In addition to other conditions involving increased muscle spasms, centrally acting muscle relaxants (guaifenesin, tolperisone, methocarbamol, chlorzoxazone, diazepam, baclofen and tizanidin) provide relief for a significant proportion of patients suffering from low back pain. Of these, tolperisone has recently been restricted by official decision due to the high incidence of anaphylactic reactions associated with its use. The aim of our work is to analyze the frequency of side effects of this group of drugs in order to help clinicians choose the appropriate medication. According to data from the World Health Organization, tolperisone is considered a safe drug, except for the aforementioned serious allergic side effect. Mortality (including suicide) associated with the administration of these medicines is the highest among the reported side effects for diazepam, followed by tizanidine and methocarbamol. Ineffectiveness was most commonly reported for guaifenesin, followed by baclofen and tizanidine. Tolperisone was the most favorable drug in terms of both mortality and ineffectiveness. We present in detail the gastrointestinal, major neurological, and psychiatric side effects that make it difficult, and in some cases impossible, to take the drugs, and we also mention the disturbing skin and eye symptoms. Orv Hetil. 2026; 167(31): 1224-1230.

This work introduces an eco-friendly spectrophotometric approach for the simultaneous quantification of methocarbamol (MET) and its impurity product guaifenesin (GUF), based on measuring the second derivative amplitudes of each drug in presence of the other, using zero-crossing technique. The second derivative amplitudes were measured at 208.0 nm and at 207.5 nm for MET and GUF, respectively. The proposed method showed good linearity over the concentration ranges of 1.0-110.0 and 1.0-90.0 µg/mL for MET and GUF, respectively with corresponding correlation coefficient of 0.9997 and 0.9999. The detection and quantitation limits for MET were found to be 0.021 and 0.064 µg/mL, respectively, while GUF corresponding values were 0.013 and 0.041 µg/mL. The method was successfully applied for determining MET and GUF in its dosage forms with high selectivity. The developed method produced comparable results to those obtained by the published reference methods in terms of precision and accuracy. A comprehensive assessment was carried out to evaluate the suggested method's economic feasibility, practicality, and environmental sustainability compared to previously reported techniques. This comprehensive assessment leveraged several state-of-the-art tools, including the analytical Eco-scale, Green Analytical Procedure Index (GAPI), Analytical GREEnness (AGREE), Multi-Color Assessment, Analytical Green Star Area (AGSA) and Blueness Assessment Graphical Index tools. The suggested approach exhibited favorable quadrant profiles in GAPI assessment, along with higher AGREE, AGSA and Eco-scale scores, all of which confirmed their eco-friendliness.

This study evaluated the chemical and microbiological stability of six oral liquid formulations, benazepril hydrochloride, candesartan cilexetil, disulfiram, fluconazole, methocarbamol, and pentoxifylline, compounded in the suspending vehicle SyrSpend® SF PH4. Stability-indicating UHPLC methods were validated for each API and confirmed to be specific, precise, accurate, and linear within the analytical ranges tested. Forced degradation studies ensured method suitability for detecting potential decomposition pathways. Chemical stability was assessed over 90 days under room temperature and refrigerated storage, alongside pH monitoring and visual inspection. Antimicrobial effectiveness testing (USP <51>, Category 3: oral aqueous products) demonstrated that all formulations met preservative efficacy criteria at the final assigned BUD. Results revealed API-specific stability profiles: several formulations remained within 90-110% of label claim for up to 90 days, while others showed temperature degradation patterns dictating shorter BUDs. Overall, SyrSpend® SF PH4 proved to be a versatile and reliable vehicle for compounded oral liquids, supporting extended BUDs while maintaining physicochemical integrity and microbiological quality. These findings reveal dependent degradation patterns that dictate shorter BUDs. Overall, SyrSpend® SF PH4 proved to be a versatile and reliable vehicle for compounded oral liquids, supporting extended BUDs while preserving physicochemical integrity and microbiological quality. These findings provide evidence-based guidance for compounding pharmacists and reinforce the role of SyrSpend® SF PH4 in personalized pharmacotherapy.

