Drug Dose and Response Factors Flashcards
Factors that influence drug dose and response can be grouped into these 3 main categories:
Relating to:
The animal
The drug
The environment
An important anatomic species difference to keep in mind when choosing drugs for ruminants vs monogastrics:
Different digestive tracts and pH
Rumen: 6
Stomach: 2-3
An important physiologic difference in cats that can inhibit metabolism of some drugs:
Cats don’t have salivary amylase
T/F: Cats have more acidic urine, while dogs and horses have more basic urine.
TRUE
What species is deficient in some drug-metabolizing enzymes?
Cats
What can make sensitivity to opioids change?
Presence or down-regulation of receptors
Herding breeds are predisposed to hypersensitivity reactions to some drugs, such as Ivermectin, due to the presence of this gene:
Multidrug Resistance (MDR-1) Gene
What breeds are especially sensitive to phenothiazines, such as acepromazine, due to increased vagal or parasympathetic tone leading to severe hypotension and bradycardia?
Brachycephalics
T/F: Genetic differences in individual animals are genetically tested routinely, so it’s common to know about them before they cause a problem.
FALSE
Most are occult and are not tested for except in cases of breed predisposition. Most genetic differences don’t have tests available.
Learn from individual’s drug response. Record ALL responses to medications.
T/F: Most dosages are based on the average adult animal.
TRUE
Adjust dose for lean, obese, dehydrated, etc.
Yellow discoloration of teeth and bones in young animals can be caused by what drug?
Tetracyclines
Giving fluoroquinolones, such as Baytril, to foals can have what adverse effect?
Damage to cartilage
Glucocorticoids given to young animals has what negative effect?
Inhibits normal growth
Presence of chronic disease affecting organ function, increased fat deposits, and decreased CO, renal function, albumin, lean body mass, and metabolic enzymes are factors to consider when determining drug dosages for what age group?
Geriatrics
T/F: Sex and temperament should not affect drug dosages.
FALSE
Consider pregnancy and lactation, and differences in M vs F body composition.
Aggressive dogs may need higher dose of sedatives d/t high sympathetic drive, while docile dogs may need lower doses.
Uncommon, abnormal drug reactions that are genetically determined and unpredictable:
Idiosyncratic (individual responses)
Which of the following are associated with idiosyncratic drug reactions?
Dose dependent Fever Facial swelling Skin eruptions Collapse Organ toxicity Bone marrow suppression
All except dose dependency!
fever, facial swelling, skin eruptions, collapse, organ toxicity, bone marrow suppression
Idiosyncratic reactions in cats given enrofloxacin present with:
Irreversible retinal damage in blindness
Zonisamide is associated with what idiosyncratic reaction?
Reversible neutropenia
What kind of drug reaction happens when drugs act as antigens or haptens, and requires prior exposure?
Drug Hypersensitivity reactions (allergic drug reaction)
What types of drugs are common in hypersensitivity reactions?
Human and animal products: plasma/blood transfusions, hormones, ALBUMIN.
Match the diseases to their effect on drug clearance:
- Hepatic Dysfunction
- Renal Insufficiency
- Congestive Heart Failure
A. Decreased drug excretion
B. Decreased renal excretion
C. Decreased drug metabolism
- Hepatic Dysfunction = Decreased Drug Metabolism
- Renal Insufficiency = Decreased Drug Excretion
- Congestive Heart Failure = Decreased Renal Excretion
Ruminants being tolerant to barbiturates is what type of drug tolerance?
Natural tolerance
Enzyme induction, increased excretion, and receptor down-regulation are what type of drug tolerance?
Acquired
