Drug Interactions (Allen-Durrance) Flashcards

1
Q

Drug list (10)

A
  1. Levetiracetam
  2. Phenobarbital
  3. Cimetidine
  4. Chloramphenicol
  5. Ketoconazole
  6. Omeprazole
  7. Sucralfate
  8. Diazepam
  9. Potassium Bromide
  10. Digoxin
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2
Q

Collard greens have vitamin K

A

Interact with warfarin

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3
Q

Potassium Bromide interaction in FL

A

NaCl

Dogs drinking salt water when on Potassium Bromide

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4
Q

Polypharmacy

A

When you administer multiple drugs for one patient

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5
Q

Possible Drug interaction consequences

A

None

Altered therapuetic efficacy

Altered duration of action

Altered intensity of side effects

Novel effects

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6
Q

Drug interaction categories

A
  1. Incompatibilites
  2. Pharmacokinetic interactions
    * some drug interactions is altering plasma level of drug
  3. Pharmacodynamic interactions
    * modulating drugs affect at a given plasma concentration
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7
Q

Physical incompatibilities

A

Separation

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8
Q

Chemical Incompatibilies

A
  1. Precipitation
  2. Chelation
  3. Binding
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9
Q

Consequences of Incompatibilites

A

Damage from toxic compounds

Particulate emboli

Tissue irritation (pH changes)

Therapeutic failure

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10
Q

Drugs incompatible with EVERYTHING

1.

2.

3.

4.

5.

6.

A
  1. Aminoglycosides
    * Stop fluids even
  2. Diazepam
    * Likes to precipitate
  3. Digitalis glycosides
  4. Pentobarbital
  5. Sodium bicarbonate
  6. Theophylline derivatives
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11
Q

Drugs with limited compatibility

1.

2.

3.

4.

5.

6.

A
  1. Dobutamine
  2. Dopamine
  3. Epinephrine
  4. Norepinephrin
  5. Tetracyclines: Doxy
  6. Parenteral antifungals: amphotericin D
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12
Q

Ketamine and Diazepam

A

Precipitates

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13
Q

Doxycycline and Calcium Gluconate

A

Chelation

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14
Q

Doxy and patient with chronic kidney disease

A

Kidney disease

  • Cant bind phospohrus
  • Give aluminum hydroxide to bind excess phosphorus

Aluminum hydroxide precipitates with the doxy I think

  • Gets pooped out
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15
Q

Tums

A

Calcium supplements

Hyperparathyroidism post-op can cause hypocalcemia

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16
Q

Drugs that bind to plastic

A

Insulin

Diazepam

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17
Q

Diazepam

A
  1. Bind to plastic
  2. Light sensitive
  3. Now replaced by midazolam (none of these problems)
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18
Q

Sulcralfate

A

Bind irritated areas in the stomach and coats stomach

Drugs it Binds to (which then get pooped out)

  • Tetracyclines
  • Fluoroquinolones
  • Cimetidine
  • Phenobarbital
  • Griseofulvin (antifungal)
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19
Q

Pharmacokinetic Interactions

A

Common changes in

  • Absorption
  • Distribution
  • Metabolism
  • Elimination
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20
Q

Drugs that increase pH of stomach

A

Drug examples

  • Omeprazole
  • Famotidine
  • Antacids

Decreases absorption of weak acids

  • Ketoconazole

Increase absorption of weak bases

*This can be a longer term interaction, prolonged increase of stomach pH

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21
Q

Gastric pH changes on Absorption

A

Inc pH

  • antacids increase pH
  • increases absorption of weak bases
  • decreases absorption of weak acids

Dec pH

  • inc absorption of weak acids
  • dec absorptio of weak bases
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22
Q

Metoclopramide

A

Prokinetic: tries to get stuff out of stomachfaster

Causes less absorption of delayed release medications

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23
Q

Epinephrine

A

Non selective alpha and beta receptor stimulant

  • vasoconstriction via alpha 1 receptors

Lasts longer when given with lidocaine

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24
Q

Licocaine

A

Makes epinephrine last longer

25
Q

Prozinc

A

Insulin (protamine zinc)

