Loratadine and terfenadine interaction with nefazodone: Both antihistamines are associated with QTc prolongation

Darrell R. Abernethy, Jean T. Barbey, John Franc, Karen S. Brown, Irene Feirrera, Neville Ford, Daniel E. Salazar

Research output: Contribution to journalArticle

Abstract

Background and Objective: Nefazodone inhibits CYP3A; therefore coadministration with CYP3A substrates such as terfenadine or loratadine may result in increased exposure to these drugs. A potential pharmacodynamic consequence is electrocardiographic QTc prolongation, which has been associated with torsade de pointes cardiac arrhythmia. Therefore a clinical pharmacokinetic-pharmacodynamic evaluation of this potential interaction was conducted. Methods: A randomized, double-blind, double-dummy, parallel group, multiple-dose design was used. Healthy men and women who were given doses of 60 mg of terfenadine every 12 hours, 20 mg of loratadine once daily, and 300 mg of nefazodone every 12 hours were studied. Descriptive pharmacokinetics (time to maximum concentration, maximum concentration, and area under the plasma concentration-time curve) were used for the examination of interactions among the respective parent drugs and metabolites. QTc prolongation (mean value over the dosing interval) was the pharmacodynamic parameter measured. Kinetic and dynamic analysis was used for the examination of pooled concentration and QTc data with the use of a linear model. Results: Concomitant nefazodone treatment markedly increased the dose interval area under the plasma concentration-time curve of both terfenadine (mean value, 17.3 ± 8.5 ng · mL/h versus 97.4 ± 48.9 ng · mL/h; P <.001) and carboxyterfenadine (mean value, 1.69 ± 0.48 μg · h/mL versus 2.88 ± 0.53 μg · h/mL; P <.001) and moderately increased the dose interval area under the plasma concentration-time curve of both loratadine (mean value, 31.5 ± 27.9 ng · h/mL versus 43.7 ± 25.9 ng · h/mL; P <.014) and descarboethoxyloratadine (mean value, 73.4 ± 54.9 ng · h/mL versus 81.9 ± 26.2 ng · h/mL; P <.002). The mean QTc was unchanged with terfenadine alone; however, it was markedly prolonged with concomitant nefazodone and terfenadine (mean [90% confidence interval] prolongation 42.4 ms [34.2, 50.6 ms]; P <.05). Similarly, the mean QTc was unchanged with loratadine alone; however, it was prolonged with concomitant nefazodone and loratadine (21.6 ms [13.7, 29.4 ms]; P <.05). Nefazodone alone did not change mean QTc. QTc was positively correlated with terfenadine plasma concentration (r 2 = 0.21; P = .0001). Similarly, QTc was positively correlated with loratadine plasma concentration (r 2 = 0.056; P = .0008) but with a flatter slope. There was no relationship between QTc and nefazodone plasma concentration during treatment with nefazodone alone (r 2 = 0.002, not significant). Conclusions: In healthy men and women, concomitant nefazodone treatment at a therapeutic dose increases exposure to both terfenadine and carboxyterfenadine. This increased exposure is associated with marked QTc prolongation, which is correlated with terfenadine plasma concentration. A similar interaction occurs with loratadine, although it is of lesser magnitude. Concomitant administration of nefazodone with terfenadine may have predisposed individuals to the arrhythmia associated with QTc prolongation, torsade de pointes, when terfenadine was available for clinical use. However, a new finding is that in the context of higher than clinically recommended daily doses (20 mg) of loratadine concomitant administration with a metabolic inhibitor such as nefazodone can also result in QTc prolongation.

