Fibromyalgia (FM) is a chronic, multifactorial pain syndrome involving widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive dysfunction, significantly reducing the quality of life of patients. FM is classified under MG30.01, representing chronic widespread pain, within the broader classification of chronic primary pain according to the International Classification of Diseases, 11th Revision. FM has a complex, multifactorial pathophysiology involving peripheral and central mechanisms that contribute to its marked clinical heterogeneity. Currently, FM is diagnosed primarily through clinical assessment using widely accepted criteria, such as the American College of Rheumatology criteria, most recently revised in 2016, which evolved from the widely used 2010/2011 diagnostic framework. A thorough differential diagnosis is required to distinguish FM from a wide range of rheumatic, neurological, endocrine, psychiatric, and other medical disorders. FM management requires a multidisciplinary approach. Non-pharmacological interventions, including patient education, exercise (eg, aerobic and resistance training), and psychological therapies, such as cognitive behavioral therapy, are recommended as first-line treatments. Pharmacological therapies, including pregabalin, duloxetine, milnacipran, and cyclobenzaprine, are Food and Drug Administration-approved and provide clinically meaningful benefits to patients with FM. Although tramadol may be considered, the use of other opioids is generally not recommended because of their limited efficacy and potential risks. Despite the availability of current diagnostic criteria and treatment options, achieving a consistent diagnosis and optimal outcomes in patients remains challenging. Therefore, this narrative review aims to provide a concise, updated, and clinically relevant overview of the current evidence regarding the pathogenesis, diagnosis, and multidisciplinary management of FM to improve diagnostic accuracy and support individualized patient management. Furthermore, future directions should prioritize improving diagnostic precision and developing mechanism-based interventions targeting the underlying pathophysiology of FM.

Sleep bruxism (SB) is a motor activity characterized by repetitive masticatory muscle contractions during sleep, commonly associated with tooth damage and jaw pain or headache. Pharmacological management strategies targeting its central nervous system-related mechanisms remain limited. This study aimed to evaluate whether a low dose of a central muscle relaxant, cyclobenzaprine, reduces SB-related muscle activity, maximum voluntary bite force and self-reported bruxism awareness. A randomized, double-blind, placebo-controlled, crossover clinical trial was conducted. Twenty participants underwent baseline SB motor activity recordings followed by two intervention phases consisting of 5 mg of cyclobenzaprine or placebo for three consecutive nights. Masticatory muscle activity during sleep was quantified using portable surface electromyography. Maximum voluntary bite force was measured using a bite force-recording device. Self-reported outcomes related to SB and secondary effects (e.g., dry mouth) were collected each morning. Comparison of cyclobenzaprine to placebo and baseline nights failed to show a difference in mean frequency of masticatory muscle activity during sleep and maximum voluntary bite force. No self-reported differences were observed for SB awareness. Few secondary effects were identified between cyclobenzaprine use and placebo; a significant increase in perception of tolerable dry mouth upon awakening (p = 0.034) and a marginally statistically significant reduction in the perceived leg movements during sleep (p = 0.046). In conclusion, low-dose cyclobenzaprine was not effective in modifying SB-related muscle activity or masticatory muscle force, suggesting limited clinical utility for SB. Future studies using higher doses of cyclobenzaprine are warranted before ruling out its clinical utility, within a safety profile.

In the second half of 2025, the US Food and Drug Administration approved several new drugs that have relevance for those practicing in primary care. This article highlights the following new medications: brensocatib (Brinsupri), elinzanetant (Lynkuet), and zoliflodacin (Nuzolvence). Additionally, this article reviews newly approved indications for existing therapies, including finerenone (Kerendia) for heart failure with a left ventricular ejection fraction of >_ 40% and cyclobenzaprine hydrochloride sublingual tablets (Tonmya) for fibromyalgia.

Background: Spinal epidural abscesses (SEA) are rare, occurring 2.5-3 times per 10,000 hospital admissions. While streptococcus species comprise 7% of reported SEAs, Group A Streptococcus (GAS) has been described only once in the medical literature to our knowledge. Case presentation: We present a case of GAS pharyngitis with subsequent paraplegia from a GAS SEA. A 33-year-old female presented to the emergency department (ED) and was initially diagnosed with GAS pharyngitis and a suspected strained lower back. Following treatment with amoxicillin, she returned with worsened back pain, radiculopathy, and leukocytosis, for which she was treated with cyclobenzaprine. On her third presentation, she had new bilateral lower extremity weakness with decreased sensation, bilateral ankle clonus, and hyperreflexia. MRI of the thoracic and lumbar spine revealed a multiloculated SEA at T5-T10 requiring laminectomy and abscess evacuation. Intraoperative cultures grew Streptococcus pyogenes. Despite surgery, medical management, and physical therapy, she remained paraplegic. Conclusions: To our knowledge, this is the first report of SEA preceded by GAS pharyngitis. This case exposes the critical association between a recent infection, progression of back pain, eventual neurologic symptoms, and inflammatory markers that should trigger concern for SEA and early evaluation with MRI.

