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Toxicology & TDM
Pharmcokinetics
Question | Answer |
---|---|
Pharmacokinetics | dynamics associated w/ the movement of drugs across the cell membrane --What the body does to the drug-- |
Pharmacodynamics | what the drug does to the body, the effects on man, the reason the drug is used |
Pharmacokinetics includes (CLADME) | Compliance Liberation Absorption Distribution Metabolism/Bio-transformation Excretion |
What is the main reason why drugs do not work? | Compliance |
The release of the drug from whatever form in which is has been administered is called....? | Liberation -drugs are formulated to be released at differing rates |
6 Routes of Drug Administration | Intravenous-injected directly into circulation [does not need to be absorbed] Intramuscular: injected into muscle Subcutaneous: injected just under skin Transcutaneous: inhaled or absorbed through skin Suppository: rectal delivery Oral: by mouth |
Absorption-Bioavailability -Indicates the fractional extent to which... | a dose of drug reaches its site of action |
Absorption-Bioavailability -Takes into account what 3 factors? [making if more useful to clinicans than absoprtion] | anatomical, physiological & pathological factors |
Absorption-Orally Administered drugs -Efficiency from GI tract depends on what factors? | 1. formulation of drug 2. uptake by transport mechanism intended for dietary vonsitutents vs passive diffusion 3. changes in intestinal motility, pH, inflammation, food, other drugs 4. variation among pop 5. age, pregnancy, pathological conditions |
First Pass Metabolism: --Route, Results, How they are given | orally ingested drugs are absorbed, enter portal vien and pass directly to the liver. Results in very little part drug exiting after metabolism Types are usually given IV |
Gastric Absorption: -Limited by -Facilitated by | Limited by: gastric-emptying time Facilitated by: pH (basic), bile (solubilize), active transport system, high blood perfusion |
Distribution: -Bound to....(acid drugs & basic drugs) | Bound to proteins Albumin (acid drug) alpha 1-acid glycoprotein (basic drug) |
Distribution: -The more widely the drug is distributed, the more likely the drug will be... | slowly eliminated |
Distribution: -Free vs Bound | Free/unbound can interact w/ site of action & cause biological response %free depends on physiological/biochemical parameters |
Fractional Protein Binding--Bound/Free Ratio -Normal circumstances -Factors that alter BF Ratio | bound/free drug ratio is relatively constant Altered by low albumin, abnormal pH, uremia, multiple drug displacements |
Fractional Protein Binding--Bound/Free Ratio -Net effect of factors altering BF ratio | heightened pharmacological response due to the increased free drug while the total serum drug levels may be in therapeutic range |
Fractional Protein Binding--Bound/Free Ratio -Net effect of factors altering BF ratio example | pH of blood shifts causing more of drug to be released from the protein--free drug concentration rises; represents a threefold increases in the pharmacological active free drug fraction w/out any change in total serum concentration--could cause toxicity |
Unbound Drugs: -Total drug (bound & unbound) are usually measured due to | sensitivity of the tests & ease in methodology |
Only (bound or unbound) drugs are metabolically active? | Unbound |
If over ___% bound, ____ drug should be tested | if over 85% bound, free drug should be tested |
Metabolism: -Primary metabolism occurs in -Secondary metabolism occurs in | Primary: liver Secondary: kidney, muscle & intestinal mucosa |
Two types of metabolism | 1. first pass metabolism (directly to liver, little parent drug exiting) 2. hepatic metabolism: purpose of liver is to transform nonpolar parent drug into a more polar (H2O soluble metabolite). |
Metabolites of hepatic metabolism are usually | less active |
Body's capacity to metabolize drug is dependent on ___? | Age -Increases from neonate to adult -Decreases w/ aging |
Elimination: -First Order | rate of change of concentration of proportional to the concentration of the drug. --constant % is removed over time |
Elimination: -Zero Order | constant amt is removed over time |
Elimination: which order will you see at -low concentrations -high concentrations | -low concentration--first order -high concentration--zero order (overdose) |
Elimination: -Routes | tears, saliva, bile, feces, expired air, sweat, breast milk |
Elimination: -drug testing of urine requires knowledge of | metabolite structures |
Bile may be ____ & the drug may be ____ | bile may be reabsorbed and drug recycled |
Drug clearance is affected by what 2 organs? | Kidney & Liver or conditions that affect profusion of theses organs (CHF or shock) |