Pharmacology

• Pharmacology


  The study of drugs
• Drug

  Any substance that, when taken into a living organism, may modify one or more of its functions
• Pharmacotherapeutics


  The area of pharmacology that refers to the use of specific drugs to prevent, treat, or diagnose a disease
• Pharmacotherapeutics is divided into


  • Pharmacokinetics
  • Pharmacodynamics
• Pharmacokinetics


  The study of how the body deals with the drug in terms of the way it is absorbed, distributed, and eliminated
• Pharmacodynamics


  The analysis of what the drug does to the body, including the mechanism by which the drug exerts its effect
• Toxicology


  The study of the harmful effects of chemicals
• Pharmacy


  Deals with the preparation and dispensing of medications
• Drug nomenclature

  • Chemical name
  • Generic name
  • Trade name
• Chemical name


  Refers to the specific compound's structure, fairly long and cumbersome
• Generic name


  The official or nonproprietary name, shorter
• Trade name

  The brand name, assigned to the compound by the pharmaceutical company
• Drug studies

  • Animal (preclinical) studies
  • Human (clinical) studies
• Animal (preclinical) studies


  1. Typically tested in animals initially, often using several different species

  2. Basic pharmacokinetic and pharmacodynamic properties of the compound is obtained

  3. Information on dosage and toxicity is also obtained from these animal trials
• Human (clinical) studies

  • Phase I
  • Phase II
  • Phase III
• Phase I


  Small number of healthy volunteers, purpose is to obtain some initial information about the pharmacologic actions, and the drug's possible toxic effects in humans
• Phase II


  A relatively small sample (200 to 300 people), to evaluate the effectiveness of the drug, and to assess the side effects and other risks
• Phase III


  Several hundred to several thousand subjects, additional information is obtained regarding the drug's safety and effectiveness in a large patient population
• Medication types


  • Over the counter drug/non prescription drug
  • Prescription
• Over the counter drug/non prescription drug


  Purchased directly by the consumer
• Prescription


  Ordered or dispensed only by an authorized practitioner (i.e., physician, dentist, or other appropriate health care provider)
• The dose of a drug must be large enough to allow an adequate concentration to reach the target site, thus producing a beneficial response, but not so excessive that toxicologic effects are produced
• Ceiling effect


  The point at which there is no further increase in the response, also known as maximal efficacy of the drug
• Dose-response curves


  Used to provide information about the dosage range over which the drug is effective, as well as the peak response that can be expected from the drug
• Potency


  Related to the dose that produces a given response in a specific amplitude, the more potent drug requires a lower dose to produce the same effect
• Quantal dose-response curves and the median effective dose are elements of drug safety
• Pharmacokinetics


  The study of the way that the body deals with pharmacologic compounds, including the manner in which the drug is administered, absorbed, distributed, and eventually eliminated from the body
• Routes of administration

  • Enteral (through the alimentary canal)
  • Parenteral (non-alimentary routes)
• Oral


  The most common method of administering medications, offers several distinct advantages such as ease of self-administration, relatively safe entry into the system, and avoidance of sudden increases in plasma drug levels
• Drugs given orally are subject to the first-pass effect where the drug is transported directly into the liver via the portal vein and may be metabolized and destroyed prior to reaching its site of action
• Sublingual and buccal


  Placing the drug under the tongue or between the cheek and gums, allows the drug to be absorbed through the oral mucosa into the venous system without being subjected to first-pass inactivation in the liver
• Rectal administration allows drugs to be given to a patient who is unconscious, or when vomiting prevents drugs from being taken orally
• Parenteral routes


  • Inhalation
  • Injection (intravenous, intra-arterial, subcutaneous, intramuscular, intrathecal)
  • Topical
  • Transdermal
• Intravenous

  Allows an accurate, known quantity of the drug to be introduced into the bloodstream over a short period of time, advantageous in emergency situations
• Subcutaneous


  Used when a local response is desired, or for a slower, more prolonged release of the medication into the systemic circulation
• Intramuscular


  The large quantity of skeletal muscle in the body allows this route to be an easily accessible site for parenteral administration, can be used to treat a problem located directly in the injected muscle
• Topical

  Applied directly to the skin or mucous membranes, most medications are absorbed fairly poorly through the epidermis and into the systemic circulation and are used primarily to treat problems that exist on the skin itself
• Transdermal


  Applying drugs directly to the surface of the skin with the intent that they will be absorbed through the dermal layers and into either the subcutaneous tissues or the peripheral circulation, requires the drug to be able to penetrate the skin and not be degraded by drug-metabolizing enzymes in the dermis
• Drugs that are given orally are subject to a phenomenon known as the first-pass effect where the drug is transported directly into the liver via the portal vein, where a significant amount of the drug may be metabolized and destroyed prior to reaching its site of action
• The dosage of the orally administered drug must be sufficient enough to allow an adequate amount of the compound to survive hepatic degradation and to eventually reach the target tissue