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Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-1Copyright © 2011 Delmar, Cengage Learning
12
6
9 32
4578
1011 1
1. Right drug
X
2. Right dose 3. Right time
4. Right route and technique
5. Right patient 6. Right documentation
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-2ACopyright © 2011 Delmar, Cengage Learning
Toxicityrange
Peak Concentration
Toxic effects (minimum toxic
concentration or MTC)
Desired drug action (minimum effective
concentration or MEC)
Dru
g co
ncen
tratio
n in
pla
sma
TimeDuration of effect
Subtherapeuticrange
Therapeuticrange
Onset ofactionA
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-2BCopyright © 2011 Delmar, Cengage Learning
Toxicityrange MTC
MEC
Peak concentration
Dru
g co
ncen
tratio
n in
pla
sma
TimeB
Subtherapeuticrange
Duration of action
Therapeuticrange
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-3Copyright © 2011 Delmar, Cengage Learning
Intramuscular Subcutaneous
Intravenous
Intradermal
90° 45°
25°10°–15°
Epidermis
Dermis
SubcutaneoustissueMuscle
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-4Copyright © 2011 Delmar, Cengage Learning
Luer-Lok tip
Barrel Rubberstopper
Plunger
5-cc syringe separatedand together (A)
3-cc syringeseparated (B)
Plunger
Rubberstopper
FlangeFlange
Slip-locktip
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-5Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-6ACopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-6BCopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-6CCopyright © 2011 Delmar, Cengage Learning
C
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-7ACopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-7BCopyright © 2011 Delmar, Cengage Learning
Lumen
Bevel Shaft
Point
PointLumen
Plastic sheath
Shaft Hilt Hub
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-8ACopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-8BCopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-8CCopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-9Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-10Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-11Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-12Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-13Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-14Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-15Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-16Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-17Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-18Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-19Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-20Copyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-21ACopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Figure 3-21BCopyright © 2011 Delmar, Cengage Learning
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Table 3-1Copyright © 2011 Delmar, Cengage Learning
Table 3-1 Parenteral Routes of Drug Administration
seluR lareneGetuoR
Intravenous (IV): within the vein
• rapid onset of action• higher initial body levels of drug• shorter duration of activity (need to be
redosed more frequently)• larger volumes can be given• irritating drugs or drugs that are painful via
other routes can be given IV (e.g., oxytet-racycline)
• increased risk of adverse effects (if drug given too rapidly, not sterile, or not prop-erly mixed)
• drug must be pure, sterile, and free of particles
• drug must be water soluble
Intramuscular (IM): within the muscle
• relatively rapid onset of action (generally about 30 minutes)
• rate of absorption depends on formulation (oil-based is slow, while water-based is fast)
• provides reliable blood levels• longer duration of action than IV (can dose
less frequently)• shorter duration of action versus oral
(generally)• absorption may be altered by vehicle pres-
ent in preparation• limited use for giving irritating solutions• convenient route in fractious animals
Subcutaneous (SQ, subQ, or SC): beneath the skin into the subdermis
• slower onset of action than IM• less reliable blood levels (similar to oral)• longer duration of action than IM (can be
given less frequently)• absorption may be altered by vehicle in
preparation• cannot use irritating solutions• generally used for giving larger volumes of
nonirritating, water-soluble solution
Intramammary: within the teat and udder sinuses
• fast and even distribution into mammary tissue
• particle size important (in nonlactating cows particle size is small to reduce udder irritation and provide prolonged drug retention)
• may contain thickening agents to modify rate of drug release
Intraperitoneal (IP): within the abdominal body cavity
• variable onset of action• variable blood levels• provides large surface area for drug
absorption• irritating solutions may cause peritonitis
• care must be taken so that the needle does not penetrate any organs; this could lead to peritonitis
• fi rst passes via portal system through liver, which could inactivate (or enhance) the drug’s action
Epidural/Subdural/Intrathecal: above the dura mater of the meninges, under the dura mater of the meninges, or into the subarachoid space of the meninges
• rapid onset of action localized to the cen-tral nervous system (CNS)
• used for diagnostic procedures and for administering some types of anesthetic agents
• disadvantages include potential for mis-performance resulting in spinal injection or drug moving cranially in the CNS
Intra-arterial (IA): within the artery
• used for treating a specifi c organ only, because very high drug levels are deliv-ered to a specifi c site
• may be accidental (e.g., given in carotid artery instead of jugular vein)
Intradermal (ID): within the skin
• injection given between dermis and epi-dermis
• very slow absorption• low blood levels obtained• used for local treatments or allergy testing
Intracardiac (IC): within the heart
• rapid drug levels attained because drug passes from heart to systemic circulation
