Drug–Nutrient Interactions
10
Srinivas Guptha Gunturu and T.S. Dharmarajan
Questions and Answers
1. DNIs in the geriatric age group are not influenced by:
A. Polypharmacy
B. Reduced homeostatic mechanisms
C. Age-related physiological changes in renal and hepatic
function
D. Form of medication administration: liquid, tablet, or
capsule
Answer: D
Explanation: Several factors render older adults prone to
DNIs: polypharmacy, comorbidities, age-related changes
in pharmacokinetics and pharmacodynamics, malnutrition,
interindividual variability, and reduced homeostatic mechanisms [12, 13]. Geriatric patients are also more prone to
altered pharmacokinetics and dynamics by virtue of a difference in their body fat (increased from 20 to 40%), lean
body mass (decreased from 10 to 15%) [11], and altered
renal and hepatic functions.
Reduced homeostatic reserves are a result of decline in
functions of the kidney, liver, and heart and other systems
with age. The form of medication (liquid, solid, or capsule) does not influence the occurrence of nutrient interactions in the geriatric age group.
2. Which one of the following statements is true of DNIs?
A. Precipitant agent causes the interaction
B. Object agent causes the interaction
C. DNIs usually result in nullifying the drug benefit
D. DNIs usually result in amplifying the drug benefit
Answer: A
Explanation: In a DNI, a “precipitant agent” causes the
interaction and an “object agent” is the one affected. DNIs
need not always result in negative effects. For example
grape fruit juice (GPJ) can increase bioavailability of calcium channel blockers and enhance their antihypertensive
effects. Green leafy vegetable nullify the warfarin effect
through their vitamin K content. Phenytoin causes vitamin D deficiency by increasing the inactivation. However
DNIs do not always result in amplifying or nullifying the
drug benefit; the effect may be none, or it may nullify or
amplify the drug or nutrient benefit.
3. GPJ inhibits which of the following?
A. Cytochrome P450 isoenzymes
B. 11B-hydroxysteroid dehydrogenase
C. OATP-A and P-glycoprotein efflux transporter proteins
D. All of the above
Answer: D
Explanation: GPJ inhibits intestinal cytochrome P450
isoenzymes, 11B-hydroxysteroid dehydrogenase, OATP-A
transporter protein, and P-glycoprotein efflux transporter
protein, thereby increasing bioavailability of nicardipine,
nimodipine, nislodipine, felodipine, diazepam, midazolam, erythromycin, lovastatin, simvastatin, sildenafil, buspirone, atorvastatin, sertraline, budesonide, and colchicine.
GPJ has an effect on the intestinal enzymes and does not
affect hepatic enzymes.
4. Increased warfarin effect and risk if bleeding is not noticed
with which of the following?
A. Garlic
B. Ginger
C. Ginkgo biloba
D. GPJ
Answer: D
Explanation: Garlic, ginger, ginkgo, and feverfew inhibit
platelet aggregation and prolong bleeding tendency.
Garlic inhibits platelet activating factor and thereby platelet plug formation [102]. The effect of ginseng is controversial in literature; a decreased anticoagulant effect and
increased thrombotic tendency has been described.
Decrease in warfarin plasma levels and anticoagulant
effect is noted with SJW. Saw palmetto, a berry extract
used for treatment of benign prostatic hyperplasia potenti-
C.S. Pitchumoni and T.S. Dharmarajan (eds.), Geriatric Gastroenterology,
DOI 10.1007/978-1-4419-1623-5_10, © Springer Science+Business Media, LLC 2012
91
92
S.G. Gunturu and T.S. Dharmarajan
ates anticoagulant effect of warfarin (and bleeding from
NSAIDs). It is essential to screen patients for the use of
these supplements when the patient is on warfarin and for
unexplained alterations in INR. All herbals must be discontinued at least a week prior to surgery to prevent bleeding or clotting consequences. Interestingly, GPJ does not
influence warfarin kinetics.
5. Which single answer best describes long-term alcohol use
and folate depletion?