Original languageEnglish (US)
Pages (from-to)96-103
Number of pages8
JournalClinical Pharmacology and Therapeutics
Volume69
Issue number3
DOIs
StatePublished - 2001
Externally publishedYes

Fingerprint

Loratadine
Terfenadine
Histamine Antagonists
Torsades de Pointes
Cytochrome P-450 CYP3A
Cardiac Arrhythmias
nefazodone
Pharmacokinetics
Therapeutics
Pharmaceutical Preparations
Linear Models

ASJC Scopus subject areas

  • Pharmacology

Cite this

Abernethy, D. R., Barbey, J. T., Franc, J., Brown, K. S., Feirrera, I., Ford, N., & Salazar, D. E. (2001). Loratadine and terfenadine interaction with nefazodone: Both antihistamines are associated with QTc prolongation. Clinical Pharmacology and Therapeutics, 69(3), 96-103. https://doi.org/10.1067/mcp.2001.114230

Loratadine and terfenadine interaction with nefazodone : Both antihistamines are associated with QTc prolongation. / Abernethy, Darrell R.; Barbey, Jean T.; Franc, John; Brown, Karen S.; Feirrera, Irene; Ford, Neville; Salazar, Daniel E.

In: Clinical Pharmacology and Therapeutics, Vol. 69, No. 3, 2001, p. 96-103.

Research output: Contribution to journalArticle

Abernethy, Darrell R. ; Barbey, Jean T. ; Franc, John ; Brown, Karen S. ; Feirrera, Irene ; Ford, Neville ; Salazar, Daniel E. / Loratadine and terfenadine interaction with nefazodone : Both antihistamines are associated with QTc prolongation. In: Clinical Pharmacology and Therapeutics. 2001 ; Vol. 69, No. 3. pp. 96-103.
@article{5d22a41c67874866a43629cb4d295767,
title = "Loratadine and terfenadine interaction with nefazodone: Both antihistamines are associated with QTc prolongation",
abstract = "Background and Objective: Nefazodone inhibits CYP3A; therefore coadministration with CYP3A substrates such as terfenadine or loratadine may result in increased exposure to these drugs. A potential pharmacodynamic consequence is electrocardiographic QTc prolongation, which has been associated with torsade de pointes cardiac arrhythmia. Therefore a clinical pharmacokinetic-pharmacodynamic evaluation of this potential interaction was conducted. Methods: A randomized, double-blind, double-dummy, parallel group, multiple-dose design was used. Healthy men and women who were given doses of 60 mg of terfenadine every 12 hours, 20 mg of loratadine once daily, and 300 mg of nefazodone every 12 hours were studied. Descriptive pharmacokinetics (time to maximum concentration, maximum concentration, and area under the plasma concentration-time curve) were used for the examination of interactions among the respective parent drugs and metabolites. QTc prolongation (mean value over the dosing interval) was the pharmacodynamic parameter measured. Kinetic and dynamic analysis was used for the examination of pooled concentration and QTc data with the use of a linear model. Results: Concomitant nefazodone treatment markedly increased the dose interval area under the plasma concentration-time curve of both terfenadine (mean value, 17.3 ± 8.5 ng · mL/h versus 97.4 ± 48.9 ng · mL/h; P <.001) and carboxyterfenadine (mean value, 1.69 ± 0.48 μg · h/mL versus 2.88 ± 0.53 μg · h/mL; P <.001) and moderately increased the dose interval area under the plasma concentration-time curve of both loratadine (mean value, 31.5 ± 27.9 ng · h/mL versus 43.7 ± 25.9 ng · h/mL; P <.014) and descarboethoxyloratadine (mean value, 73.4 ± 54.9 ng · h/mL versus 81.9 ± 26.2 ng · h/mL; P <.002). The mean QTc was unchanged with terfenadine alone; however, it was markedly prolonged with concomitant nefazodone and terfenadine (mean [90{\%} confidence interval] prolongation 42.4 ms [34.2, 50.6 ms]; P <.05). Similarly, the mean QTc was unchanged with loratadine alone; however, it was prolonged with concomitant nefazodone and loratadine (21.6 ms [13.7, 29.4 ms]; P <.05). Nefazodone alone did not change mean QTc. QTc was positively correlated with terfenadine plasma concentration (r 2 = 0.21; P = .0001). Similarly, QTc was positively correlated with loratadine plasma concentration (r 2 = 0.056; P = .0008) but with a flatter slope. There was no relationship between QTc and nefazodone plasma concentration during treatment with nefazodone alone (r 2 = 0.002, not significant). Conclusions: In healthy men and women, concomitant nefazodone treatment at a therapeutic dose increases exposure to both terfenadine and carboxyterfenadine. This increased exposure is associated with marked QTc prolongation, which is correlated with terfenadine plasma concentration. A similar interaction occurs with loratadine, although it is of lesser magnitude. Concomitant administration of nefazodone with terfenadine may have predisposed individuals to the arrhythmia associated with QTc prolongation, torsade de pointes, when terfenadine was available for clinical use. However, a new finding is that in the context of higher than clinically recommended daily doses (20 mg) of loratadine concomitant administration with a metabolic inhibitor such as nefazodone can also result in QTc prolongation.",
author = "Abernethy, {Darrell R.} and Barbey, {Jean T.} and John Franc and Brown, {Karen S.} and Irene Feirrera and Neville Ford and Salazar, {Daniel E.}",
year = "2001",
doi = "10.1067/mcp.2001.114230",
language = "English (US)",
volume = "69",
pages = "96--103",
journal = "Clinical Pharmacology and Therapeutics",
issn = "0009-9236",
publisher = "Nature Publishing Group",
number = "3",