Molecular mimicry is hypothesized to play a key role in the pathogenesis of acute polyradiculoneuritis (APRN) in dogs, as in Guillain-Barré syndrome (GBS). GBS is linked to Campylobacter jejuni and cytomegalovirus, while Parvovirus B19 shows temporal and serological associations. In dogs, the cause of APRN is often unknown, although recent vaccination or ingestion of raw poultry contaminated with Clostridium perfringens is documented. Antiganglioside antibodies are potential serum biomarkers for APRN. Eight 2.5-month-old Sprocker littermates and a 3-month-old female Cockapoo developed severe gastrointestinal clinical signs and tested positive for canine parvovirus-2 (CPV-2) infection. Six littermates died, while two pups (one male, one female) and the Cockapoo recovered. Seven days later, the male puppy developed pelvic limb weakness progressing to flaccid tetraparesis over 24 h, followed by thoracic limb contracture. Both female pups, 10 days after recovering from illness, developed neuromuscular clinical signs that deteriorated for 9 days before improving. They presented with a short-strided, choppy gait with kyphosis, and the Cockapoo developed dysphonia. Both female puppies improved over several months. Antiganglioside antibodies were not detected in the two littermates at 1 and 3 months after clinical onset. Treatment included supportive care. Both littermates received prednisolone and methocarbamol, with only the female responding. The male was euthanized due to poor quality of life. Post-mortem examination revealed widespread muscular atrophy and axonal degeneration, with active regeneration detected on semi-thin tissue sections of nerves. This study described a peripheral neuropathy temporally associated with CPV-2 infection. Although a causal relationship cannot be established, the clinical course and pathological features are compatible with a post-infectious neuromuscular process.

This study introduces a twin enrichment strategy based on dual-template molecularly imprinted polymer-assisted solid-phase microextraction coupled with dispersive liquid-liquid microextraction (MISPE-DLLME) for the simultaneous extraction and determination of favipiravir and remdesivir in biological matrices (blood and urine), followed by high-performance liquid chromatography with ultraviolet detection (HPLC-UV) analysis. The dual-template molecularly imprinted polymer (DT-MIP) was synthesized via precipitation polymerization and comprehensively characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) surface area analysis, simultaneous thermal analysis (STA), and X-ray diffraction (XRD). Under optimized conditions, including pH 2.00 ± 0.1, 10.0 mg of MIP, 200 ± 5 μL of 1-dodecanol, 500 ± 10 μL of methanol, and an extraction time of 10.0 ± 0.5 min, the method afforded high recoveries of 103-110% with relative standard deviations (RSDs) below 5% (n = 3). The method showed excellent sensitivity, with limits of detection of 1.0 ng/mL for favipiravir and 0.40 ng/mL for remdesivir and limits of quantification of 3.3 ng/mL and 1.3 ng/mL, respectively. Selectivity was evaluated against ten structurally related drugs (ibuprofen, gemfibrozil, paracetamol, diazepam, clobazam, methocarbamol, theophylline, naproxen, dimenhydrinate, and cinnarizine) at various concentration ratios, and the DT-MIP displayed superior recognition performance compared with the corresponding non-imprinted polymer (NIP). Analysis of clinical samples yielded acceptable recoveries and precision, confirming the reliability of the proposed method and its potential applicability in therapeutic drug monitoring of COVID-19 antivirals.

An 86-year-old woman presented to the emergency department following a ground-level fall with fractures of the left posterior ribs 9-11 and right posterior ribs 5-8. She was admitted, and multimodal pain management, including acetaminophen, methocarbamol, oxycodone, and hydromorphone, was initiated. On the second day of hospitalization, she developed somnolence and confusion attributed to opioid administration. She was unable to receive a thoracic epidural due to recent clopidogrel administration, and bilateral erector spinae plane catheters were shown to be a reasonable alternative. This intervention provided effective pain relief, leading to improved mental status, pain control, and incentive spirometry.