Fibromyalgia (FM) is a chronic nociplastic pain syndrome characterized by widespread pain, nonrestorative sleep, fatigue, and cognitive dysfunction, affecting approximately 2-6% of U.S. adults. Although oral cyclobenzaprine has been used off label for decades, its clinical utility has been limited by a narrow benefit-to-harm ratio, with the number needed to treat for symptomatic improvement approximating the number needed to harm for at least one adverse event at conventional doses. This review examines the mechanistic, pharmacokinetic, and clinical evidence supporting the August 2025 FDA approval of sublingual cyclobenzaprine (TNX-102 SL; Tonmya), the first new pharmacologic treatment approved for FM in more than 15 years.

Temporomandibular disorders (TMDs) comprise a group of multifactorial conditions involving the masticatory muscles, temporomandibular joint, and associated structures influenced by biomechanical, neuromuscular, and biopsychosocial factors. Myogenous TMDs may involve muscle hyperactivity, parafunction, and central sensitization, contributing to chronic pain and functional limitation. Oral skeletal muscle relaxants (SMRs) are commonly used as adjunctive pharmacologic therapy; however, these agents vary considerably in mechanism, efficacy, and safety. This review summarizes the pharmacology, clinical evidence, and risk profiles of commonly prescribed SMRs-including cyclobenzaprine, baclofen, tizanidine, and others-within the context of chronic TMD management. Evidence supports short-term benefit for select agents, though data for chronic daily use remain limited. Given concerns regarding sedation, dependence, hepatotoxicity, and interactions with polypharmacy, clinicians should employ these medications judiciously and primarily for acute exacerbations rather than long-term therapy. An evidence-based, multimodal approach remains essential for optimizing care in patients with chronic TMDs.

Using a combination of computational and experimental methods, the corrosion protection effectiveness provided by cyclobenzaprine (CBA) for carbon steel (CS) in a 1.0 M hydrochloric acid solution was systematically examined. The corrosion protection efficiency and electrochemical behavior of CS with and without different concentrations of CBA were assessed using gravimetric measurements, polarization studies, impedance measurements, and the evaluation of the open circuit potential. The addition of CBA resulted in a notable decrease in double-layer capacitance (Cdl) and an increase in charge transfer resistance (Rct), a considerable increase in the relaxation time constant (τ), as well as a considerable decrease in corrosion rate and corrosion current density, according to gravimetric and electrochemical data. The formation of a surface-bound shielding layer on the CS was demonstrated by surface characterization using SEM/EDS, AFM analysis, wettability assessment via contact angle evaluation, and UV-visible spectroscopic examination. At 192 μmol L[-1], the most effective corrosion protection of ~ 96% was achieved. The results showed that CBA functioned as an effective mixed-type inhibitor. Predominant physical adsorption was indicated by the corrosion inhibition efficiency, which improved with higher inhibitor dosage but decreased as the temperature rose. The thermodynamic and kinetic analyses showed spontaneous adsorption, following the Langmuir isotherm. The electronic characteristics and active adsorption centers of CBA were elucidated through density functional theory calculations, Fukui function examination, and natural bond orbital investigation. Additionally, the significance of π-electron systems and heteroatoms in surface interactions was emphasized.

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.

Meralgia paresthetica is a neuropathic condition generally secondary to extrinsic compression on the lateral femoral cutaneous nerve. Intense local pain is the chief presenting symptom, diagnosis is based on clinical grounds, and the disease is responsive to the removal of the causal agent and antineuralgic medication. We report the case of a 67-year-old male patient who had a ProGrip™ (Medtronic, Minneapolis, MN, USA) (a self-fixating mesh) implanted through laparoscopy after a robotic bilateral inguinal hernia repair. The next day, the patient complained of numbness in the anterolateral aspect of the right thigh along with intolerable stabbing pain. Meralgia paresthetica was diagnosed based on a positive Tinel sign, followed by symptomatic relief after corticosteroids + lidocaine injection. The manifestation was attributed to ProGrip™, and the device was removed. Pain was controlled after discharge with oral pregabalin plus cyclobenzaprine. In a retrospective analysis, no classical risk factors of meralgia paresthetica (e.g., obesity, tight belts, or former local procedures) were identified for the patient under discussion. The authors could not find any similar case in medical literature.

This single-center, open-label, randomized, multiple-dose, pharmacokinetic bridging study was conducted to compare systemic exposure (AUC and Cmax) of a sublingual tablet formulation of cyclobenzaprine hydrochloride (TNX-102 SL, approved as TONMYA) at steady-state with that of an approved reference product, an oral, extended-release (ER) capsule formulation, supporting development under the 505(b)(2) regulatory pathway. Healthy adults (N = 60) were randomly assigned 1:1 to receive two sublingual 2.8-mg tablets or one oral ER 30-mg capsule once daily for 20 days. At steady state, 2 sublingual 2.8 mg tablets provided lower exposure to cyclobenzaprine and norcyclobenzaprine compared with one oral 30-mg ER capsule. However, when exposures were normalized by dose, cyclobenzaprine AUC0-24 and Cmax were higher on both Day 1 and Day 20 with two sublingual tablets versus one oral ER capsule, supporting higher bioavailability of the sublingual tablet formulation. For Day 20, the dose-normalized ratios (two sublingual tablets: one oral ER capsule) for AUC0-τ ss and Cmax ss were 140% and 152%, respectively. Sublingual tablets and oral ER capsules had comparable metabolic profiles of Phase I and II metabolites in plasma over 20 days, with no unique metabolites by the sublingual route. Sublingual cyclobenzaprine HCl tablets were generally safe and well-tolerated.