Green HPLC-DAD and HPTLC Methods for Quantitative Determination of Binary Mixture of Pregabalin and Amitriptyline Used for Neuropathic Pain Management.

First analytical methods were herein developed for determination of pregabalin (PGB) and amitriptyline (AMT) as an active binary mixture used for management of neuropathic pain whether in pure forms or in human biological fluids (plasma/urine). First method is green high-performance liquid chromatography-diode array detector (HPLC-DAD) after derivatization of PGB with ninhydrin (NIN) on a reversed-phase C18 column using a mobile phase consisting of ethanol:water (97:3%, v/v) pumped isocratically at 0.8 mL/min; AMT were scanned at 215 nm, whereas PGB-NIN was scanned at 580 nm. Second method is High-performance thin-layer chromatography (HPTLC), where PGB and AMT were separated on silica gel HPTLC F254 plates, using ethanol:ethyl acetate:acetone:ammonia solution (8:2:1:0.05, by volume) as a developing system. AMT peaks were scanned at 220 nm, whereas PGB peaks were visualized by spraying 3% (w/v) ethanolic NIN solution and scanning at 550 nm. Linear calibration curves were obtained for human plasma and urine spiked with PGB and AMT over the ranges of 5-100 µg/mL and 0.2-2.5 µg/band for PGB, and 1-100 µg/mL and 0.1-2.0 µg/band for AMT for HPLC-DAD and HPTLC methods, respectively. The suggested methods were validated according to Food and Drug Administration guidelines for bioanalytical methods validation and they can be applied for routine therapeutic drug monitoring for the concerned drugs.

Ecologically evaluated and FDA-validated HPTLC method for assay of pregabalin and tramadol in human biological fluids.

The introduced research presents a novel in vivo quantitative method for assay of mixtures of pregabalin and tramadol as a common combinations approved for treatment of neuropathic pain. Green analytical chemistry is a recently emerging science concerned with control of the use of chemicals harmful to the environment in various analytical methods. Consequently, a green high-performance thin layer chromatography (HPTLC) method was achieved for determination of the mixture in human plasma and urine satisfying both analytical and environmental standards. The separation was achieved on HPTLC sheets using a separating mixture of ethanol-ethyl acetate-acetone-ammonia solution (8:2:1:0.05, by volume) as a mobile phase. The sheets were dried in air then scanned at two wavelengths. For tramadol, 220 nm was chosen; however, pregabalin is an unconjugated drug, so its determination was a challenge. Hence for pregabalin, the plates were sprayed with ethanolic solution of ninhydrin (3%, w/v), to obtain a conjugated complex, which could be assessed at 550 nm. Furthermore, the developed method fulfilled the US Food and Drug Administration validation guidelines, and proved to be useful in therapeutic drug monitoring of this combination. The Eco-scale assessment protocol was implemented to determine the greenness profile of the applied method.

[On the issue of the detection of pregabalin and lorazepam in the cases of their joint presence for the purpose of chemical toxicological studies]. / Izuchenie pregabalina i lorazepama pri sovmestnom prisutstvii dlia tselei khimiko-toksikologicheskogo issledovaniia.

Data on the detection of joint presence of pregabalin and lorazepam in the biological objects and material evidence. Aim of this study is to develop a method of the detection of pregabalin and lorazepam in urine. The proposed approach to sample preparation of a biological object and the detection of lorazepam and pregabalin allows the detection of toxicants in cases of their joint presence. It can be used in the analysis of urine in cases of acute poisoning for detoxification therapy or chemical toxicological analysis as a preliminary and confirmatory study for the presence of abuse of these drugs.

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Method to Quantify Gabapentin and Pregabalin in Urine.

Gabapentin and pregabalin are anticonvulsant drugs that are also utilized for pain management. A mass spectrometry method was developed and validated to quantify gabapentin and pregabalin in urine to support testing for adherence.

Pregabalin misuse in methadone maintenance treatment patients in Israel: Prevalence and risk factors.

