Pharmacology Terms, Drug Sources and Natural Sources

Terms and Abbreviations Related to Pharmacology

• Adverse effect refers to undesired and potentially harmful side effects of medications.
• Bolus is a dose of medication that is administered rapidly intravenously.
• Contraindication is a reason against giving a medication.
• Absorption describes the process by which medications are taken into the body.

Drug Sources

• Drugs can originate from natural sources.
• Drugs can originate from chemical synthesis.
• Drugs can originate from biotechnology.

Natural Sources

• Plants such as Atropine and Morphine are natural sources.
• Minerals such as Silvadene cream for burns and OTC antacids are natural sources.
• Animals such as Pigs which are porcine, contain hormones and insulin.
• Cows which are bovine produce Thrombin.
• Horses which are equine produce Premarin.

Chemical Synthesis

• Most drugs are synthetic, like Demerol.
• Some drugs are semisynthetic, like Amoxicillin.

Biotechnology

• Humulin, Alteplase, and growth hormone come from biotechnology.

Drug Classifications

• Therapeutic action
• Physiologic action
• Body system
• Chemical type

Drug Subcategories

• Subcategories are especially useful in determining function.
• Medical terminology is applied to determine the use of the drug.
• Some drugs are classified in more than one category, such as Ranitidine (Zantac).

Therapeutic Action

• Anti-inflammatory drugs reduce Inflammation.
• Analgesics reduce pain.
• Thrombolytics break down blood clots.
• Antipyretics Reduce fever.

Physiologic Action

• Vasoconstrictors narrow blood vessels.
• H₂ receptor antagonists prevent the production of gastric acid.

Affected Body System

• Dermatologic Agents such as Cortisone cream.
• Gastric Agents such as Tagamet, Zantac and Reglan.

Chemical Type

• Benzodiazepine drugs include of Valium, Versed, and Ativan.
• Barbiturate drugs include Pentothal, and Brevital.

Drug Classifications and Subcategories

• Ranitidine (Zantac) has multiple classifications.
• It's therapeutic classification is as an antacid.
• It's physiologic classification is as an H₂ blocker.
• It's body system classification is as a gastric agent.
• Some drugs have more than one therapeutic action.
• Aspirin, for example, is an antipyretic, analgesic, and anti-inflammatory.
• Examples of other drug classification subcategories include:
  • Anticoagulants
  • Cholinergics
  • Barbiturates
  • Benzodiazepines
  • Urinary tract agents
  • Alpha-adrenergic blockers
• Drugs can be classified as prescription, including controlled substances, or over the counter, or OTC.
• Information about drug sources, classifications, and subcategories is used to understand:
• How to handle the drug.
• How to use the drug.
• How the drug works.

Medication Orders

• Prescriptions are not used during surgery.
• Unlike prescriptions, drugs used in surgery are ordered by a physician.
• Written prescriptions can be difficult to interpret due to differing handwriting.
• E-prescribing can significantly reduce medication errors.
• Standing orders in surgery are known as "protocol" or surgeon's preference card.
• Verbal orders are needed is special circumstances.
• Stat orders are immediately needed one time only, and are given in urgent, unpredictable situations.
• PRN orders are also on the medication preference card.

Parts of a Medication Order

• Drug name
• Strength
• Volume

Drug Distribution Systems

• Drugs are only dispensed by pharmacists.
• Drugs are dispensed by hospital pharmacy, operating room (OR) satellite pharmacy, or OR medicine cabinet/cart.
• Hospital pharmacies release special PRN items, and special antibiotic preparations.
• OR satellite pharmacies are used in hospitals with many ORs.
• They use containers labeled for each procedure.
• These containers are returned after each case, and inventoried, billed, and restocked.
• The medication order will list standard items needed.
• Items are then pulled per preference card, charged on the patient record, and restocked PRN.
• Computer-automated dispensing systems are used for medication distribution in surgery.
• Bar-code scanning system allows an approved user access to particular medications ordered for a particular patient.

Drug forms or Preparations

• Solid drugs are rarely used in the OR: Patient is NPO
  • Pills
  • Capsules
  • Tablets
  • Powders, freeze-dried
  • Reconstituted
    • Many antibiotics
    • Dantrolene
• Semisolids:
  • Used in surgery
  • Creams, foams
    • Silvadene cream
    • Estrogen cream
  • Ointments, gels
    • Lidocaine jelly
    • Neosporin ointment
• Liquids Solution
  • Chemical dissolved in liquid Suspension
  • Chemical undissolved in liquid Emulsion
  • Mixture of water and oil bound together with emulsifier.
• Solutions IVs, antibiotic irrigation, heparin irrigation
• Suspensions Cortisporin, Celestone
• Emulsions Propofol (Diprivan)
• Gases Inhalation anesthetic agents Nitrous oxide (N₂O) Desflurane (Suprane)
  • Supplied in liquid form, but anesthesia machine vaporizer converts into gas to administer agent

