Iron supplements in nursing home patients associated with reduced carbamazepine absorption

Jae Eun Ahn, Sai Praneeth Reddy Bathena, Richard Brundage, Jeannine M Conway, Ilo E Leppik, Angela K Birnbaum

Research output: Contribution to journalArticle

Abstract

Persons in nursing homes receive a number of medications that may interfere with the pharmacokinetics of carbamazepine (CBZ). The aim of our study was to determine factors that may affect the pharmacokinetics of CBZ in elderly nursing home patients. Methods: CBZ concentration data collected from 60 nursing homes across the US were evaluated. Inclusion criteria included residency in a nursing home for at least 2 months, age 65 years or older, a stable dosing regimen of CBZ for at least 4 weeks (considered steady state), available CBZ concentration, and complete information regarding all co-medications. Using a nonlinear mixed-effects model, the data were adequately described by a one-compartment model with first-order absorption and elimination. Goodness-of-fit plots, plausibility of parameter estimates, visual predictive check and nonparametric bootstrap were used to evaluate the models. Main findings: The final data set consisted of 345 CBZ concentrations from 99 subjects (38 males, 61 females). The population estimate of apparent clearance (CL/F) for a 70-kg person was 3.69 L/hr (RSE 6.9%). Residents were receiving either immediate (93.9%) or extended release (6.1%) formulation of CBZ and the K a of each formulation was fixed to literature values. Age, sex, and co-medications had no effect on CL/F and apparent volume of distribution. Iron supplementation, which was taken by 16% of the residents, resulted in a 33% decrease in bioavailability (p < 0.001). No other medications were found to have an effect. Conclusions: Results from this pharmacokinetic study indicate that use of iron supplementation is associated with a reduction in absorption of CBZ and may need to be considered when dosing CBZ in patients taking iron supplementation.

Original languageEnglish (US)
Pages (from-to)115-118
Number of pages4
JournalEpilepsy Research
Volume147
DOIs
StatePublished - Nov 1 2018

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Carbamazepine
Nursing Homes
Iron
Pharmacokinetics
Internship and Residency
Biological Availability

Keywords

  • Carbamazepine
  • Iron supplements
  • Nursing home elderly
  • Pharmacokinetics

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

Cite this

Iron supplements in nursing home patients associated with reduced carbamazepine absorption. / Ahn, Jae Eun; Bathena, Sai Praneeth Reddy; Brundage, Richard; Conway, Jeannine M; Leppik, Ilo E; Birnbaum, Angela K.

In: Epilepsy Research, Vol. 147, 01.11.2018, p. 115-118.

Research output: Contribution to journalArticle

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abstract = "Persons in nursing homes receive a number of medications that may interfere with the pharmacokinetics of carbamazepine (CBZ). The aim of our study was to determine factors that may affect the pharmacokinetics of CBZ in elderly nursing home patients. Methods: CBZ concentration data collected from 60 nursing homes across the US were evaluated. Inclusion criteria included residency in a nursing home for at least 2 months, age 65 years or older, a stable dosing regimen of CBZ for at least 4 weeks (considered steady state), available CBZ concentration, and complete information regarding all co-medications. Using a nonlinear mixed-effects model, the data were adequately described by a one-compartment model with first-order absorption and elimination. Goodness-of-fit plots, plausibility of parameter estimates, visual predictive check and nonparametric bootstrap were used to evaluate the models. Main findings: The final data set consisted of 345 CBZ concentrations from 99 subjects (38 males, 61 females). The population estimate of apparent clearance (CL/F) for a 70-kg person was 3.69 L/hr (RSE 6.9{\%}). Residents were receiving either immediate (93.9{\%}) or extended release (6.1{\%}) formulation of CBZ and the K a of each formulation was fixed to literature values. Age, sex, and co-medications had no effect on CL/F and apparent volume of distribution. Iron supplementation, which was taken by 16{\%} of the residents, resulted in a 33{\%} decrease in bioavailability (p < 0.001). No other medications were found to have an effect. Conclusions: Results from this pharmacokinetic study indicate that use of iron supplementation is associated with a reduction in absorption of CBZ and may need to be considered when dosing CBZ in patients taking iron supplementation.",
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AU - Brundage, Richard

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AU - Leppik, Ilo E

AU - Birnbaum, Angela K

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AB - Persons in nursing homes receive a number of medications that may interfere with the pharmacokinetics of carbamazepine (CBZ). The aim of our study was to determine factors that may affect the pharmacokinetics of CBZ in elderly nursing home patients. Methods: CBZ concentration data collected from 60 nursing homes across the US were evaluated. Inclusion criteria included residency in a nursing home for at least 2 months, age 65 years or older, a stable dosing regimen of CBZ for at least 4 weeks (considered steady state), available CBZ concentration, and complete information regarding all co-medications. Using a nonlinear mixed-effects model, the data were adequately described by a one-compartment model with first-order absorption and elimination. Goodness-of-fit plots, plausibility of parameter estimates, visual predictive check and nonparametric bootstrap were used to evaluate the models. Main findings: The final data set consisted of 345 CBZ concentrations from 99 subjects (38 males, 61 females). The population estimate of apparent clearance (CL/F) for a 70-kg person was 3.69 L/hr (RSE 6.9%). Residents were receiving either immediate (93.9%) or extended release (6.1%) formulation of CBZ and the K a of each formulation was fixed to literature values. Age, sex, and co-medications had no effect on CL/F and apparent volume of distribution. Iron supplementation, which was taken by 16% of the residents, resulted in a 33% decrease in bioavailability (p < 0.001). No other medications were found to have an effect. Conclusions: Results from this pharmacokinetic study indicate that use of iron supplementation is associated with a reduction in absorption of CBZ and may need to be considered when dosing CBZ in patients taking iron supplementation.

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