Clinical use
Therapeutic drug monitoring of meropenem. This may be of value in patients with difficult infections, continuous infusion, and/or impaired renal function.
Background
Therapeutic drug monitoring is the measurement of specific drug concentrations in the blood at timed intervals, in order to maintain a relatively constant concentration of the medication in the circulation. Monitored drugs tend to have a narrow “therapeutic index” – the difference between the toxic and therapeutic doses of medications. For some drugs, maintaining this steady concentration in the blood cannot be achieved by simply giving a standard dose of medication to everyone. Each person will absorb, metabolise, utilise, and eliminate drugs at different rates based upon their age, general state of health, genetic makeup, and the influence of other medications that they are taking. These factors may change over time and vary from day to day or with various disease states.
Therapeutic drug monitoring (TDM) aims to optimise individual dosage regimens, enabling the assessment of safety and efficacy of certain drugs. Current TDM approaches include measuring drug serum concentration together with appropriate medical interpretation.
Candidate drugs for TDM possess one or more of the following: narrow therapeutic range, high pharmacokinetic (PK) variability and a clear relationship between serum concentration and therapeutic response. TDM is also helpful for the drug optimisation in patients with renal, hepatic or gastrointestinal insufficiency.
Reference ranges
There are too many dose regimens used to give single guideline ranges for this particular assay and interpretations of levels needs to be patient specific. The MIC and the organism are required for result interpretation.
Patient preparation
Reference laboratory recommendation: please send a pre dose sample and a post dose sample, taken 1 hour after the end of IV administration.
Specimen requirements
- Gold top serum separator tube
- Approx. 1-2 mL of separated serum (minimum acceptable is 100µL)
Minimum volume
100µL
Limitations & restrictions
Samples should NOT be sent by post since the drug is liable to degradation, send by courier, frozen or on ice.
Turnaround time
<3 days from receipt at the reference laboratory.
Analysing laboratory
Antimicrobial Reference Laboratory, Level 2, Phase 1, Pathology Sciences Building, Southmead Hospital, Westbury-on-Trym, Bristol, BS10 5NB
Additional information
The reference laboratory requires notification one day in advance of sending a sample for meropenem assay. Please notify Microbiology, James Cook University Hospital one day prior to taking and sending the sample to the laboratory.
Please visit the guidance page for the Antimicrobial Reference Laboratory for more information.