Download Chapter 10: Principles of Pharmacology

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• Although the science of pharmacology has evolved into a sophisticated area of health care,
certain medications discovered in ancient times are still in use.
• Paramedics need to be familiar with the rules and regulations implemented under the
Controlled Substances Act (also known as the Comprehensive Drug Abuse Prevention and
Control Act) of 1970.
• Schedule I medications may not be prescribed, dispensed, used, or administered for medical
use.
• All Schedule II through V medications require locked storage, significant record keeping,
and controlled wasting procedures.
• Every medication in the United States is given three distinct names:
– Chemical name
– Generic name
– Brand name
• The United States Pharmacopeia–National Formulary and Physicians’ Desk Reference
provide detail about thousands of medications.
• Direct sunlight, extremes of heat and cold, and physical damage to medication containers
can make medications ineffective or unsafe for use.
• Controlled medications require additional security, record keeping, and disposal
precautions. They must be in locked storage or continuously held by an (on-duty) EMS
provider responsible for administration.
• As a medication is administered, it begins to alter a function or process in the body. This
action is known as pharmacodynamics.
• Medications are developed to reach and to bind with particular receptor sites of target cells.
• Newer medications are designed to target only very specific receptor sites on certain cells in
an attempt to minimize side effects.
• A wide variety of factors determine how a particular medication will affect a patient and
may influence the choice of medication, dose, route, timing, manner of administration, and
monitoring necessary after a patient receives a medication.
• The terms side effect and adverse effect are often used interchangeably, but adverse effect is
usually meant in prehospital settings. Adverse effects are the undesired or harmful
responses to a medication.
• The relationship between the median effective dose and the median lethal dose or median
toxic dose is known as the therapeutic index or therapeutic ratio.
• Repeated exposure to a medication within a particular class has the potential to cause a
tolerance affecting other medications in the same class.
• Patients receiving multiple medications, drugs, or other chemicals are at risk of an
unintended interaction between or among the various substances, possibly with unexpected
results.
• As a medication is administered, the body begins a complex process of moving the
medication, possibly altering the structure of the medication, and, ultimately, removing the
medication from the body. The medication dose, route of administration, and clinical status
of a particular patient will largely determine the duration of action and effectiveness of the
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medication.
Many medication factors such as the size of medication molecules, the ability to bind with
other substances in the body, and the ability to dissolve in certain body fluids determine
which cells, tissues, and organs a particular medication will reach.
Biotransformation is a process that has four possible effects on a medication absorbed into
the body:
– Can become active, producing wanted or unwanted clinical effects
– Can be changed into another active medication
– Can become completely or partially inactivated
– Can be transformed into a substance that is easier for the body to eliminate
Paramedics are constantly at risk for a cognitive error (such as choosing the wrong
medication or dose) or a technical error (such as administering more volume of medication
than intended).
There are six rights of medication administration:
– Right patient
– Right medication
– Right dose
– Right route
– Right time
– Right documentation and reporting
Medications and medication groups often used in the prehospital setting are for airway
management and respiratory management; for the cardiovascular, gastrointestinal, and
neurologic systems; and blood products and medications affecting the blood.