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All oral treatment likely to be sustained/modified release, usually given twice-daily. Peak expected conc after 4-6 hours (after approx.4- 5 days to reach steady-state) so best time for ? toxicity.
If worrying about under-treatment may consider trough, most consistent being pre-dose (since probably taking treatment at 8-9 am/pm then need to take early in the morning having withheld dose until sampling, or possibly at 5-6 pm).
Would also welcome evidence for annual testing in stable patients.
Best wishes
Nigel
Dr Nigel Capps
Consultant Chemical Pathologist
Director of Research and Development
The Shrewsbury and Telford Hospital NHS Trust
Joint Cardiovascular Speciality Group Lead, NIHR Clinical Research Network: West Midlands
Chairman of the Medical, Scientific & Research Committee, HEART UK (the Cholesterol Charity)
Princess Royal Hospital
Apley Castle
TelforD
TF1 6TF
Phone 01952 641222 x 4311
Fax 01952 641804
From: Clinical biochemistry discussion list [mailto:[log in to unmask]] On Behalf Of Jonathan Kay
Sent: 14 May 2014 15:13
To: [log in to unmask]
Subject: Re: Time of sampling for theophylline measurement
After a quick search I can see that others are recommending annual measurements or something similar.
I'd be interested in the evidence around this.
What does NICE say?
Thanks
Jonathan
On 14 May 2014, at 14:46, Julian Barth <[log in to unmask]> wrote:
Emma
By co-incidence we have been discussing this with pharmacy. In West Yorks it is believed that all preparations of theophylline are given as sustained release preparations so there is wisdom in taking 6-10 hours post dose samples as toxicity is related to peak concentrations.
Our involvement was triggered by pharmacy recommending annual plasma measurements and I was asking for the evidence for this blanket recommendation! but not been given it yet.
BW
Julian
Julian H Barth
Chair, Clinical Reference Group for Obesity, NHS England
Consultant Chemical Pathologist
Leeds General Infirmary
Leeds LS1 3EX
tel 0113 392 3607
fax 0113 392 5174
>>> "Ashley Emma (KINGSTON HOSPITAL NHS FOUNDATION TRUST)" <[log in to unmask]> 14 May 2014 11:05 >>>
Dear all,
We've had a query from one of our clinicians regarding sampling timing for oral theophylline. Our local guidelines state that levels should be taken immediately pre-dose. However the BNF and the product literature state that it should be taken 4-6 hours post dose. Is this because by 4-6 hours post dose, trough levels are reached? Which is the recommended time to measure?
Any advice would be greatly appreciated.
Many thanks,
Emma
Emma Ashley
Senior Clinical Biochemist
Kingston Hospital NHS Foundation Trust
Galsworthy Road
Kingston upon Thames
Surrey KT2 7QB
Tel. 020 8934 3309
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