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The use of physiologically based biopharmaceutics modeling (PBBM) and bioequivalence safe space is increasingly common for immediate-release drug products. However, for extended-release (ER) formulations there are only a few examples of this application. In this study, we developed ER formulations containing cyclobenzaprine 15 mg, supported by PBBM and bioequivalence safe space. Four formulations were prepared, F1, F2, F3 (ER mini-tablet formulations) and F4 (ER tablet formulation), and the dissolution profiles were evaluated. The dissolution profile of the reference drug product was also evaluated and used to set a bioequivalence safe space. A PBBM was set up, evaluated, and used to predict the in vivo behavior of the formulations. The bioequivalence safe space was calculated to be between – 25% and + 75% of the k1 and Tlag values of the dissolution profile of the reference drug product when applying the first-order dissolution kinetic model. All time points of the dissolution profile of the ER mini-tablet formulation F2, were within the safe space, and was approved in 10 of 10 trials of crossover virtual bioequivalence studies. Based on the PBBM strategy and bioequivalence safe space, it was possible to develop an ER mini-tablet formulation virtually bioequivalent to the reference drug product, even though this formulation failed the f2 test. [Display omitted] • Formulation development based on PBBM and bioequivalence safe space. • Failing similarity factor f2 but approved on virtual bioequivalence study. • Higher surface area from ER mini-tablets driving drug dissolution. [ABSTRACT FROM AUTHOR]

With musculoskeletal back pain being one of the most common presentations in the emergency department, evidence-based management strategies are needed to address such complaints. Along with other medications, cyclobenzaprine is a muscle relaxant commonly prescribed for patients complaining of musculoskeletal pain, in particular, pain associated with muscle spasms. However, with recent literature questioning its efficacy, the role of cyclobenzaprine use in patients with musculoskeletal back pain remains unclear. The objective of the study is to investigate trends of cyclobenzaprine utilization among patients presenting to the emergency department (ED) in the United States. This is a retrospective cohort review of data obtained from the National Hospital Ambulatory Medical Care Survey (NHAMCS) between 2007 and 2019. We analyzed ED visits of patients 18 years and older. Visits during which cyclobenzaprine was administered in the ED or prescribed at discharge were identified. Trends were described using a time series analysis of patients' visits who received administration and prescriptions of cyclobenzaprine. Between 2007 and 2019, we identified an estimated 1.35 billion ED visits, 57.2% (772.6 million) were female. From that sample, 2.4% (32.7 million) of all visits received cyclobenzaprine prescription in the ED only, and 0.5% (6.6 million) of total visits were both given the drug in the ED and were prescribed the drug at discharge). Overall trend analysis shows a slight decrease in annual percentages of cyclobenzaprine administration and prescriptions during the study period. Visits of certain subgroups: 26–44 years, white showed relatively higher percentages of administration and prescription of cyclobenzaprine. Although there was a slight decrease, our study still shows significant cyclobenzaprine utilization in the ED, despite conflicting evidence demonstrating efficacy for patients with musculoskeletal complaints and the concern for adverse effects. Additional studies are needed to examine its overall effectiveness and risk-benefit analysis in treating patients with such conditions. [ABSTRACT FROM AUTHOR]

