Simultaneous LC-MS/MS quantification of oxycodone, tramadol and fentanyl and their metabolites (noroxycodone, oxymorphone, O- desmethyltramadol, N- desmethyltramadol, and norfentanyl) in human plasma and whole blood collected via venepuncture and volumetric absorptive micro sampling

INTRODUCTION

A range of opioids are commonly prescribed to manage chronic pain, but individual patient responses vary greatly, especially in older populations. One source of that variability are differences in absorption, metabolism and excretion, i.e. pharmacokinetics. Blood, plasma and serum concentrations of opioids allow that variability to be quantified and may be used to optimise opioid dosing. As an aid to that process, there is an unmet need to rapidly quantify several opioids and their metabolites in a single analytical method.

AIMS

To develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of tramadol, oxycodone, fentanyl and their major metabolites in various human matrices.

METHODS

Sample preparation involved adding three deuterated internal standards followed by protein precipitation with 100 % acetonitrile, evaporation and reconstitution. Separation of analytes via LC was achieved on a reversed phase column via binary gradient elution using 0.005 % formic acid in water and 100 % acetonitrile as mobile phases. Analytes were detected via MS/MS with multiple reaction monitoring (MRM).

RESULTS

The method was accurate with the inter-day and intra-day accuracy of quality control samples (QCs) below 15 %. It was also precise with inter-day and intra-day coefficient of variation below 15 %. The lower limit of quantification (LLOQ) was 0.2 ng/mL for all analytes except tramadol and its metabolites, where the LLOQ was 10 ng/mL. Recovery was greater than 88 % for all analytes, except for O-desmethyltramadol (81 %). Analytes were stable over four freeze-thaw cycles, for 24 h on the bench top and for 24 h post-preparation. The inter- and intra-day variability of concentrations determined in blood and plasma were within 84-124%, whereas the inter- and intra-day variability for blood samples prepared using volumetric absorptive micro-sampling (VAMS) compared to those prepared from whole blood ranged between 83-122%.

CONCLUSION

A LC-MS/MS method is described that is able to accurately and precisely quantify a number of commonly prescribed opioids and their major metabolites in plasma and whole blood, including whole blood collected using VAMS.

The Risk of Drug-Drug Interactions with Paracetamol in a Population of Hospitalized Geriatric Patients

Aims

This study investigates the consumption of paracetamol and the risk of potential drug-drug interactions and assesses the clinical impact hereof in patients admitted to a department of geriatric medicine.

Methods

A retrospective and longitudinal study was conducted in patients who had been receiving paracetamol upon or during hospitalization. The hospital files of the included patients were reviewed, including documentation of concomitant medications, diagnoses, biochemical values, and adverse incidents during admission. These parameters were used as a clinical follow-up when assessing a clinical probability impact of the identified drug-drug interactions.

Results

In total, 104 patients were admitted during the study period. 91 (87.5%) of these (mean age 86 years) received a prescription or were treated with paracetamol. Of these, 10% were evaluated as being at risk of potential drug-drug interactions with paracetamol. Seven of the potential drug-drug interactions were related to treatments with warfarin, one with valsartan and one with phenytoin. Of the nine patients at risk, six did experience either abnormal biochemical values or potential related clinical incidents. Four patients experienced increased INR (range 3.2–4.6), of which one patient suffered from anaemia and one with hematemesis. Two patients experienced increased ALAT/ASAT (55/42 U/I and 87/51 U/I, both females). One experienced hypertension.

Conclusion

A large majority of the patients in this study received treatment with paracetamol. Six patients were evaluated as having abnormal biochemical values or were experiencing clinical incidents during their hospitalization potentially related to the identified potential drug-drug interactions.

The prevalence of uncontrolled pain in long-term care: a pilot study examining outcomes of pain management processes

Pain in long-term care (LTC) is common among older residents despite the vast options available for optimal pain management. Inadequate pain management affects individual health care outcomes. Researcher evidence has shown that nurse practitioners (NPs) improve the quality of care in LTC but are challenged by multiple barriers that inhibit optimal pain control. The purpose of the current pilot study was to explore both the pain management processes used by nurses in LTC and the documented patient outcomes that come from these processes. In addition, factors were identified that may impact the NP role in providing adequate pain control in LTC. This descriptive study used a retrospective, case-controlled research design that incorporated reviewing 55 LTC resident medical records. Results show how the process of pain management in LTC can be improved by expanding the professional role of the NP.

Pain reporting, opiate dosing, and the adverse effects of opiates after hip or knee replacement in patients 60 years old or older

Our goal was to determine whether there were age-related differences in pain, opiate use, and opiate side effects after total hip or knee arthroplasty in patients 60 years old or older. We hypothesized that there would be no significant differences between age groups in (1) mean pain score, (2) opiate use after adjusting for pain, or (3) opiate side effects after adjusting for opiate use and pain score. We retrospectively reviewed the electronic and paper charts of all patients undergoing total joint replacements at our institution over 3 years who met the following criteria: (1) 60 years old or older, (2) primary single total knee or total hip replacement, and (3) no preoperative dementia. Preoperative, intraoperative, and postoperative course data were collected using a customized data entry process and database. We divided the patients into 2 age groups, those 60 to 79 years old and those 80 years old or older. Using a marginal model with the panel variable of postoperative day, we investigated the associations between age group and pain, age group and pain adjusting for opiate use, and age group and complications (respiratory depression, naloxone usage as a measure of respiratory arrest, delirium, constipation, and urinary retention) adjusting for opiate use (Xtgee, Stata10, Stata Corp. LP, College Station, Texas). Significance was set at P < .05. We found no significant difference in pain scores between groups, but the older group had significantly fewer opiates prescribed yet significantly more side effects, including delirium (odds ratio 4.2), than did the younger group, even after adjusting for opiate dose and pain score.