Blood flow pain stress hunger fasting food and pH affect drug absorption iv

Blood flow pain stress hunger fasting food and ph

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Blood flow, pain, stress, hunger, fasting, food, and pH affect drug absorption iv. Approx. 80% of drugs are taken by mouth (enteral route) 1. Oral, Sublingual (under the tongue), Buccal (into the cheeks), Rectal v. Parental drugs – do not pass through GI tract (Liquid or dry-needs liquid added: reconstitution) 1. Injectable drugs 2. Intravenously (IV): Into a vein (fastest, immediate and complete) 3. Subcutaneously (SubQ): Into a subcutaneous tissue (rapid if highly water soluble & good circulatory blood flow) 4. Intramuscularly (IM): into a muscle tissue; deltoid a good location, gluteus maximus is not (rapid if highly water soluble & good circulatory blood flow) 5. Transdermal: Topical a. Apply directly on skin: immediate onset of action b. Absorb through skin: delayed onset of action c. Skin, eyes, ears, nose, lungs (inhalation), rectum, vagina 6. Intraarterial 7. Intrathecal 8. Intraarticular vi. First-pass effect 1. Every drug given by the mouth will go through this, all others forms will not 2. The more blood flow to the muscle, the quicker it gets absorbed 3. Medication taken by mouth go from intestines liver (broken down here) portal vein 4. In the liver, some drugs are metabolized to an inactive form and are excreted, thus reducing the amount of active drug available to exert a pharmacologic effect (first pass effect) vii. Bioavailability 1. Percentage of administered drug available for activity 2. How much of the drug is left to still be used in an active form 3. Orally administered drugs bioavailability affected by absorption and first pass effect, always less than 100% & varies based on the rate of first pass effect 4. Bioavailability of IV drugs is ALWAYS 100% 5. Factors that affect bioavailability a. Drug form such as tablet, capsule, sustained release beads, liquid, transdermal patch, suppository, inhalation b. Route of administration- enteral, topical, or parenteral c. Gastric mucosa and motility d. Administration with food and other dugs e. Changes in liver metabolism caused by liver dysfunction or inadequate hepatic blow flow
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f. A decrease in liver function or a decrease in hepatic blood flow can increase the bioavailability of a drug, but only if the drug is metabolized by the liver i. Less drug is destroyed by hepatic metabolism in the presence of a liver disorder b. Distribution: Movement of drug by circulatory system to intended site of action; movement of the drugs from the circulation to body tissues i. Influenced by 1. Rate of blood flow to the tissue a. Anything that cuts blood flow will slow down distribution process b. Adequate blood supply determines how well drug is distributed 2. Drug’s affinity to the tissue 3. Protein binding a. Part that is bound w/ drug is now inactive, not available to interact with tissue receptors b. Free drugs is the active part, able to exit blood vessels and reach their site action c. Highly protein-bound drugs – more than 90% bound to protein d. Weakly protein-bound drugs – less than 10% bound to protein ii. Blood-Brain Barrier (BBB) 1. Blood vessels in the brain have a special endothelial lining where the
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