Background: Low back pain (LBP) causes 2.6 million visits to U.S. emergency departments (EDs) annually. These patients are often treated with skeletal muscle relaxants (SMRs).Objectives: The goal of this study was to determine whether efficacy of SMRs is associated with age, sex, or baseline LBP severity.Methods: This was a planned analysis of data from 4 randomized studies of patients with acute nonradicular LBP. Patients were enrolled during an ED visit and followed-up 1 week later. The primary outcome was improvement in the Roland-Morris Disability Questionnaire (RMDQ) between ED discharge and the 1-week follow-up. We compared the change in RMDQ among 8 groups: placebo, baclofen, metaxalone, tizanidine, diazepam, orphenadrine, methocarbamol, and cyclobenzaprine. All patients also received a nonsteroidal anti-inflammatory drug. We performed analysis of variance to determine statistically significant differences between medications and linear regression to determine the association of age, sex, and baseline severity with the primary outcome.Results: The mean improvement in RMDQ per group was placebo 10.5 (95% confidence interval [CI] 9.5-11.5), baclofen 10.6 (95% CI 8.6-12.7), metaxalone 10.3 (95% CI 8.1-12.4), tizanidine 11.5 (95% CI 9.5-13.4), diazepam 11.1 (95% CI 9-13.2), orphenadrine 9.5 (95% CI 7.4-11.5), methocarbamol 8.1 (95% CI 6.1-10.1), and cyclobenzaprine 10.1 (95% CI 8.3-12). The between-group differences were not statistically significantly different. Results were similar regardless of age, sex, and baseline severity. Higher baseline RMDQ was associated with greater clinical improvement (B coefficient 5.7, p < 0.01). Adverse medication effects were more common with cyclobenzaprine than with placebo (p < 0.01).Conclusions: Among patients in the ED with acute LBP treated with a nonsteroidal anti-inflammatory drug, SMRs do not improve outcomes more than placebo. Neither age, sex, nor baseline impairment impacts these results. [ABSTRACT FROM AUTHOR]

• Intestinal Ischemia /Reperfusion(I/R) injury causes inflammatory response. • Inflammatory response from (I/R) injury activates toll-like receptor4(TLR4). • Activated TLR4 is leading to activation of TRIF-MYD88 pathway. • TRIF-MYD88 pathway is responsible for induction inflammatory-immune response. • TLR4 inhibitors are involved in decreasing activated TRIF-MYD88 pathway. Intestinal ischemia/reperfusion (I/R) injury is a serious condition that causes intestinal dysfunction and can be fatal. Previous research has shown that toll-like receptor 4 (TLR4) inhibitors have a protective effect against this injury. This study aimed to investigate the protective effects of TLR4 inhibitors, specifically cyclobenzaprine, ketotifen, amitriptyline, and naltrexone, in rats with intestinal (I/R) injury. Albino rats were divided into seven groups: vehicle control, sham-operated, I/R injury, I/R-cyclobenzaprine (10 mg/kg body weight), I/R-ketotifen (1 mg/kg body weight), I/R-amitriptyline (10 mg/kg body weight), and I/R-naltrexone (4 mg/kg body weight) groups. Anesthetized rats (urethane 1.8 g/kg) underwent 30 min of intestinal ischemia by occluding the superior mesenteric artery (SMA), followed by 2 h of reperfusion. Intestinal tissue samples were collected to measure various parameters, including malondialdehyde (MDA), nitric oxide synthase (NO), myeloperoxidase (MPO), superoxide dismutase (SOD), TLR4, intercellular adhesion molecule-1 (ICAM-1), nuclear factor kappa bp65 (NF-ĸBP65), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), macrophages CD68, myeloid differentiation factor 88 (MYD88), and toll interleukin receptor-domain-containing adaptor-inducing interferon β (TRIF). The use of TLR4 inhibitors significantly reduced MDA, MPO, and NO levels, while increasing SOD activity. Furthermore, it significantly decreased TLR4, ICAM-1, TNF-α, MCP-1, MYD88, and TRIF levels. These drugs also showed partial restoration of normal cellular structure with reduced inflammation. Additionally, there was a decrease in NF-ĸBP65 and macrophages CD68 staining compared to rats in the I/R groups. This study focuses on how TLR4 inhibitors enhance intestinal function and protect against intestinal (I/R) injury by influencing macrophages CD86 through (MYD88-TRIF) pathway, as well as their effects on oxidation and inflammation. [ABSTRACT FROM AUTHOR]