• may be used in emergency situations
Intra-articular: within the joint
• injection given in the synovial space of joints
• sterile technique is critical• drug can be absorbed systemically
Intramedullary or Intraosseous (IO): within the medullary cavity of bone
• provides rapid blood levels• not commonly used and is painful• route of rapid fl uid administration in
smaller animals and birds• usually administered in the femur/humerus
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Table 3-2Copyright © 2011 Delmar, Cengage Learning
Table 3-2 Topical Drug Forms
Topical Drug Form Description
Aerosol Drug suspended in solvent and packaged under pressure
Cream Drug suspended in water–oil emulsion
Gel Drug suspended in semisolid or jelly-like substance
Liniment Drug suspended in oily, soapy, or alcohol-based substance applied with friction
Lotion Drug suspended in liquid for dabbing, brushing, or dripping on skin without friction
Ointment Drug suspended in semisolid, lipid-based preparation that melts at body temperature
Paste Drug suspended in semisolid preparation that retains its state at body temperature
Powder Drug suspended in powder for external lubrication or absorption
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Table 3-3Copyright © 2011 Delmar, Cengage Learning
Table 3-3 Local Routes of Drug Administration
Inhalation: inhaled into the respiratory system
• examples include gas-masking of animals, endotracheal administration of gas anesthe-sia, and nebulization of drugs
• establishes rapid blood levels because the alveoli of the lung provide a large surface area for absorption
• may be used for anesthesia, emergency procedures, and treatment of respiratory disease
Topical: applied on top of a surface
• topical routes of administration include skin, conjunctival, and subconjunctival
• used mainly in dermatology and ophthalmology
• may or may not be absorbed systemically• drug must fi rst dissolve and then penetrate
the skin by diffusion• good local effect• may be irritating• easy to administer• animal may chew/lick/rub off
Rectal • rectal drug absorption may be lower than with oral drugs due to small surface area or composition of the rectal formulation. Local irritation is possible with rectally adminis-tered drugs
Vaginal • vaginal drug delivery varies depending on drug formulation factors, vaginal physiology, age of the patient, and the phase of the estrous cycle of the patient
Transdermal • transdermal drugs may be mixed with a chemical to enhance skin penetration, which allows the drug to pass through the skin to the bloodstream
• transdermal drugs are delivered slowly and continuously for an extended period making plasma levels of a drug relatively constant; skin irritation is possible
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Table 3-4Copyright © 2011 Delmar, Cengage Learning
Table 3-4 Oral Route of Administration
stpecnoC lareneGetuoR
Oral (po) • most convenient route of administration for owner• slower onset of action• longer duration of activity• sometimes erratic and incomplete absorption because
drug is affected by gastric fl uids (acid)• absorption may be affected by gastrointestinal disease• relatively safe• drug must be able to get through gastrointestinal mucosa• drug need not be sterile• generally causes fewer adverse drug reactions• absorption in ruminants may be questionable with some
medications given orally
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Table 3-5Copyright © 2011 Delmar, Cengage Learning
Table 3-5 General Guidelines for Drug Administration (adapted from Pharmacological Aspects of Nursing Care
1. Enteric-coated tablets should not be administered with antacids, milk, or other alkaline substances, because enteric-coated agents require the acid environment of the stomach to be effective.
2. Enteric-coated tablets should not be crushed before administration; crushing will alter absorption.
3. Suspensions and emulsions must be thoroughly shaken immediately before use, because the separation that occurs after standing for a short period will alter the dose if used in the separated form.
4. Suspensions should never be administered IV. 5. Solutions administered parenterally or in the eye must be sterile to prevent
causing infection. 6. Solutions administered IV must be free of particulate matter that could serve as
an embolus. 7. Proper storage of solutions is very important to prevent contamination and
evaporation. 8. Skin integrity should be assessed for rashes or open areas before applying topical
medications, as these conditions will alter absorption time of the medication. 9. Transdermal therapeutic systems or patches allow drugs to pass through intact
skin and care should be taken when applying these to animals to prevent self-medication.
10. Proper disposal of transdermal patches is important to prevent their ingestion by animals or improper exposure to people.
Fundamentals of Pharmacology for Veterinary Technicians Chapter 3
Table 3-6Copyright © 2011 Delmar, Cengage Learning
Table 3-6 Causes of Drug Toxicity
Cause of Drug Toxicity
Example
Outright Overdose Dosing too frequently, dosing too high, administering too long
Relative Overdose Recommended dose was too much for this animal, due to
this individual animal, and improper route of administration
Side Effects Normal side effects associated with drug may occur at a higher level in this individual
Accidental Exposure Exposure of animal to drug that is absorbed through skin or inhalation or accidental ingestion
Interaction with Other Drugs
If drug A is highly protein bound and drug B is protein bound as well, the competition for protein binding will affect the amount of free drug (active drug) available to the animal
Incorrect Treatment Misdiagnosis: treatment causes toxicity levels of drug because the animal does not have the disease; for example, hormone replacement raises hormone levels above normal in healthy animal