}

TY - JOUR

T1 - Loratadine and terfenadine interaction with nefazodone

T2 - Both antihistamines are associated with QTc prolongation

AU - Abernethy, Darrell R.

AU - Barbey, Jean T.

AU - Franc, John

AU - Brown, Karen S.

AU - Feirrera, Irene

AU - Ford, Neville

AU - Salazar, Daniel E.

PY - 2001

Y1 - 2001

N2 - Background and Objective: Nefazodone inhibits CYP3A; therefore coadministration with CYP3A substrates such as terfenadine or loratadine may result in increased exposure to these drugs. A potential pharmacodynamic consequence is electrocardiographic QTc prolongation, which has been associated with torsade de pointes cardiac arrhythmia. Therefore a clinical pharmacokinetic-pharmacodynamic evaluation of this potential interaction was conducted. Methods: A randomized, double-blind, double-dummy, parallel group, multiple-dose design was used. Healthy men and women who were given doses of 60 mg of terfenadine every 12 hours, 20 mg of loratadine once daily, and 300 mg of nefazodone every 12 hours were studied. Descriptive pharmacokinetics (time to maximum concentration, maximum concentration, and area under the plasma concentration-time curve) were used for the examination of interactions among the respective parent drugs and metabolites. QTc prolongation (mean value over the dosing interval) was the pharmacodynamic parameter measured. Kinetic and dynamic analysis was used for the examination of pooled concentration and QTc data with the use of a linear model. Results: Concomitant nefazodone treatment markedly increased the dose interval area under the plasma concentration-time curve of both terfenadine (mean value, 17.3 ± 8.5 ng · mL/h versus 97.4 ± 48.9 ng · mL/h; P <.001) and carboxyterfenadine (mean value, 1.69 ± 0.48 μg · h/mL versus 2.88 ± 0.53 μg · h/mL; P <.001) and moderately increased the dose interval area under the plasma concentration-time curve of both loratadine (mean value, 31.5 ± 27.9 ng · h/mL versus 43.7 ± 25.9 ng · h/mL; P <.014) and descarboethoxyloratadine (mean value, 73.4 ± 54.9 ng · h/mL versus 81.9 ± 26.2 ng · h/mL; P <.002). The mean QTc was unchanged with terfenadine alone; however, it was markedly prolonged with concomitant nefazodone and terfenadine (mean [90% confidence interval] prolongation 42.4 ms [34.2, 50.6 ms]; P <.05). Similarly, the mean QTc was unchanged with loratadine alone; however, it was prolonged with concomitant nefazodone and loratadine (21.6 ms [13.7, 29.4 ms]; P <.05). Nefazodone alone did not change mean QTc. QTc was positively correlated with terfenadine plasma concentration (r 2 = 0.21; P = .0001). Similarly, QTc was positively correlated with loratadine plasma concentration (r 2 = 0.056; P = .0008) but with a flatter slope. There was no relationship between QTc and nefazodone plasma concentration during treatment with nefazodone alone (r 2 = 0.002, not significant). Conclusions: In healthy men and women, concomitant nefazodone treatment at a therapeutic dose increases exposure to both terfenadine and carboxyterfenadine. This increased exposure is associated with marked QTc prolongation, which is correlated with terfenadine plasma concentration. A similar interaction occurs with loratadine, although it is of lesser magnitude. Concomitant administration of nefazodone with terfenadine may have predisposed individuals to the arrhythmia associated with QTc prolongation, torsade de pointes, when terfenadine was available for clinical use. However, a new finding is that in the context of higher than clinically recommended daily doses (20 mg) of loratadine concomitant administration with a metabolic inhibitor such as nefazodone can also result in QTc prolongation.