A previously healthy 13-year-old adolescent girl presented with loss of consciousness, slurred speech, abnormal upper extremity movements, and progressive difficulty walking. She developed headache the morning of presentation that was then followed by slurred speech, flexion of her upper extremities, and then loss of consciousness. Her examination was remarkable for sinus tachycardia, unresponsiveness, and repeated upper extremity movements. She was intubated for airway protection and extubated on hospital day 2 when her mental status improved. She reported blurry vision and urinary retention initially which improved throughout hospitalization. Her mental status returned to baseline by hospital day 5, and her heart rate normalized on hospital day 10. Comprehensive drug screen returned positive for cyclobenzaprine (Flexeril, Amrix). Cyclobenzaprine overdose is characterized by anticholinergic symptoms. Despite chemical similarity to tricyclic antidepressants, ventricular dysrhythmias are uncommon. [ABSTRACT FROM AUTHOR]

Abstract: Background: The single-dose pharmacokinetic profile of cyclobenzaprine extended-release (CER) has been previously characterized and compared with the pharmacokinetics of cyclobenzaprine immediate-release (CIR) administered 3 times daily for 3 doses. Objective: The objective of this study was to characterize the multiple-dose pharmacokinetic properties of once-daily CER 30 mg and CIR 10 mg TID formulations in healthy volunteers. Methods: In this double-blind, single-center, 2-period crossover study, healthy subjects were randomized to dosing sequences with once-daily CER 30 mg or CIR 10 mg TID for 7 days. Subjects crossed over to the alternative regimen following a 14-day washout period. Pharmacokinetic assessments at steady state included area under the plasma cyclobenzaprine concentration–time curve over the dosing interval (AUC0–τ,ss), peak plasma cyclobenzaprine concentration (Cmax,ss), time to observed Cmax (Tmax,ss), observed minimum cyclobenzaprine concentration (Cmin,ss), average cyclobenzaprine concentration (Cavg,ss), accumulation ratio (Rac), and terminal elimination half-life (t½). Tolerability and safety assessments were conducted. Results: A total of 36 subjects were randomized; 34 completed both dosing periods (1 subject was lost to follow-up, 1 withdrew consent). Steady state was reached for CER 30 mg on day 7. Mean Cmax,ss, Cmin,ss, and Cavg,ss were 41.1, 21.4, and 31.4 ng/mL, respectively. The median Tmax,ss for CER 30 mg was 7.0 hours, with a mean t½ of 34.8 hours. At steady state, CER produced a sustained plasma cyclobenzaprine concentration with a single peak in plasma concentration during the 24-hour dose interval. The Rac for CER was 2.65. Because of a protocol violation (insufficient data), no steady-state pharmacokinetic assessments could be performed for CIR. Most adverse events were mild or moderate in intensity. Somnolence was the most frequently reported adverse event (100% of subjects) in those receiving CER, followed by dry mouth (58%), dizziness (19%), and headache (17%). Conclusions: Once-daily CER 30 mg delivered sustained plasma cyclobenzaprine levels over 24 hours at steady state. Owing to a protocol violation, steady-state pharmacokinetic properties for CIR could not be assessed. [Copyright &y& Elsevier]

