or ED50 | Effective concentration or dose of a medication that produces 50% of the drugs maximal response. |
The most common route of drug distribution: | The Circulatory System |
Which of the following is the most dangerous TI number: 2, 37, 25 | 2 (narrow) |
The most common route of medication administration to the general out patient population is? | Oral |
Which of the four major body compartments contains the smallest volume in liters? | Vascular 5L |
What is the most important liver enzyme? | Cytochrome P450 |
What is the relationship from chemical activity to its clinical activity? | Structure Activity Relationship (SAR) |
The most significant documented contraindication do medication delivery is? | Hypersensitivity |