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PHARMACOKINETICS

PHARMACOKINETICS. TPJ4M0 FINAL UNIT Mrs. H. Nightingale. PHARMACOKINETICS. Pharmacokinetics is the study of what the body does to a drug after administration. It is divided into four categories” ABSORPTION DISTRIBUTION METABOLISM EXCRETION. ABSORPTION.

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PHARMACOKINETICS

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  1. PHARMACOKINETICS TPJ4M0 FINAL UNIT Mrs. H. Nightingale

  2. PHARMACOKINETICS Pharmacokinetics is the study of what the body does to a drug after administration. It is divided into four categories” ABSORPTION DISTRIBUTION METABOLISM EXCRETION

  3. ABSORPTION Absorption refers to the ability and process of a dosage reaching the bloodstream. There are different routes of drug administration. The MOST COMMON are:ORAL, INTRAMUSCULAR, SUBCUTANEOUS, RECTAL, TRANSDERMAL, INTRAVENOUS.

  4. ABSORPTION Drugs administered intravenously do not require absorption since they immediately reach the vascular system. Oral agents must first be absorbed into the GI tract and may be metabolized there or by hepatic enzymes prior to reaching the circulation. Transdermallyadministered drugs do not pass through either the GI tract or the liver. The rate of absorption and extend of absorption are dependent on various factors.

  5. ABSORPTION Various factors such as: DRUG formulation Manufacturer Route of administration Intra-individual variations Another aspect of absorption is bioavailability. This is the fraction of the administered dose that reaches the systemic circulation. Bioavailability is 100% for IV injection!

  6. DISTRIBUTION Once the drug is absorbed, a certain drug concentration is reached in the body. The volume in which the drug is distributed is a product of the drug’s dose divided by the plasma concentration. (Vd)=dose/plasma concentration The distribution phase represents the early period in the dose/time curve when the drug is being circulated in the blood throughout the body and into the body fluids, organs and tissues.

  7. (Vd)=dose/plasma concentration Vd is directly related to the half=life of the drug. A drug with a large Vd compared to a drug with a small Vd, given similar clearance rates, will have a longer half=life and remain in the body longer. Half-life refers to the time required for the concentration of the drug in the body to be reduced by one half.

  8. EXAMPLE of Half-life For example…if the drug has a half life of 4 hours, 4hours after the initial dose, 50% of the drug will be removed. 8 hours after the initial dose, half of the remaining drug (25% of total) will be removed, for a total of 75% having been removed at that time, and so on….. Half life information is used to determine the correct drug dose required to attain the desired therapeutic range.

  9. METABOLISM Drug metabolism occurs primarily in the liver, and also in the GI tract. Drug metabolism is the process in which the body breaks down and converts the drug into active chemical substances. Knowing how the drug is metabolized is important for several reasons.

  10. METABOLISM When two or more drugs are administered at similar times how they metabolize will impact any drug interactions. In addition, drug metabolite can be either protein bound (inactive) or free (active). The drug dosage will depend on how the drug metabolizes. Factors that impact drug metabolism include genetics, environment, nutrition, and age.

  11. EXCRETION Drug excretion from the body occurs through the kidneys, or fluids excreted through the lungs, GI or skin. Renal dysfunction reduces drug clearance and may contribute to drug accumulation and increased risk of adverse drug effects.

  12. THERAPEUTIC RANGE

  13. VOCABULARY Absorption: The transition of drug from the site of administration to the blood circulation. Aminoglycoside: A group of injectable antibiotics active against a wide range of bacteria Bioavailability: A measure of how much of the durg makes it into the bloodstream and becomes available to the target tissue.

  14. VOCABULARY Cmax: the maximum concentration of drug in the blood. Cmin: the minimum concentration of drug in the blood. Distribution: the transition of drug from the blood circulation to the target tissue(s). Elimination: Removal or transformation of a drug in circulation, usually via the kidney and live. Elimination Half-Life: Time required for the amount of drug in the body to decrease %50.

  15. VOCABULARY Excretion: Elimination of drug via renal, biliary, or pulmonary processes. Half-life: A measurement of how long a drug stays in the blood. Loading Dose: Dose(s) of drugs given at the onset of therapy to rapidly provide a therapeutic effect. Use of loading dose prior to a maintenance dosage regimen will shorten the time required to approach a steady state. Maintenance Dose: A dosing regimen designed for chronic therapy.

  16. VOCABULARY PEAK Serum Concentration: The highest serum drug concentration that occurs following a single dose or t steady state within a dosing interval. Determining the exact peak requires numerous serial blood samples. Pharmacokinetics: The study of how drug levels change over time in the body. Steady State: Represents the equilibrium between the amount of drug given and the amount eliminated over the dosing interval. Steady state should not be confused with therapeutic range.

  17. VOCABULARY Therapeutic Range: Range of drug concentrations associated with high degree of efficacy and low risk of dose-related toxicity in majority of patients. Total Drug Concentration: The sum of unbound and bound drug in serum or plasma.

  18. Manufacturers of PHARMACEUTICALS

  19. SHIRES US Inc. NASDAQ STOCK EXCHANGE

  20. TYPES OF DRUGS ORAL: TABLETS, LIQUID, CAPSULES, INHALERS: ID- INTRADERMAL IM-INTRAMUSCULARIV- INTRAVENOUS Parenteral everything other than the GI tract Mostly by injections (syringe)

  21. PHARMACEUTICAL PACKAGING HANDBOOK

  22. OFFICIAL NAME = GENERIC NAME WHAT IS ON THE LABEL………. Trade Name: example PROVERA Generic Name: medroxyprogesterone United States Pharmacopeia: USP Form of drug: acetate tablets Dosage strength: 2.5mg/1tab

  23. What’s on the LABEL Trade name: E.E.S. 200 Liquid Generic Name: Erythromycin ethylsuccinate oral Form of drug: suspension United States Pharmacopeia: USP Total volume in container: 473 ML

  24. OTC = OVER THE COUNTER Trade name: MOTRIN Generic name: Ibuprofen Tablets United States Pharmacopeia: USP Dosage strength: 200mg Pain Reliever/Fever Reducer Total in container: 100 coated tablets

  25. Route of Administration Sublingual tablets should be placed under the tongue. Chewable tablets for oral administration. For intramuscular (IM) administration only. Unit-dose package of Diprivan for IV administration For oral inhalation only. Eg. Albuterol Sulphate Inhalation Solution, 0.5%* *potency expressed as albuterol. GIVE THE MEDICATION BY THE RIGHT ROUTE!

  26. STORAGE INFORMATION Some drugs must be stored under specific conditions to maintain their potency and effectiveness. Storage information will appear on the drug’s label. The label may have information about storage temperature, exposure to light, or the length of time the drug will remain potent after the container has been opened. Storage at the wrong temperature or exposure to light can trigger a chemical reaction that makes the drug unusable.

  27. FOR CANADA The DIN number must be on the packaging. DIN = Drug Identification Number and/or Notice of Compliance (NOC). More information at Health Canada www.hc-sc.gc.ca/ http://www.hc-sc.gc.ca/dhp-mps/compli-conform/gmp-bpf/docs/pol_0051-eng.php

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