Abstract: Objective: The purpose of this study was to compare the pharmacokinetics and tolerability of single oral doses of cyclobenzaprine extended-release (CER) 15- and 30-mg capsules. Methods: This was a randomized, double-blind, 2-period crossover study in healthy adults aged 18 to 40 years. Subjects were assigned to receive a single dose of either CER 15 mg or 30 mg on days 1 and 15, separated by a 14-day washout. Study comparisons included the plasma cyclobenzaprine AUC to 168 hours after dosing (AUC0–168), AUC0–∞, and Cmax. Plasma cyclobenzaprine Tmax, terminal elimination t1/2, and adverse events (AEs) were also assessed. Results: Sixteen subjects (9 women, 7 men) were randomized to receive cyclobenzaprine 15 mg or 30 mg; 13 (81.3%) were white and 3 (18.8%) were black. Mean age and weight were 30.2 years and 70.7 kg, respectively. The shapes of the pharmacokinetic profiles for CER 15 and 30 mg were parallel. Mean observed values for dose-dependent pharmacokinetic parameters of CER 15 and 30 mg were as follows: AUC0–168, 318.3 and 736.6 ng · h/mL, respectively; AUC0–∞), 354.1 and 779.9 ng · h/mL; and Cmax, 8.3 and 19.9 ng/mL. Dose-independent parameters were comparable across doses. Median observed Tmax was 6.0 hours for both CER doses; mean t1/2 was 33.4 hours for CER 15 mg and 32.0 hours for CER 30 mg. The bioavailability of the 2 doses, as indicated by the least squares mean AUC0–∞, was 330.3 ng · h/mL for CER 15 mg and 755.1 ng · h/mL for CER 30 mg. During the CER 15-mg treatment sequence, 5 subjects experienced 5 AEs (headache, dizziness, musculoskeletal pain, dermatitis, and glossodynia); during the CER 30-mg treatment sequence, 2 subjects experienced 2 AEs (somnolence and dysmenorrhea). All AEs were mild in intensity. No serious AEs occurred during the study. Conclusions: Once-daily CER 15 and 30 mg exhibited similarly shaped pharmacokinetic profiles. AUC0–168, AUC0–∞), and Cmax values for the 30-mg dose were approximately double those for the 15-mg dose, a result consistent with previously reported data on the dose proportionality of cyclobenzaprine immediate release. [Copyright &y& Elsevier]

Objective: To determine the weight variation and calculated dosing variability of tablet fragments upon splitting unscored cyclobenzaprine hydrochloride 10 mg tablets using two common tablet splitting devices.Design: Comparative pharmaceutics study.Setting: Pharmacy school laboratory.Participants: Not applicable.Interventions: Unscored cyclobenzaprine hydrochloride 10 mg tablets from one generic manufacturer were split with a tablet splitter or a kitchen knife by a licensed pharmacist and two doctor of pharmacy students (n = 15 tablets for each method per participant).Main Outcome Measures: Fragment weights (FWs) were compared with the theoretical weights (TWs), which were calculated as one half of the mean weight of the tablets used in each part of the experiment; means, relative standard deviations (RSDs), and percentages of TW were also calculated.Results: The mean weight before splitting the 45 tablets with the tablet splitter was 136.6 +/- 2.1 mg (TW = 68.3 mg). The mean FW after splitting was 67.9 +/- 7.9 mg. The RSD of 11.6% corresponded to a range of 69.4% to 130.2% of the TW and an estimated drug content of the split fragments between 3.47 mg and 6.51 mg. The mean weight before splitting the 45 tablets cut with a kitchen knife was 136.6 +/- 2.0 mg (TW = 68.3 mg). The mean FW was 68.0 +/- 15.7 mg with a RSD of 23.2%, corresponding to a range of 49.9% to 149.5% of the TW and an estimated drug content of the split fragments between 2.49 mg and 7.48Conclusion: Tablet fragments obtained after splitting this generic cyclobenzaprine 10 mg product varied considerably in weight and estimated drug content. Accordingly, splitting cyclobenzaprine 10 mg tablets to achieve 5 mg doses could result in unpredictable dosing and therapeutic response. [ABSTRACT FROM AUTHOR]

