Pharmacology Dr. Lou Fincher, ATC, LAT Associate Professor & Associate Chair Director, Athletic Training Education Program The University of Texas at Arlington
Learning Outcomes • Review the cognitive competencies from the Pharmacology Domain
Competencies in Athletic Training • Explain the laws, regulations, and procedures that govern storing, transporting, dispensing, and recording prescription and nonprescription medications (Controlled Substance Act, scheduled drug classification, and state statutes).
Managing Medications • http://www.nata.org/statements/consensus/ConsensusStatementManagingMedication.pdf
Drug Classification • Over-the-counter (OTC) • Prescription (Rx) • Controlled substances (scheduled)
Drug Classification • Controlled Substances • Greater potential for abuse than prescription drugs • Greater restriction in storage, distribution, and record keeping
Drug Classification • Controlled Substances • Schedule I • Schedule II • Schedule III • Schedule IV • Schedule V –highest potential for abuse – lowest potential for abuse
Drug Classification • Controlled substances • most narcotic pain prescriptions are classified as Schedule III • anabolic steroids are also Schedule III
Competencies in Athletic Training • Identify appropriate pharmaceutical terminology and abbreviations used in the prescription, administration, and dispensing of medications.
Terminology & Abbreviations • Abbreviations for dosage • qd – every day • bid – twice a day • tid – three times a day • qid – four times a day • q 3 h – every 3 hours
Competencies in Athletic Training • Identify information about the indications, contraindications, precautions, and adverse reactions for common prescription and nonprescription medications (including herbal medications) using current pharmacy resources
Common OTC and Rx Meds • Treatment of musculoskeletal disorders • NSAIDs • corticosteroids • analgesics
Common OTC and Rx Meds • Treatment of infections • antibiotics • antifungals • antivirals
Common OTC and Rx Meds • Management of asthma • short acting β2-agonists • long acting β2-agonists • corticosteroids • leukotriene modifiers • cromones
Common OTC and Rx Meds • Treatment of GI disorders • antigas • antacids • antidiarrheals • antiemetics
Common OTC and Rx Meds • Treatment of colds & allergies • antihistamines • decongestants • antitussives • expectorants
Common OTC and Rx Meds • Herbal supplements • St. John’s Wort • gingko • ginseng • garlic • echinacea
Competencies in Athletic Training • Explain the concepts of pharmacokinetics and the suspected influence that exercise might have on these processes.
Pharmacokinetics • How the body handles a drug • Four phases (ADME process) • absorption • distribution • metabolism • elimination
Absorption • For a drug to produce a therapeutic effect, it must be absorbed into the bloodstream and distributed through the circulation
Absorption • Absorption requires the drug molecule to move across a membrane • simple diffusion • active transport • facilitated diffusion
Absorption • Oral absorption • drugs taken by mouth pass to the stomach & then the intestine • they are absorbed from the GI tract into the circulatory system • the quicker the drug dissolves, the quicker it can be absorbed
Absorption • First pass effect • some drugs will pass through the liver before being distributed throughout the blood stream • when these drugs pass through the liver, they are broken down (metabolized) into inactive, less active, or more active compounds
Absorption • Absorption is also affected by solubility of drug • lipid soluble drugs can easily pass through the blood-brain barrier to affect the CNS • water soluble drugs are more easily and quickly excreted
Absorption • Oral absorption • almost all drug absorption takes place in the small intestine • most drugs recommend that they be taken with a full glass of water • this liquid helps move the drug more quickly into the intestines • food in the stomach delays the absorption of a drug
Absorption • Oral absorption • gastric emptying can occur in as little • 10 minutes on empty stomach • Hours on a full stomach (large meal) • some foods can interfere with drug absorption • Dairy products & tetracyclines (antibiotic)
Absorption • Oral absorption • some drugs are designed for delayed absorption • extended release • controlled release • these drugs usually contain a larger dosage to account for the delayed time in absorption
