Copyright remains in the Author’s name. The work is licensed under a Creative Commons Attribution - Noncommercial Works License. Authors are required to complete and sign an Author Agreement form that outlines Author and Publisher rights and terms of publication. The Agreement form should be uploaded along with other submissions files and any submission will be considered incomplete without it [forthcoming].
Material submitted for publication in the SAMJ is accepted provided it has not been published or submitted for publication elsewhere. Please inform the editorial team if the main findings of your paper have been presented at a conference and published in abstract form, to avoid copyright infringement. The SAMJ does not hold itself responsible for statements made by the authors.
Previously published images
If an image/figure has been previously published, permission to reproduce or alter it must be obtained by the authors from the original publisher and the figure legend must give full credit to the original source. This credit should be accompanied by a letter indicating that permission to reproduce the image has been granted to the author/s. This letter should be uploaded as a supplementary file during submission.
Author Biographies
ESW Jones
Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
M Lesosky
Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
M Blockman
Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
S Castel
Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
EH Decloedt
Department of Medicine, Tygerberg Hospital and Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
SLU Schwager
Department of Integrative Biomedical Sciences, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
ED Sturrock
Department of Integrative Biomedical Sciences, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
L Wiesner
Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
BL Rayner
Department of Medicine, Groote Schuur Hospital and Faculty of Health Sciences, University of Cape Town, South Africa
Main Article Content
Therapeutic drug monitoring of amlodipine and the Z-FHL/HHL ratio: Adherence tools in patients referred for apparent treatment-resistant hypertension
ESW Jones
M Lesosky
M Blockman
S Castel
EH Decloedt
SLU Schwager
ED Sturrock
L Wiesner
BL Rayner
Abstract
Background. Non-adherence to antihypertensives is a cause of ‘pseudo-treatment-resistant’ hypertension. Objective. To determine whether monitoring plasma amlodipine concentrations and inhibition of angiotensin-converting enzyme (ACE) can be adjunct adherence tools. Methods. Patients with hypertension who were prescribed enalapril and amlodipine were enrolled. Blood pressures (BPs) were monitored and an adherence questionnaire was completed. Steady-state amlodipine was assayed using liquid chromatography-mass spectrometry and degree of ACE inhibition using the Z-FHL/HHL (z-phenylalanine-histidine-leucine/hippuryl-histidine-leucine) ratio. Results. One hundred patients (mean (standard deviation) age 50.5 (12) years, 46% male) were enrolled. Based on plasma assays, 26/97 patients (26.8%) were unsuppressed by enalapril and 20/100 (20%) were sub-therapeutic for amlodipine. There were significant BP differences based on plasma levels of the medication: 21/20 mmHg lower in the group with suppressed ACE and 26/20 mmHg in the group with steady-state amlodipine concentrations. Conclusions. Monitoring antihypertensive adherence by assaying plasma medication concentrations is a feasible option for evaluating true v. pseudo-resistant hypertension.
S Afr Med J 2017;107(10):887-891
Donate
AJOL is a Non Profit Organisation that cannot function without donations.
AJOL and the millions of African and international researchers who rely on our free services are deeply grateful for your contribution.
AJOL is annually audited and was also independently assessed in 2019 by E&Y.
Your donation is guaranteed to directly contribute to Africans sharing their research output with a global readership.
Once off donations here:
For annual AJOL Supporter contributions, please view our Supporters page.
Tell us what you think and showcase the impact of your research!
Please take 5 minutes to contribute to our survey so that we can better understand the contribution that African research makes to global and African development challenges. Share your feedback to help us make sure that AJOL's services support and amplify the voices of researchers like you.