Background: Cyclobenzaprine hydrochloride is a muscle relaxant that is effective in improving muscle spasm, reducing local pain and tenderness, and increasing range of motion in acute, painful musculoskeletal conditions. Sedation is the most common adverse event associated with its use at the usual dosage of 10 mg TID. Studies in healthy adults sugges that a lower dose may produce less sedation. Because cyclobenzaprine''s duration of action is 4 to 6 hours, reducing the dosing frequency to 10 mg BID would create a potentially painful untreated interval between doses. The alternative is administration of a lower dose (eg, 5 or 2.5 mg) TID.Objective: These studies were designed to assess the efficacy and tolerability of cyclobenzaprine 2.5, 5, and 10 mg TID compared with placebo in patients with acute musculoskeletal spasm.Methods: In 2 randomized, double-blind, placebo-controlled, parallel-group trials conducted at primary care centers in the United States, adult patients with acute painful muscle spasm of the lumbar or cervical region were randomly assigned to receive treatment with 2.5, 5, or 10 mg cyclobenzaprine TID or placebo for 7 days (study 1: cyclobenzaprine 5 or 10 mg TID or placebo; study 2: cyclobenzaprine 2.5 or 5 mg TID or placebo). The primary efficacy measures were patient-rated clinical global impression of change, medication helpfulness, and relief from starting backache. Neither study included a nonsteroidal anti-inflammatory drug (NSAID) as an active control. Although physicians frequently prescribe an analgesic or NSAID in addition to cyclobenzaprine, these studies were not designed to assess whether adding cyclobenzaprine provides a benefit over that of an analgesic.Results: One thousand four hundred five patients (737 study 1; 668 study 2), two thirds with low back pain and one third with neck pain, were randomized to treatment. Their mean age was 42 years, and ∼89% were white. In both studies, patients receiving cyclobenzaprine 5 or 10 mg had significantly higher mean scores on the primary efficacy measures compared with those receiving placebo (study 1—P≤0.001 cyclobenzaprine 5 and 10 mg vs placebo, all measures at visits 2 and 3; study 2—P≤0.03 cyclobenzaprine 2.5 mg vs placebo, relief from starting backache on day 3 only; cyclobenzaprine 5 mg vs placebo, patient-rated clinical global impression of change, medication helpfulness, and relief from starting backache at visit 3 or day 7 only). On day 7, significantly more patients receiving cyclobenzaprine 5 or 10 mg reported relief compared with placebo recipients (P < 0.05 all cyclobenzaprine groups vs placebo). Onset of relief was apparent within 3 or 4 doses of the 5-mg regimen. In the subanalysis of the proportion of responders in the pooled 5-mg groups who did and did not report somnolence, a meaningful treatment effect was observed on all primary efficacy variables in patients who did not report somnolence, suggesting that efficacy was indendependent of sedation. Cyclobenzaprine was well tolerated. Somnolence and dry mouth, the most common adverse effects, were mild and dose related. Overall, ≥ 1 adverse event was reported in 54.1%, 61.8%, and 35.4% of patients receiving cyclobenzaprine 5 or 10 mg or placebo, respectively, in study 1 and by 43.9%, 55.9%, and 35.4% of patients receiving cyclobenzaprine 2.5 or 5 mg or placebo, respectively, in study 2. Adverse events were the primary reason for discontinuation of treatment in the cyclobenzaprine 5- and 10-mg groups in both studies. In study 2, ineffectiveness of therapy was the main reason for discontinuation of therapy in the group receiving cyclobenzaprine 2.5 mg.Conclusions: Cyclobenzaprine 2.5 mg TID was not significantly more effective than placebo. The cyclobenzaprine 5- and 10-mg TID regimens were associated with significantly higher mean efficacy scores compared with placebo. Cyclobenzaprine 5 mg TID was as effective as 10 mg TID, and was associated with a lower incidence of sedation. [Copyright &y& Elsevier]

The centrally acting muscle relaxant cyclobenzaprine decreases the amplitude of monosynaptic reflex potentials by inhibiting the facilitatory descending serotonergic influences in the spinal cord. Interestingly, the structure of cyclobenzaprine is much similar to those of amitriptyline and cyproheptadine. In the present study, we attempted to elucidate the relationship between 5-HT2 receptor antagonistic and inhibitory effects of cyclobenzaprine, amitriptyline, cyproheptadine and ketanserin on the spinal reflexes. Cyclobenzaprine, amitriptyline, cyproheptadine, and ketanserin significantly inhibited facilitatory effects of 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) on flexor reflexes and mono- and polysynaptic spinal reflex potentials in spinalized rats. In intact rats, these drugs significantly reduced the mono- and polysynaptic reflex potentials. 5-HT depletion significantly prevented the depression of the spinal reflex potentials induced by these drugs. These results suggest that the inhibitory effects of cyclobenzaprine, amitriptyline, and cyproheptadine on mono- and polysynaptic reflex potentials are due to the inhibition of descending serotonergic systems through 5-HT2 receptors in the spinal cord. [Copyright &y& Elsevier]