Absorption • Oral absorption • delayed absorption • many extended release drugs contain an enteric coating • doesn’t dissolve until it reaches the small intestine
Absorption • Oral absorption • Extended release drugs SHOULD NOT be cut, crushed, or broken in half
Absorption • Exercise decreases absorption of drugs taken by mouth • blood is diverted away from the GI tract to the skeletal muscles • when the body absorbs less of a drug, its therapeutic effectiveness is decreased
Absorption • Sublingual & buccal • dissolve directly in the mouth • rapid absorption due to rich blood supply in the mouth • provide a rapid therapeutic effect • eliminates the first pass effect • nitroglycerin provides a peak response in 3-5 minutes
Absorption • Rectal • drug dissolves in the rectum and is absorbed into the bloodstream by the hemorrhoidal veins • advantages of rectal administration • good for those suffering from nausea & vomiting • disadvantages of rectal administration • absorption varies & is often incomplete
Absorption • Intravenous • no true absorption – they are injected directly into bloodstream • Intramuscular • faster absorption than subcutaneous • Subcutaneous faster than oral
Absorption • Topical • slow absorption – drug must pass through the skin • Inhalation • rapid absorption (<5 min.)
Distribution • Once absorbed into the bloodstream, the drug can be distributed to target sites throughout the body • Exercise increases the distribution of most drugs • increasing cardiac output increases the speed at which the circulatory system carries the drug to its target site
Distribution • Affected by a drug’s lipid solubility • drugs with high lipid solubility can easily penetrate fat stores and cross membrane barriers → providing a broader distribution • water soluble drugs can be easily eliminated from the body • fat soluble drugs can be stored in the body, providing longer lasting effects
Distribution • Onset of action • time it takes for the drug to reach a concentration level large enough to cause a noticeable biological effect
Distribution • Duration of action • the length of time the drug produces a therapeutic effect
Distribution • A drug’s most intense effects occur during the peak serum concentration • when the highest level of the drug is in the bloodstream
Metabolism • Clearing process that breaks down substances into water soluble form for easy excretion • primary site → liver • may also occur in the kidneys, GI tract, and lungs.
Metabolism • Exercise can decrease the clearance of some drugs due to blood being diverted away from the GI, kidneys, and liver to the working skeletal muscle
Metabolism • HOWEVER, since the duration of the drug’s effects is usually longer than an exercise session, the overall effect of exercise on drug metabolism is insignificant or negligible.
Elimination or Excretion • Removal of the drug from the body • primary method • kidneys → urine • other methods • Biliary tract → feces • Lungs → respiration • Sweat glands → perspiration
Elimination or Excretion • Exercise can slow the rate of excretion since blood flow will be diverted away from the kidneys to the working skeletal muscle • Excretion rate also affected by the drug’s half-life
Competencies in Athletic Training • Explain the concepts related to bioavailability, half-life, and bioequivalence.
Bioavailability • The amount of drug actual active in the body tissues • Typically just a fraction of its dosage size
Bioavailability • If a drug’s bioavailability is 50%, then the body will only absorb 250 mg of a 500 mg dose. • Naproxen (Naprosyn) – bioavailability is 95% • Voltaren – bioavailability is 50-60%
Bioavailability • Bioavailability is affected by • rate at which a drug dissolves in the GI tract • amount and rate of drug absorbed • formulation • capsule, tablet, injection, oral, etc. • first pass effect (liver)
Half-Life • The time required for the body to eliminate one-half of a dosage of a drug by regular physical processes • if a drug has a half-life of 8 hours, then it will take 8 hours for the blood concentration of the drug to be decreased by 50%
Half-Life • Naproxen (Naprosyn) has a half-life of 12 -17 hours • it will take 12 hours to reduce the blood concentration of a 500 mg dose to 250 mg • Water • soluble drugs will have shorter half-life than lipid soluble drugs • Lipid soluble drugs • will remain in the system longer.