A. Malabsorption of folic acid
B. Interference with the enterohepatic circulation
C. Increased breakdown and excretion of folate
D. Multiple mechanisms, including all the above
Answer: D
Explanation: Long-term alcohol use not only decreases
the quality and quantity of food intake but also results in
malabsorption secondary to other causes. These include
interruption of the brush border membrane and folate
kinetics, possible disruption of the enterohepatic circulation,
interference of folate metabolism, acceleration of folate
breakdown and its increased renal excretion. While one
specific basis may be largely applicable in a given person,
it is likely that it is multifactorial.
6. Which of the following choices is not a well-known risk
for predisposition to osteoporosis following chronic use?
A. Proton pump inhibitors
B. Coffee
C. Heparin
D. Tea
Answer: D
Explanation: Long-term and excessive use of caffeine, proton pump inhibitors (PPIs), heparin, and warfarin can lead
to osteoporosis. Caffeine in large amounts (over 300 mg
per day) inhibits osteoblast formation and vitamin D receptor expression, decreasing new bone formation leading to
osteoporosis; caffeine also causes renal loss of calcium.
However, tea may actually offer a protective action through
its flavonoids. Warfarin inhibits gamma-carboxylation of
glutamate and incorporation into bone mass predisposing
to osteoporosis. Chronic PPI therapy leads to osteoporosis,
through acid suppression in the stomach; antiosteoporotic
measures may be indicated in these patients. Heparin
decreases bone formation and increases bone resorption by
inhibiting osteoprotegerin expression in bone. While tea
contains caffeine, tea may have a protective effect through
ingredients such as flavonoids.
7. A 70-year-old male is on simvastatin, nicardipine and
furosemide. He loves GPJ and consumes a glass (250 mL)
daily, even more on weekends. Which single statement
would be your recommendation to the patient?
A. Stop GPJ consumption completely because of drug
interaction.
B. Consume GPJ separately from medications to decrease
any effect on the drugs.
C. Do not change the present intake, as GPJ is good
for health.
D. Do not forbid GPJ, but suggest amounts of less than
250 mL daily, with regularity to time and amount of
consumption. Continue to take medications regularly
as recommended.
Answer: D
Explanation: GPJ inhibits the cytochrome P450 (CYP)
system in the gut; when ingested in reasonable amounts,
the gut CYP system stays inhibited for about 24 h; the
timing of medication intake has little relevance to the drug
interaction with GPJ. It is generally a good practice to be
regular in lifestyle activities; this applies to the timing of
meals, amount of GPJ ingested daily and medication
intake with reference to timing and relation to food intake.
The patient should attempt to maintain the quantity of
GPJ ingested reasonable; perhaps less than 250 mL daily,
as larger amounts inhibit the CYP system for longer periods, with the timing of intake to be fairly regular. Larger
amounts ingested periodically may lead to fluctuations in
enzyme inhibition or longer periods of inhibition and consequent erratic drug levels.
8. A 70-year-old female with no significant comorbidities and
a body mass index of 24 expresses her love for caffeinated
beverages; which single answer best describes a higher
likelihood of developing osteoporosis in this individual?
A. Coffee consumption, over four cups daily
B Tea consumption, three cups daily
C. Both tea and coffee consumption
D. Neither tea nor coffee consumption
Answer: A
Explanation: In a study, 1,222 of the 1,689 eligible homedwelling women aged 70–73 years were observed for
lifestyle, including the following; data on long occupational and leisure time physical activity, calcium intake,
smoking habits, alcohol intake, and medical history were
obtained by a self-completed questionnaire and their bone
mineral density measured once. The women with body
mass index less than 25.1 had lower radial bone mineral
10 Drug–Nutrient Interactions
density (BMD) values (p < 0.0001), if the patients consumed over four cups of coffee per day (see conclusions)
(RR 1.7; 1.1–2.7). Caffeine ingestion causes an acute calcium excretion in the urine, but this is not sustained for
24 h periods. The effect of caffeine induced urinary calcium loss can be partially offset by drinking a glass of
93
milk for each cup of coffee consumed. Although tea contains caffeine, its other components such as flavonoids
may influence BMD and protect against osteoporosis in
older women. The effect of habitual tea drinking on bone
density is small and does not significantly alter fracture
risk in postmenopausal women.