  • harvest it from salmon
  • neutral pH

Saline pH: 4.2

*Insulin plus saline lowers pH of insulin and slows absorption

  • can cause hyperglycemia
26
Q

Saline

A

pH of 4.2

lowers pH of neutral drugs

can slow absorption of insulin (neutral pH)

27
Q

Protein Binding

A

Distribution

Drugs that bind to albumin

  • Bound drugs are inactive
  • Unbound drugs are active component

Competition when two highly protein bound drugs administered simultaneously

  • Erythromycin
  • Doxycycline
  • NSAIDs
  • Amphoteracin B: toxic to kidneys
  • Furosemides
28
Q

Altered drug-albumin binding

Decreased production albumin

A

Low albumin

  • Decreased production
    • Acute phase (stress, injury, SIRS)
    • Hepatic disease
    • Malnutrition
    • Aging
    • Malignancies
29
Q

Altered drug-albumin binding

Capillary leakage from serum to tissues

A

Low albumin

  • Capillary leakage from serum to tissues
    • Burns
    • SIRS
    • Pregnancy
    • Diabetes mellitus
    • Pulmonary edema
30
Q

Altered drug-albumin binding

Increased elimination of albumin

A

Low albumin

  • Increased elimination
    • Nephrotic syndrome
    • Burns (wound loss)
    • Iatrogenic binding to starch
31
Q

Altered drug-albumin binding

Displacement by endogenous molecules

A

Normal albumin

  • Displacement by endogenous molecules
    • Bilirubin (hyperbilirubinemia)
    • Urea
    • Other waste products (hippuric acid, p-cresol)
    • Free fatty acids
    • Hormones
32
Q

Altered drug-albumin binding

Displacement/modification by exogenous molecules

A

Normal albumin

  • Displacement/modification by exogenous molecules
    • Highly albumin-bound antibacterials
    • Other drugs
      • aspirin
      • furosemide
33
Q

Pharmacokinetic Interaction

Metabolism

A

Common metabolic path:

Intestines => portal circulation => liver => modified

  • Oxidation
  • Reduction
  • Hydrolysis
  • Inactivated

Most become water soluble and exreted renally

Tolerance

  • Inc activity of microsomal enzymes to speed metabolism of drug
34
Q

Hallmark drug that increases metabolism

A

Phenobarbital

Pull blood and do therapeutic drug monitoring

35
Q

Keppra

A

Leviteracetum

When you add on Keppra to long-term phenobarb user need to give 30 % higher dose of Keppra

36
Q

Metabolism

Inducers

Inhibitors

Metabolites

A

Inducers: decrease duration/potency of other drugs

  • Phenobarbital
  • Rifampin

Inhibitors: Increase duration/ potency of other drugs

  • Cimetidine
  • Chloramphenicol
  • Ketoconazole

Metabolites

  • Diazepam
  • Ketamine
  • Morphine
37
Q

Pharmacokinetic Interaction

Elimination

A

Renal

  • Competition for same renal tubular transport system
  • Alter urinary pH (ion trapping)
  • Alter renal blood flow

Biliary

  • Enterohepatic recirculation
    • Antibiotics alter (clindamycin)

Respiratory

38
Q

Post op drug that changes blood flow to kidneys via prostaglandins

A

NSAIDs

39
Q

Considerations for treating Endocrinopathies

A

Treatments usually require enterohepatic recirculation

Antibiotics can alter gut flora and affect the enterohepatic recirculation

40
Q

Decrease in respiratory drive

A

All Opioids

Slows respiratory elimination

41
Q

Aspirin and phenobarb

A

Increase elimination if given with Ammonium-chloride

Decrease elimination if given with Sodium bicarb

42
Q

Drugs that compete for renal excretion

Acidic Drugs

A

Acidic Drugs

  • Penicillins
  • Cephalosporins
  • Sulfonamids (TMS)
  • Furosemide
  • NSAIDS
43
Q

Drugs that compete for renal excretion

Basic Drugs

A

Basic Drugs

  • Procainamide
  • Dopamine
  • Trimethoprim
  • Opioids
44
Q

Pharmacodynamic Interaction

1.

