In this study, four different chromatographic column chemistries (octadecylsilane/ C18, pentafluorophenyl/ PFP, octadecylated polystyrene-divinylbenzene/ PRP and underivatized silica/ HILIC) were compared under optimal conditions to evaluate the relative strengths and weaknesses of the phases for use in the determination of pain management drugs by LC-MS. Furthermore, different column scaffoldings, traditional silica, porous shell, and porous polymer, were also compared. The drugs included in this study included buprenorphine, fentanyl, methadone, naloxone, oxycodone, and tramadol. Factors such as peak area, peak resolution, theoretical plates, and reproducibility were compared among the columns and analytes using a 2-way analysis of variance (ANOVA). Because of the lipophilic nature of these drugs, the C18 columns tended to offer the best performance; however, PFP and PRP columns were viable alternatives. Finally, HILIC separation was also suitable for most of the compounds under study; often providing higher peak areas (sensitivity) likely associated with higher organic (% B) conditions, thus favoring mass spectrometric detection. To our knowledge, this is the first study to explore viability of other non-C18 stationary phases such as PRP and HILIC for this drug class.

Opioid use during pregnancy can result in the newborn being physically dependent on the substance, thus experiencing drug withdrawal, termed neonatal abstinence syndrome (NAS). Buprenorphine and methadone are two drugs used to treat opioid withdrawal and are approved for use in pregnancy. Quantification of these compounds in umbilical cord plasma would help assess in utero exposure of neonates in cases of buprenorphine or methadone use during pregnancy. An LC-MS/MS method using solid-phase extraction sample preparation was developed and validated for the simultaneous quantification of methadone, buprenorphine, norbuprenorphine, and glucuronide metabolites in umbilical cord plasma. The average accuracy (percentage error) and precision (relative standard deviation) were

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Abstract available in the American Journal of Pharmaceutical Education.

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Abstract available in the Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy.

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Purpose: Neuromuscular blocking agents are a common cause of hypersensitivity reactions during surgery. An allergy evaluation, including skin testing of these drugs prior to future surgeries, may help prevent life threatening reactions. Drug concentrations utilized for skin testing vary by country and institution. The purpose of this study was to investigate the stored stability of clinically relevant dilutions of neuromuscular blocking agents (NMBAs), namely succinylcholine, atracurium, cisatracurium, rocuronium, pancuronium, and vecuronium, for skin prick/intradermal testing. Methods: Concentrations of NMBAs were monitored by liquid chromatography-mass spectrometry (LC-MS/MS) for a period of 14 days. Dilutions of NMBAs were prepared in saline by factors of 10x, 100x, 1,000x, 10,000x, and 100,000x, as sensitivity of the assay allowed. Diluted drug products were stored in a laboratory refrigerator until sampling. On sampling days, aliquots of each dilution were removed for analysis, and compared to a freshly prepared set of reference dilutions. Results: Acceptable potency of the stored preparations is defined as 90-110% of the initial drug concentration (versus a reference). All drugs were stable for at least 48 hours in the 1:10 dilution and for 24 hours in the 1:100 dilution. At higher dilution factors, the detectable amount of drug in the stored dilutions deteriorated rapidly, indicating that such preparations should be used immediately. Conclusion: With increasing dilution factors, the stability of these drugs in saline decreases, increasing deviation between samples and references. The most stable dilutions for each of the drugs tested were 10x and 100x.