Background: Pain is prevalent among critically ill patients and is frequently underrecognized due to sedation and mechanical ventilation. Opioids remain the primary analgesic therapy in the intensive care unit (ICU); however, opioid-related adverse effects have prompted increased adoption of multimodal analgesia strategies. Centrally acting skeletal muscle relaxants, including cyclobenzaprine and methocarbamol, are commonly used as adjuncts, yet data evaluating their anticholinergic adverse effects in critically ill populations are limited. Methods: The primary objective of this study is to determine the prevalence of anticholinergic adverse drug events (ADEs) associated with cyclobenzaprine and methocarbamol among ICU patients. Purpose: This retrospective cohort study evaluated adult patients (≥18 years) admitted to any ICU at a single academic medical center between January 1, 2023 and January 31, 2025, who received at least 1 dose of cyclobenzaprine or methocarbamol during ICU admission. The primary outcome was the prevalence of anticholinergic ADEs, identified through provider documentation and International Classification of Diseases, Tenth Revision (ICD-10) codes. Secondary outcomes included types of ADEs, dosing of the study drugs, and medication discontinuation rates. Results: Of 367 eligible patients, 260 were included in the final analysis. Cyclobenzaprine was administered to 112 patients (43%) and methocarbamol to 148 patients (57%). Potential anticholinergic ADEs were identified in 29 patients (14.4%) receiving cyclobenzaprine and 17 patients (10.8%) receiving methocarbamol. Among the 69 total ADEs, 55 (79%) prompted an intervention, most commonly pharmacologic therapy adjustments. Medication discontinuation due to ADEs was infrequent. Conclusions: Cyclobenzaprine and methocarbamol were associated with anticholinergic adverse effects in critically ill ICU patients, though this did not translate to medication discontinuation. These findings support the cautious use of centrally acting muscle relaxants as part of multimodal analgesia strategies. Pharmacists are uniquely positioned to evaluate and mitigate adverse drug effects in the critically ill.

A common combination of methocarbamol (MTH) and diclofenac potassium (DCL K) relieves musculoskeletal pain and inflammation through centrally acting muscle relaxants. A dual-function RP-HPLC method was used to analyze the assay and dissolution testing of MTH and DCL K simultaneously. As part of the suggested method, green and white analytical chemistry standards were incorporated to ensure sustainability and compatibility. We performed a chromatographic separation on a C8 column (15 cm × 4.6 mm, 5 μm) with a mobile phase of phosphate buffer and ethanol (30:70 v/v), adjusted to pH 2.5 ± 0.1, yielding sharp and well-resolved peaks with retention times of 2.183 min for MTH and 6.652 min for DCL. A 275-nm dual UV detector was used to detect the separation at a flow rate of 1.0 mL/min. Sensitivity parameters demonstrated low detection capabilities, with limits of detection (LOD) of 0.069 μg/mL for MTH and 0.012 μg/mL for DCL, and limits of quantification (LOQ) of 0.210 μg/mL and 0.035 μg/mL. Over an extended sample period of 30 min with 100 revolutions per minute (rpm), USP Apparatus II (Paddle) was used to measure dissolution at a temperature of 37.0 ± 0.5°C in phosphate buffer (pH 6.8). With both active pharmaceutical ingredients, 75% of the drug was released within 30 min. A combination of suitability (RSD 2%) and precision (raw data 2%) makes the method an excellent choice for routine quality control. In keeping with the changing environment and regulatory requirements, pharmaceutical analysis can become more efficient and sustainable. Accelerated stability studies were conducted on the finished dosage form under ICH-recommended conditions for 6 months. Sustainability was assessed using the Analytical Eco-Scale, Environmental and Practical Performance Index (EPPI), and Click Analytical Chemistry Index (CACI). The method achieved an Eco-Scale score of 91, classifying it as an excellent green method, an EPPI score of 97.9, and a CACI score of 80, confirming its efficiency and practicality for routine quality control.

A reusable transition-metal-free catalytic system has been developed to facilitate the dehydrative sulfonamidation of primary and secondary allylic alcohols under mild reaction conditions. The method employs p-toluenesulfonic acid as an immobilized Brønsted acid on a silica gel solid-support, and the catalytic system has been shown to be recyclable without significant loss of activity for 3-5 uses. A wide range of sulfonamide and allylic alcohol substrates are tolerated in this transformation, and products have been isolated from reactions employing known pharmaceuticals such as celecoxib and methocarbamol as nucleophilic substrates. The antibacterial, antifungal, and cytotoxic properties of the isolated products was investigated along with their activity as metabolic inhibitors of ATP production.