2.

3.

A
  1. Pharmacological
    * Act on same receptor
  2. Physiological
    * Act on different recptors that regulate a common process
  3. Elicit effects that aren’t receptor mediated but have final comon pathway
45
Q

Pharmacodynamic Drug Interactions

Synergistic

A

Synergistic

  • CNS depressants
    • phenobarb + diazepam
  • Autonomic drugs
    • …..
  • Beta blockers + Ca2+ blockers
    • bradycardia
  • NSAIDS + steroids
    • ulcers
  • Aminoglycosides + amphotericin B
    • kidneys
46
Q

Pharmacodynamic Drug Interactions

Antagonistic

A

Antagonistic

  • Alcohol + caffeine
  • Anticoagulants + phytonadione (vitamin K)
  • Furosemide + digoxin
47
Q

Warfarin

A

Anticoagulant

Negated by vitamin K

Dogs that eat……put on Vitamin K for for weeks

48
Q

Drug Interaction and electrolyte changes

Hypokalemia

Hyperkalemia

A

Decreased K when diuretics (furosemide) given w/

  • digitalis
  • antiarrhythmias
  • muscle relaxants

Hypokalemia: increased digitalis binding to Na/K ATPase

  • Toxicity

Hyperkalemia: decreased digitalis binding to Na/K ATPase

  • Decreased efficacy
49
Q

Digoxin other drug interactions

A
  1. Quinidine (Class 1A)
  • competes for same receptor
  • Dec renal clearance of digoxin (higher therapeutic drug conc)
  1. Diuretics
  • worry about hypokalemia
  • can use potassium sparing diuretic
  1. Hypercalcemia
  • induces inc in Intracellular calcium
  • enhances digitalis
  1. Hypomagnesemic patient
    * more likely to cause an arrhythmia on digoxin
50
Q

Preventing Drug interactions

A
  1. Avoid polypharmacy
  2. Assess and plan treatment regimen
  3. Compatibility assessment
    * especially with metal ions
  4. Color code IV lines
  5. Multilumen catheters
  6. In-line filters
51
Q

Drug effects on lab tests

A
  1. Steroids
    * inc ALP (dogs)
  2. Potassium bromide
  • Pseudohyperchloridemia
  • Machine reads bromides as chlorides
  1. Phenobarbital
  • Inc liver enzymes
  • neutropenia (can cause bone marrow necrosis)
  1. Acetominophen, methimazole, methylene blue
    * methemoglobinemia (esp cats)
  2. Chemotherapy, estrogens, griseofulvin, phenylbutazone
    * bone marrow supression
  3. NSAIDS
    * platelet dysfunction
52
Q

Drug interactions can start

A

Prior to administration

53
Q

In vivo drug interactions are…

A

Hard to predict or diagnose

54
Q

three types of drug interactions

A
  1. Incompatibilities
  2. PK
  3. PD
55
Q

PK interactions

Absorption

Phenobarb and Griseofulvin

A

Diminished absorption of griseofulvin in animals treated with phenobarb

56
Q

Altered drug absorption in presence of food

Inc

Dec

A

Inc:

  • Chlorothiazide
  • Diazepam
  • Phenytoin

Dec:

  • Amoxicillin
  • Tetracyclin
  • Aspirin
57
Q

Drugs that are highly protein bound

A

Erythromycin

Phenylbutazone

Thiopental

58
Q

Excretion and alteration of urinary pH

A

Drugs that alter urinary pH

  • may alter urinary excretion of ionizable drugs by ion trapping
59
Q

Lidocaine for

A

ventricular arrhythmias