6-nitrodopamine (6-ND) is released from human umbilical cord vessels and modulates vascular reactivity by acting as a dopamine antagonist. Here we investigate whether 6-ND is released by the rat isolated vas deferens and its effect on this tissue. Dopamine, noradrenaline, adrenaline and 6-ND levels were quantified in rat isolated vas deferens by LC-MS-MS. Electric-field stimulation (EFS) and concentration-response curves to 6-ND, noradrenaline, dopamine and adrenaline were performed in the absence and in the presence (30 min) of L-NAME, SCH-23390, haloperidol, PG-01037, sonepiprazole, desipramine, clomipramine, amitriptyline, cyclobenzaprine, carbamazepine, maprotiline, paroxetine, oxcarbazepine and ketanserin in the rat isolated epididymal vas deferens (RIEVD). Basal releases of 6-ND and noradrenaline were detected from the rat isolated vas deferens. 6-ND release was reduced by tissue incubation with L-NAME and from the vas deferens obtained from L-NAME-treated rats. SCH-23390 caused leftward shifts on concentration-response curves to 6-ND without affecting dopamine- or EFS-induced RIEVD contractions. Haloperidol, PG-01037 and sonepiprazole caused significant rightward shifts on concentration-response curves to dopamine but had no effect on either the 6-ND or EFS-induced RIEVD contractions. The tricyclic compounds desipramine, clomipramine, amitriptyline, cyclobenzaprine and carbamazepine induced rightward shifts on 6-ND concentration-response curve but did not reduce the noradrenaline, dopamine and adrenaline contractile responses. They also reduced the EFS-induced RIEVD contractions in control but not in tissues obtained from L-NAME-treated animals. Maprotiline, oxcarbazepine, paroxetine and ketanserin had no effect in either 6-ND or EFS-induced RIEVD contractions. Thus, 6-ND modulates RIEVD contractility, and desipramine, clomipramine, amitriptyline, cyclobenzaprine and carbamazepine act as selective 6-ND receptor antagonists. [ABSTRACT FROM AUTHOR]

I• Military-related PTSD responds poorly to current pharmacotherapies • Sublingual cyclobenzaprine 5.6 mg for 12 weeks nominally reduced PTSD severity over placebo • Improvement in sleep and psychosocial function also observed • Early sleep improvement predicted degree of improvement in PTSD severity • Treatment was well tolerated with numerically higher completion rates in drug over placebo Effective posttraumatic stress disorder (PTSD) pharmacotherapy is needed. This 12-week randomized multicenter trial evaluated efficacy and safety of TNX-102 SL, a bedtime sublingual formulation of cyclobenzaprine, in patients with military-related PTSD randomized to TNX-102 SL 2.8 mg or 5.6 mg, or placebo. Primary analysis comparing change from baseline in Clinician-Administered PTSD Scale-5 score between 2.8 mg (n=90) and placebo (n=92) was not significant. Secondary analysis of 5.6 mg (n=49) vs placebo demonstrated a mean difference of -4.5 units, p=.05, or, accounting for missing data by multiple imputation, -5.0 units, p=.03. Clinician Global Impression – Improvement responder rate was greater in 5.6 mg than placebo (p=0.04), as was mean functional improvement in Sheehan Disability Scale social domain (p=.03) and trended in work domain (p=.05). Post-hoc analyses showed early sleep improvement predicted improvement in PTSD after 12 weeks for TNX-102 SL (p<.01), not for placebo. Most common administration site reaction in TNX-102 SL groups was oral hypoaesthesia (5.6 mg, 36%; 2.8 mg, 39%; placebo, 2%), while most common systemic adverse event was somnolence (5.6 mg, 16%; 2.8 mg, 12%; placebo, 6%). This provides preliminary evidence that TNX-102 SL 5.6 mg reduces PTSD symptoms, improves sleep and psychosocial function, and is well tolerated. Clinicaltrials.gov Identifier: NCT02277704 [ABSTRACT FROM AUTHOR]