BACKGROUND: Drug users reportedly abuse pregabalin, and its combination with opiates was related to fatalities. We aimed to estimate the prevalence of pregabalin misuse and risk factors among patients in methadone maintenance treatment (MMT). METHODS: A cross-sectional study included all current MMT patients (n = 300) after excluding 9 with prescriptions, from a large tertiary medical center university-affiliated MMT clinic in Israel. Pregabalin was tested in one of the routine urine tests for other substances in December 2017. Data on urine results and patients' characteristics were retrieved from the patients' records. RESULTS: Pregabalin was detected among 53 (17.7%) patients. The group had higher depressive symptoms severity score (21-HAM-D) (11.1 ±â€¯8.4 vs. 8.3 ±â€¯7.8, p = 0.03), a higher prevalence of sero-positive HIV (13.7% vs. 4.2%, p = 0.02), sero-positive hepatitis C (66.7% vs. 50.4%, p = 0.04), DSM-IV-TR Axis I psychiatric diagnosis (54.0% vs. 41.7%, p = 0.03), and positive urine for opiates (22.6% vs. 8.9%, p = 0.008), cannabis (39.6% vs. 4.0 p < 0.0005) benzodiazepine (BDZ) (77.4% vs. 18.2%, p < 0.0005) and oxycodone (11.3% vs. 0.4%, p < 0.0005). Logistic regression found pregabalin group as more likely to be urine positive to BDZ (OR = 12.8 95%CI 5.0-32.5) cannabis (OR = 22.7, 95%CI 6.3-81.6) and oxycodone (OR = 43.9, 95%CI 3.6-541.4), with higher 21-HAM-D scores (OR = 1.1, 95%CI 1.04-1.2) and hepatitis C sera-positive (OR = 4.1, 95% CI 1.5-11.4). Unexpectedly, 13.2% of the pregabalin group had take-home dose privileges, which are rewards to non-drug abusers. CONCLUSIONS: High prevalence of pregabalin misuse among both BDZ abusers and non-abusers and patients with depressive symptoms supports both the inclusion of routine monitoring for pregabalin and intervention in MMT population.

Stacking-cyclodextrin-microchip electrokinetic chromatographic determination of gabapentinoid drugs in pharmaceutical and biological matrices.

A facile, rapid, and highly sensitive microchip-based electrokinetic chromatographic method was developed for the simultaneous analysis of two gabapentinoid drugs, gabapentin (GPN) and pregabalin (PGN). Both drugs were first reacted with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) via nucleophilic substitution reactions to yield highly fluorescent products with λex/em 470/540nm. Analyses of both fluorescently labeled compounds were achieved within 200s in a poly(methyl methacrylate) (PMMA) microchip with a 30mm separation channel. Optimum separation was achieved using a borate buffer (pH 9.0) solution containing methylcellulose and ß-cyclodextrin (ß-CD) as buffer additives. Methylcellulose acted as a dynamic coating to prevent adsorption of the studied compounds on the inner surfaces of the microchannels, while ß-CD acted as a pseudo-stationary phase to improve the separation efficiency between the labeled drugs with high resolution (Rs>7). The fluorescence intensities of the labeled drugs were measured using a light emitting diode-induced fluorescence detector at 540nm after excitation at 470nm. The sensitivity of the method was enhanced 14- and 17-fold for PGN and GPN, respectively by field-amplified stacking relative to traditional pinched injection so that it could quantify 10ngmL-1 for both analytes, with a detection limit lower than 3ngmL-1. The developed method was efficiently applied to analyze PGN and GPN in their pharmaceutical dosage forms and in biological fluids. The extraction recoveries of the studied drugs from plasma and urine samples were more than 89% with%RSD values lower than 6.2.

Pregabalin Abuse amongst Opioid Substitution Treatment Patients.

Pregabalin (Lyrica®) is used in treating epilepsy, nerve pain and anxiety. Pregabalin was initially thought to have a low misuse potential however there are emerging reports of Pregabalin being abused. A study was commenced at the National Drug Treatment Centre's (NDTC) Drug Analysis Laboratory to determine the level of usage of Pregabalin within the addiction services population in Ireland. A total of 498 urine samples representing samples from 440 individual opioid substitution patients, initially screened by immunoassay for drugs of abuse, were subjected to further analysis for Pregabalin by Liquid Chromatography/Mass Spectrometry (LC/MS). Of 440 patients tested, 39 tested positive for Pregabalin (9.2%). Only 10 patients from this group were prescribed this drug to our knowledge thus giving an estimated rate of misuse of 7.0%. Other drugs detected in the Pregabalin positive patients were Opiates (31.8%), Cocaine (11.4%), Benzodiazepines (79.5%) and Cannabis (77.8%). Our study confirms that Pregabalin abuse is taking place amongst the addiction services population. We believe that misuse of this prescription drug is a serious emerging issue which should be monitored carefully.