Drug Administration Routes

• Medications are formulated for a specific route, and are non-interchangeable.
• There are two categories of medication
  • Enteral
  • Parenteral
• The most common route
  • Oral , which are very rare in surgery
• Some topical agents work at the local site, wheras some exert a systemic effect throughout the entire body Topical
  • Antibiotic ointment (Neosporin)
  • Antibiotic irrigation (used commonly in surgery) Variation: Instillation Contrast media, lidocaine jelly Variation: Inhalation Inhalation anesthetic gases
• Parenteral Subcutaneous = SC Intramuscular = IM Intravenous = IV IV injection
• All local anesthesia injections at surgical site are parenteral route Tissue layers, port sites
• Parenteral: Less common routes Intradermal (TB test) Intra-articular Intrathecal Intracardiac

Drug Forms/Preparations and Administration Summary

• Medication orders in OR are different from those in doctor's office - While retaining some of the same elements.
• Hospitals distribute medications in various ways.
• Medications are available in different forms.
  • Specific to administration routes
  • Knowing the routes and abbreviations is vital.

Pharmacokinetics and Pharmacodynamics

• Pharmacokinetics is the study of how the body processes drugs.
• Pharmacodynamics examines how the action of the drug affects the body
• There are 4 main processes that it includes.
  • Absorption
  • Distribution
  • Biotransformation
  • Excretion

Absorption

• A drug being taken into the body.
• The body system involved varies by administration route.
  • Skin
  • GI
  • IV
• Absorption time can vary by:
  • Administration route
  • Vascular supply to area ↑ vascularity = ↑ absorption rate
  • Formulation or solubility of drug, also known as “Dissolvability"
• The oral route absorption rate varies.
• Factors affecting rate
  • Formulation of the drug
  • Route of administration
  • Extent of blood supply to the site of administration

Distribution

• Drug is present in the bloodstream, and it is carried throughout body to the site of action
• Body system involved: Circulatory
  • Drugs can affect areas other than the intended area, such as how Aspirin for pain also slows blood coagulation.
• Distribution is also affected by
  • General circulatory status
  • Blood supply to site of action
    • Example: Antibiotics/bone
• Plasma protein binding (PPB)
  • Major impact
  • Because medications are carried by/in blood

Distribution – PPB

• Understand the blood components.
  • Formed Elements:
    • Red blood cells (RBCs)
    • White blood cells (WBCs)
    • Thrombocytes
  • Plasma
    • Fluid
    • Also contains many proteins
• Drugs can bind to proteins, but it Depends on:
  • Number of plasma proteins
  • Drug-binding affinity
• If the drug is bound to proteins, the drug cannot reach the site of action.
• Drugs can compete for binding sites.
  • The Process is reversible.
  • Released when drug concentration is low.

Biotransformation

• Commonly called Metabolism.
• All drugs eventually get to the liver, which is also known as the Biliary System.
  • Where the liver will break them down so they are less toxic and able to be excreted.
• Factors that can affect this action includes
  • Liver health
  • First-pass effect
• Only Unbound drugs can be biotransformed.
• The drug will either go through,
  • Some drugs may only be completely Broken down
  • Other drugs may not be broken down at all.
  • Or Most are partially changed.
• Prodrugs are,
  • Given in an Inactive form.
  • Biotransformed by liver into active drug
  • Several prodrugs are available; few are used in surgery.
• “First-pass effect"
  • Many Drugs are altered or nearly inactivated by the liver.
  • Repeated dosing overcomes first-pass effect

Excretion

• When a drug is is Eliminated from the body.
• Only unbound drugs are excreted.
• This Primarily occurs by Kidney and our Urinary System.
  • Others this includes Bile, skin, or even lungs
• There are two main renal processes.
  • Glomerular filtration
  • Tubular secretion
• This all Depends on Glomerular filtration rate this includes.
  • Blood pressure
  • Blood flow to the kidneys
• Some drugs may be reabsorbed.

Pharmacodynamics

• Pharmacodynamics is defined the study of drugs and their actions in the body.
  • Involves both the Drug's effects on the body, and on the Body's response to drug
• Agonists are drugs that bind or have an affinity for a receptor and cause a particular response
• Antagonists are drugs that bind to a receptor and prevent a response
• Synergists are drugs that enhance the effect of another drug
• Indication includes the Reason or purpose for giving a medication
• Contraindication includes the Reason against giving a particular drug
• Onset includes the Time between administration of a drug and the first appearance of effects
  • Where as Duration includes Time between onset and the disappearance of drug effects
  • Side Effect includes Predictable but unintended effect of a drug
• While a Adverse Effect includes Undesired, potentially harmful, side effects of drugs
  • This consists of , Nausea, vomiting, Drug toxicity, Hypersensitivity, Idiosyncratic (unusual) reactions
• Hypersensitivity
  • is an Adverse Effect that the Results from previous exposure to the drug or a similar drug
• Idiosyncratic drug reaction
  • Includes When the exact mechanism of an adverse drug effect is not known