AB - Background and Objective: Nefazodone inhibits CYP3A; therefore coadministration with CYP3A substrates such as terfenadine or loratadine may result in increased exposure to these drugs. A potential pharmacodynamic consequence is electrocardiographic QTc prolongation, which has been associated with torsade de pointes cardiac arrhythmia. Therefore a clinical pharmacokinetic-pharmacodynamic evaluation of this potential interaction was conducted. Methods: A randomized, double-blind, double-dummy, parallel group, multiple-dose design was used. Healthy men and women who were given doses of 60 mg of terfenadine every 12 hours, 20 mg of loratadine once daily, and 300 mg of nefazodone every 12 hours were studied. Descriptive pharmacokinetics (time to maximum concentration, maximum concentration, and area under the plasma concentration-time curve) were used for the examination of interactions among the respective parent drugs and metabolites. QTc prolongation (mean value over the dosing interval) was the pharmacodynamic parameter measured. Kinetic and dynamic analysis was used for the examination of pooled concentration and QTc data with the use of a linear model. Results: Concomitant nefazodone treatment markedly increased the dose interval area under the plasma concentration-time curve of both terfenadine (mean value, 17.3 ± 8.5 ng · mL/h versus 97.4 ± 48.9 ng · mL/h; P <.001) and carboxyterfenadine (mean value, 1.69 ± 0.48 μg · h/mL versus 2.88 ± 0.53 μg · h/mL; P <.001) and moderately increased the dose interval area under the plasma concentration-time curve of both loratadine (mean value, 31.5 ± 27.9 ng · h/mL versus 43.7 ± 25.9 ng · h/mL; P <.014) and descarboethoxyloratadine (mean value, 73.4 ± 54.9 ng · h/mL versus 81.9 ± 26.2 ng · h/mL; P <.002). The mean QTc was unchanged with terfenadine alone; however, it was markedly prolonged with concomitant nefazodone and terfenadine (mean [90% confidence interval] prolongation 42.4 ms [34.2, 50.6 ms]; P <.05). Similarly, the mean QTc was unchanged with loratadine alone; however, it was prolonged with concomitant nefazodone and loratadine (21.6 ms [13.7, 29.4 ms]; P <.05). Nefazodone alone did not change mean QTc. QTc was positively correlated with terfenadine plasma concentration (r 2 = 0.21; P = .0001). Similarly, QTc was positively correlated with loratadine plasma concentration (r 2 = 0.056; P = .0008) but with a flatter slope. There was no relationship between QTc and nefazodone plasma concentration during treatment with nefazodone alone (r 2 = 0.002, not significant). Conclusions: In healthy men and women, concomitant nefazodone treatment at a therapeutic dose increases exposure to both terfenadine and carboxyterfenadine. This increased exposure is associated with marked QTc prolongation, which is correlated with terfenadine plasma concentration. A similar interaction occurs with loratadine, although it is of lesser magnitude. Concomitant administration of nefazodone with terfenadine may have predisposed individuals to the arrhythmia associated with QTc prolongation, torsade de pointes, when terfenadine was available for clinical use. However, a new finding is that in the context of higher than clinically recommended daily doses (20 mg) of loratadine concomitant administration with a metabolic inhibitor such as nefazodone can also result in QTc prolongation.

UR - http://www.scopus.com/inward/record.url?scp=0035107636&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0035107636&partnerID=8YFLogxK

U2 - 10.1067/mcp.2001.114230

DO - 10.1067/mcp.2001.114230

M3 - Article

C2 - 11240972

AN - SCOPUS:0035107636

VL - 69

SP - 96

EP - 103

JO - Clinical Pharmacology and Therapeutics

JF - Clinical Pharmacology and Therapeutics

SN - 0009-9236

IS - 3

ER -