Rheumatoid arthritis (RA) is a chronic autoimmune disease. Early diagnosis and intervention are critical, and contaminated medications can complicate or obscure the diagnosis of autoimmune diseases. Herein, we report a case of a 38-year-old man who presented with two to three months of worsening arthralgias and myalgias. He reported using AK Forte, a natural supplement from Mexico that was recalled by the FDA for contamination with diclofenac, dexamethasone, and methocarbamol. AK Forte is a popular supplement used in Latin America, especially amongst manual laborers and other physically demanding job workers, and is easily accessible over the counter. The patient also reported Cushingoid symptoms such as weight gain, facial puffiness, and stretch marks. Upon abruptly discontinuing AK Forte, the patient presented to the emergency department with worsening arthralgias, myalgias, intermittent fever, and tachycardia. Despite being on a supplement contaminated with steroids, the patient did not present with symptoms of adrenal insufficiency throughout his hospital course. After ruling out infectious causes, the patient was diagnosed with persistent sinus tachycardia associated with high RA inflammatory activity. This case demonstrates the importance of obtaining a thorough medication history, including over-the-counter drugs, vitamins, and herbal supplements. This case also highlights the risks associated with unregulated supplements, especially those sold outside the United States, as they may not adhere to FDA standards and may be contaminated with pharmacologically active ingredients, affecting their safety, efficacy, and quality.

For treatment of muscle spasms associated pain, combination of nonsteroidal anti-inflammatory drugs like diclofenac (DIC) and muscle relaxants as methocarbamol (MET) is usually utilized. This work represents a novel, rapid, facile, sensitive, and selective first derivative synchronous fluorescence spectroscopy (FDSFS) for the simultaneous determination of DIC and MET in their combined tablets. Factors influencing method's sensitivity were investigated, and the best findings were accomplished applying Δ λ = 60 nm and using water as a diluting solvent. Through applying the optimized experimental conditions, DIC showed a lower detection limit of 0.15 µg/mL and a quantitation limit of 0.30 µg/mL, while MET corresponding values were 0.03 µg/mL and 0.05 µg/mL. Diclofenac was measured at 288 nm, while methocarbamol was measured at 346 nm, exhibiting linearity over the concentration ranges of 0.3-2.5 and 0.05-5.0 µg/mL, respectively. Through application to several laboratory-prepared mixtures and commercial formulation, the suggested method's applicability was determined. When comparing the proposed method to the reported HPLC method using the student's t-test and F-ratio test, no discernible differences were found. Due to simplicity and economical advantage of the method, it can be applied in quality control laboratories for analysis of the studied drugs. The evaluation of the method's eco-friendliness and greenness was also performed using Analytical GREEnness (AGREE), Green Analytical Procedure Index (GAPI) and Analytical Green Star Area (AGSA) metrics. Complete validation procedures were applied to the suggested approach in compliance with the International Conference on Harmonization's criteria.

Methocarbamol (MT), a centrally acting muscle relaxant, presents significant analytical challenges due to its low ultraviolet (UV) absorptivity, rapid metabolism, and pronounced pH-dependent instability. The presence of guaifenesin-related impurities and interference from co-formulated analgesics further complicate its detection in pharmaceutical, biological, and environmental matrices. This review compiles peer-reviewed English-language studies indexed in Scopus, Web of Science, PubMed, ScienceDirect, and Google Scholar and provides a critical assessment of MT quantification methods developed over the past 25 years. Evidence shows that optimized high-performance liquid chromatography (HPLC), particularly fluorescence-based systems, provides the highest sensitivity and selectivity, achieving sub-ng/mL detection and overcoming limitations of UV assays, such as signal suppression and narrow linear ranges. Electrochemical approaches using CNT-, graphene-, MOF-, and magnetic-nanocomposite-modified electrodes enhance redox discrimination and enable nM-μM detection. Chemometric-assisted spectroscopic techniques offer rapid, low-cost analysis suitable for simple formulations but lack reliability in complex matrices. Across all platforms, strict pH control, rapid processing, and selective extraction methods-such as solid-phase extraction (SPE), molecularly imprinted polymer (MIP), and dispersive liquid-liquid microextraction (DLLME) remain essential to reduce degradation and matrix interference. Future progress will rely on miniaturized microfluidic systems, improved stability-indicating chromatography, and intelligent electrochemical sensors capable of multiplex quantification in challenging samples.