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 Pharmacology is the study of the properties (characteristics) and effects of drugs and
medications on the body. Drugs or medications are chemical agents used in the
diagnosis, treatment, and prevention of disease. They have intended effects,
unintended effects, and may have untoward effects (those that can be harmful to the
patient).
 There are indications and contraindications for each medication. Indications are the
therapeutic uses for a particular medication. Contraindications are cases in which you
should not give a patient medication.
 As an AEMT you must be familiar with the various names of drugs (trade, generic,
chemical, official), the sources of drugs, their classification, and sources where
information on drugs may be obtained.
 The manufacture of pharmaceuticals in most countries is regulated to protect
consumers. For example, standardized manufacturing is required for uniform strength
and purity.
 The Controlled Substances Act of 1970 is comprehensive legislation dealing with
narcotic and nonnarcotic drugs that have a potential for abuse and consists of five
categories or schedules according to abuse potential. Schedule I represents the highest
abuse potential and Schedule V is the lowest.
 Drugs must go through an approval process that includes animal studies and clinical
trials in humans before being approved for distribution. The Food and Drug
Administration (FDA) classifies newly approved drugs by several categories.
 There are special considerations for certain groups of patients when administering
medications: geriatric, pediatric, and pregnant patients. With pregnant patients, the
health of the mother is the priority in emergency situations. FDA Categories A, B, C,
D, and X rate risk to the fetus, with Category X representing the greatest risk.
 There are several medication concerns related to geriatric patients. Effects of a
medication may be delayed. Geriatric patients often take several medications, making
drug interaction possible. Alterations in mental status can lead to overdosing or
underdosing.
 As an AEMT, you are held responsible for safe and therapeutically effective drug
administration. This includes legal, moral, and ethical considerations.
 Drugs are grouped into classifications based on their effect on a body system, by their
effect on a system, or their mechanism of action (how they create the effect).
 To understand the effects drugs have on the body, you must have an understanding of
the nervous system. The sympathetic nervous system is responsible for the body’s
response to shock and stress (“fight or flight”). The parasympathetic nervous system
relaxes the body, controlling automatic functions during nonstressful times (“rest and
relax”).
 Adrenergic receptors cause a response in the target organ and are grouped as alpha-1,
alpha-2, beta-1, and beta-2. Some medications stimulate alpha and beta receptors,
whereas others may block specific receptors.
 Drugs that produce the same effects as sympathetic nervous system hormones are
sympathomimetics. Medications that have the opposite effect are sympatholytics.
 Agonists aid or increase effects. Antagonists antagonize or fight the effects of another
substance.
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Beta blockers are used to control blood pressure in some patients and heart rhythm
disturbances in others. Beta blockers work by filling a portion of the beta receptor
sites to prevent binding by beta stimulators that occur naturally in the body and can
be introduced as a medication.
Agonists to the parasympathetic nervous system are known as
parasympathomimetics, and antagonists are known as parasympatholytics. One of the
most commonly used parasympatholytics is the drug atropine that is used for
symptomatic bradycardia and exposure to organophosphates and certain chemical
nerve agents.
Analgesics include medications that relieve pain. The most common class of
medications used for analgesia in the prehospital setting comprises the opioid
agonists. Opioid antagonists reverse the effects of opioid drugs. Opioid agonistantagonists have agonistic and antagonistic properties. They are often preferred
because they can decrease pain but do not diminish the function of the respiratory
system or lead to dependence or addiction.
Sedative-hypnotics do what they suggest: sedate and produce hypnosis. They are
preferred for invasive procedures. Drugs that create sedation and hypnosis include
benzodiazepines, barbiturates, opioid agonists, and nonbarbiturate hypnotics.
Stimulants excite the central nervous system, while depressants slow brain activity.
Drugs that affect the cardiac system may affect heart rate, force of contraction, or
velocity of conduction through the heart. Cardiac glycosides, antiarrhythmics, and
antihypertensive medications are included in this group.
Antihypertensive medications include diuretics, vasodilator medications, ACE
inhibitors, and calcium channel blockers.
Certain medications prevent or minimize the effects of thrombi. These include
antiplatelet agents, anticoagulants, and fibrinolytics.
Drugs that affect the respiratory system include oxygen, over-the-counter
decongestants, bronchodilators, and xanthines.
Drugs come in many different forms, including solid, liquid, inhaled, topical,
transcutaneous, gels, and gases. Liquid intravenous medications are some of the most
common medications in the prehospital setting.
You should also know the various routes of medication administration and which
routes are used for the drugs you may administer in the prehospital setting. Routes
include enteral and parenteral.
Enteral drugs are those that are administered along any portion of the gastrointestinal
tract, including the oral and rectal routes.
Parenteral drugs are those that are administered through any route other than the
gastrointestinal tract and include intravenous (IV), intraosseous (IO), subcutaneous
(SC), intramuscular (IM), sublingual (SL), buccal, transcutaneous, intranasal, and
inhalation.
Once drugs are administered, they go through four stages: absorption, distribution,
metabolism, and excretion.
Pharmacokinetics is the study of the metabolism and action of drugs with particular
emphasis on the time required for absorption, duration of action, distribution in the
body, and method of excretion.
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Pharmacodynamics is the way in which a medication produces the response we
intended, also known as the mechanism of action. It also encompasses the factors that
may alter the intended response and any side effects or unexpected effects.
Factors that alter drug response include age, body mass, sex, environmental
conditions, time of administration, genetic factors, and psychological factors.
Responses beyond the desired effect are side effects and may occur even when a
medication is administered properly.
Unpredictable responses may occur when a medication is administered. These include
allergic reaction, serum sickness, and idiosyncratic reaction. Other effects that may
occur include cumulative effect, summation, potentiation, drug dependence, and drug
interaction.
Overall, it is important to learn as much as you can about the drugs you may be
allowed to administer in your area. Carry a pharmacologic reference to look up drugs
that may be unfamiliar.
You should also be aware of proper drug storage and security. Follow local protocols
for drug administration, and review pharmacology often.