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TNG Exam 3 > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

Dogs, cats, and foals have a neonatal period from _______ to ______. Pre-ruminants neonatal period is from 2 to 4 weeks.

A

birth to 2 weeks

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2
Q

The _______ period of all animals is from 2 weeks to weaning

A

pediatric

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3
Q

Neonates have (faster/slower) absorption of drugs, (higher/lower) absorption of drugs, and (higher/lower) bioavailability of drugs which changes as they age.

A

slower
higher
higher

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4
Q

What property of the neonatal GI system causes neonates to have increased bioavailability of drugs but despite high availability, they have delayed absorption of these drugs?

A

because they have increased intestinal permeability early in life (to get IgG from colostrum), however, they also have slow rate of gastric emptying.

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5
Q

Bioavailability of drugs usually decreases when given with solid foods. What happens to bioavailability on milk diet?

A

milk diets chelate drugs (Ca+ binds them) and makes them unable to be absorbed.

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6
Q

Neonates have decreased amount of efflux pumps and metabolizing enzymes… what effect does this have on drug absorption?

A

increases bioavailability
decreases first-pass effect
decreases activation of pro-drugs

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7
Q

Neonates have incomplete GI flora. What effect does this have on drug absorption?

A

lack of bacteria to metabolize drugs –> increased oral bioavailability

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8
Q

Within which animal will a drug have more oral bioavailability – Adult ruminant or neonatal ruminant?

A

neonate
adult ruminant has GI flora that will degrade the drug before it can get absorbed. whereas neonate does not have a complete GI flora, so more of the drug is available to be absorbed.
Pre-ruminants also have the esophageal groove, which when suckling allows drug to bypass the rumen (bypass degradation)

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9
Q

How is intramuscular administration affected in neonates?

A

they have low muscle mass so that can decrease bioavailability
but they also have increased body water content, so that can increase the bioavailability of water-soluble drugs

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10
Q

Transdermal administration in neonates leads to (increased/decreased) bioavailability

A

increased

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11
Q

T/F: neonates have larger extracellular fluid compartments due to more total body water. This leads to a larger volume of distribution for drugs which will affect the dose necessary to achieve a specific effect

A

true

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12
Q

Drugs that are (water/lipid) soluble and (time/concentration) dependent need the most dose adjustments in neonates due to their volume of distribution being affected.

A

water soluble
concentration-dependent
(ex. aminoglycosides – amikacin doses are much higher for neonates than adults)

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13
Q

If you are administering a lipid-soluble drug, how does drug dose change between neonate vs adult?

A

not really as dramatic of a change as we see in water-soluble drugs. This is because neonates have low body fat but high body water content, so drug distribution of a lipid-soluble drug evens out to what the distribution would be in adults with higher body fat, lower body water content.

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14
Q

T/F: dose adjustments are typically not needed between neonates and adults whe administering time-dependent antibiotics

A

true

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15
Q

T/F: there is not much difference in plasma protein binding with between neonates and adults when using lipid-soluble drugs (flunixin, tulathromycin, danofloxacin, florfenicol)

A

true

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16
Q

Phenobarbitol is more protein bound in neonates or adults?

A

adults – therefore we should be careful about dosing neonates because if less drug is bound, more drug is available for absorption.

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17
Q

When administering antibiotics to neonates, will they cross the BBB? will they cross in adults?

A

neonates – yes, drug is found in CSF
adults – no (because their BBB is complete)

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18
Q

For non-CSF therapeutics, you should (increase/decrease) the dose or (increase/decrease) the dosing interval in neonates.

A

decrease dose or increase dosing interval
this is because neonates are more susceptible to CNS toxicity.

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19
Q

T/F: hepatic metabolic capacity is impaired in neonates, thus drugs take longer to be metabolized. This changes as they age

A

true

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20
Q

Glucoronidation is a major pathway for drug metabolism. What is the concern about this pathway in neonates?

A

It is not fully developed
their ability to glucoronidate increases with age
except in cats, where it wont develop

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21
Q

The kidney is the major organ of drug elimination from the body, especially for water-soluble drugs and drugs that are …

A

ionized at urine pH

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22
Q

Which 2 species do not experience immature renal function during the entire neonatal period?

A

horses and ruminants
foals GFR and RBF becomes similar to adults by 2-4d
cattle and sheep by 1-3d

in other species, renal immaturity can affect drug elimination during the neonatal period (up to 3 weeks)

23
Q

Neonatal urine is acidic. This means that ______ drugs are excreted SLOWER and ______ drugs are excreted faster.

A

weak acids – excreted SLOWER (unionized, lipophilic drugs, more get reabsorbed) ex. sulfonamides
weak bases – excreted faster (ionized, hydrophilic, less likely to be reabsorbed) ex. aminoglycosides

24
Q

In summary, pharmacokinetics in neonates is described as: (pick correct one for each)
absorption: increased/decreased
distribution: increased/decreased
metabolism: increased/decreased
elimination: increased/decreased

A

absorption: increased
distribution: increased
metabolism: decreased
elimination: decreased

25
Q

Sepsis causes impaired blood flow within the body. Absorption of drugs is therefore (faster/slower).
This is why IV administration is recommended in cases of sepsis.