The present work describes the performance of a new voltammetric sensor based on the modification of glassy carbon electrodes (GCE) with carbon black (CB) and botryosphaeran (BOT) (CB-BOT/GCE) for the electroanalytical determination of cyclobenzaprine. BOT is a fungal exocellular (1→3)(1→6)-β-ᴅ-glucan, which was used to improve the adherence of CB onto the surface of GCE. The electrochemical characterisation was performed by electrochemical impedance spectroscopy which showed an improvement in the transfer of electrons on the surface of the sensor developed in relation to the unmodified (bare) GCE. The voltammetric behaviour of cyclobenzaprine was studied using bare GCE, BOT/GCE, CB/GCE, and CB-BOT/GCE. All electrodes presented an oxidation peak (+ 1.0 V) for cyclobenzaprine, while the cyclobenzaprine peak intensity on CB-BOT/GCE was found to be 480% higher than the bare GCE. Through employing square-wave voltammetry, the analytical curve was found to be linear over the concentration range of 2.0 to 20.6 μmol L−1 (in 0.1 mol L−1 NaCl solution) with a detection limit (based on 3-sigma) of 0.63 μmol L−1. The developed electrochemical sensor exhibited excellent sensitivity and selectivity and was successfully applied for the voltammetric determination of cyclobenzaprine in pharmaceutical, biological, and environmental samples for the first time using the CB-BOT/GCE electrochemical sensing platform. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comprehensive oromucosal preformulation of cyclobenzaprine using esophageal mucosa as surrogate. • Comparison of standardized ex vivo permeation process vs artificial biomimetic membrane. • Classification of ex vivo permeation data to reported in vivo cyclobenzaprine data. • Assessment of impact of additional drugs on the permeability of cyclobenzaprine. As part of early drug development, preformulation studies are used to comprehensively explore the properties of new drugs. In particular, this includes the biopharmaceutical characterization and evaluation of impacting factors (e.g. excipients, microenvironmental conditions etc.) by permeation studies. To overcome the limitations of current studies, a novel standardized ex vivo procedure using esophageal mucosa as surrogate has been established successfully and applied to preformulation studies for oromucosal delivery of cyclobenzaprine hydrochloride, a tricyclic muscle relaxant with potential for psychopharmacotherapeutic use. By using the standardized ex vivo permeation process, a twofold enhancement of permeability (0.98 ± 0.16 to 1.96 ± 0.10 * 10-5 cm/s) was observed by adjustment and controlling of microenvironmental pH, empowering a targeted and effective development of sublingual formulations. Predictivity and suitability were superior compared to in vitro experiments using artificial biomimetic membranes, revealing a determination coefficient (R2) of 0.995 vs. 0.322 concerning pH-dependent permeability of cyclobenzaprine. In addition, diffusion properties were extensively examined (e.g. influence of mucosal thicknesses, tissue freezing etc.). The alignment of the study design regarding physiologically/clinically relevant conditions resulted in ex vivo data that allowed for the estimation of plasma AUC levels in the extend of reported in vivo ranges. [ABSTRACT FROM AUTHOR]

The reactivity of Cyproheptadine and Cyclobenzaprine in Pd-catalyzed arylation via C-H bond functionalizations was investigated. From Cyproheptadine using aryl bromides as aryl sources and 5 mol% of a palladium catalyst, the C10-arylated Cyproheptadine derivatives were regioselectively obtained. The highest yields were obtained with electron-rich aryl bromides, but the reaction tolerated useful functional groups on the aryl bromide such as dimethylamino, methoxy, hydroxyl, alkyl, aryl, fluoro, chloro and trifluoromethyl. Cyclobenzaprine was also reactive under the same reaction conditions. © 2019 Elsevier Science. All rights reserved. Unlabelled Image • First regioselective arylations at the C10-position of Cyproheptadine. • One step access to Cyproheptadine congeners. • Good functional group tolerance. • Air and moisture tolerant Pd-catalyst. [ABSTRACT FROM AUTHOR]