A

slower

26
Q

_________ therapy may be utilized to improve hemodynamic status (increased BF) and improve drug absorption in neonates with sepsis.

A

pressors
(dobutamine, norepinephrine, vasopressin, etc.)

27
Q

During sepsis, there is a redistribution of cardiac output. Blood is shunted AWAY from less vital organs such as the skin, kidneys, and gut, and blood is shunted TOWARD vital organs such as the heart and brain. What effect will this have on drug distribution?

A

it can increase drug reaching the brain and heart
(think anesthetics and metronidazole causing neurotoxicity)

28
Q

Sepsis causes alterations in the permeability of tissue membranes – more specifically endothelial damage and increased capillary permeability. Subsequently, interstitial edema occurs (third space phenomenon).
What effect does this have on the distribution of drugs?

A

increases the distribution of drugs with small Vd (hydrophilic drugs) which may cause a need to increase the dose.

29
Q

Sepsis causes decreased hepatic blood flow, reduced hepatocellular enzyme activity, and decreased CYP450 activity. What effect does this have on the metabolism of drugs in neonates with sepsis?

A

decreased metabolism

30
Q

Many neonatal patients with sepsis have prerenal, renal, or post renal azotemia. What effect does this have on drug clearance?

A

decreased

31
Q

Non-renal drug excretion is expected to (increase/decrease) in neonates with sepsis.

A

decrease

32
Q

In patients with sepsis, describe their pharmacokinestics in summary: (choose one for each)
absorption: increased/decreased
distribution: increased/decreased
metabolism: increased/decreased
elimination: increased/decreased

A

absorption: decreased (PO and extravascular routes)
distribution: increased (water-soluble drugs)
metabolism: decreased
elimination: decreased

33
Q

T/F: drug toxicity risk is decreased in septic patients because drug absorption is decreased

A

FALSE – toxicity risk is increased.

34
Q

Due to differences in metabolism or excretion, neonates are at higher risk for adverse effects when administering what drugs?

A

NSAIDs
you should increase the dosing interval or lower the dose

35
Q

Cox-2 inhibitors (meloxicam and firocoxib) are shown to be cleared (faster/slower) in neonates and thus may be considered “safer”

A

faster

36
Q

What parasiticide is safe in neonates and usually recommended to start after 14 d (small animal) and 1 month (foals)?

A

pyrantel pamoate

37
Q

which 2 parasiticides are considered safe in neonates?

A

pyrantel pamoate
fenbendazole

38
Q

Which 2 parasiticides should be avoided in dogs less than 6 wks and foals less than 4 months?

A

ivermectin and moxidectin

39
Q

what antiprotozoal drug should be avoided in neonates due to neurologic side effects?

A

metronidazole

40
Q

You are needing to treat a 2 week old puppy for coccidiosis, what antiprotozoal is safe for this neonate?

A

sulfadimethoxine

41
Q

__________ has been shown to be the safest anesthetic drug choice for neonates

A

propofol

42
Q

Which anesthetic drug is poorly tolerated in the first 3 weeks of life and would lead to prolonged elimination and recovery?

A

Ketamine

43
Q

Why is guaifenesin contraindicated in neonates?

A

prolonged elimination and recovery

44
Q

This drug, if given during the neonatal period, should be given at a lower dose because the BBB is 5-6x more permeable to it. It really should be all around avoided within the first 2-4 weeks of life.

A

pentobarbitol (a thiobarbituate)

45
Q

Why are thiobarbituates contraindicated within the first 2-4 weeks of life?
(what is the physiology behind absorption of these drugs?)

A

Neonates have less body fat than adults, therefore less drug is maintained in tissue depots. The drug initially goes from the blood into the brain and then back into the blood (instead of staying in tissue) to be reabsorbed into the brain d/t lack of fat.

The reabsorption back into the brain is the concerning part.

46
Q

Opioids have what effect on neonates?

A

sedative
we should choose drugs that have less respiratory depression

47
Q

T/F: benzodiazepines (midazolam, diazepam) are safe to use for neonatal sedation and muscle relaxation.

A

true

48
Q

___________ as a sedative is used with caution in neonates. They should be only used at very low doses and avoided if the patient has any respiratory or circulatory compromise (ex. septic neonate).

A

alpha-2 agonists

49
Q

If you need to administer 0.66 mL of a drug to a neonate, what size syringe would you choose to be most accurate and avoid overdosing the patient

A

1 mL

50
Q

What is the maintenance fluid rate for neonates?

A

80-100 mL/kg/day

51
Q

T/F: Neonates are more susceptible to fluid overload than adults, especially if they are sick or recumbent. During fluid therapy, you should monitor to avoid pulmonary edema development.

A

true

52
Q

Neonates are highly susceptible to which mineral overload?

A

sodium

53
Q

What are 2 ideal fluid choices for neonates?

A
  1. 0.45% sodium chloride
  2. 5% dextrose in water

add other electrolytes (Ca, Mg, K, Na, Cl)

TNG Exam 3 (6 decks)

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