Celecoxib-tramadol co-crystal in patients with moderate-to-severe pain following bunionectomy with osteotomy: Secondary analyses by baseline pain intensity and use of rescue medication of a phase 3, randomized, double-blind, factorial, active- and placebo-controlled trial.

BACKGROUND: In the randomized, phase 3, SUSA-301 trial, celecoxib-tramadol co-crystal (CTC) provided significantly greater analgesia compared with celecoxib, tramadol, or placebo in adults with acute, moderate-to-severe, postoperative pain. This post hoc, secondary analysis further evaluated the use of rescue medication and the incidence of treatment-emergent adverse events (TEAEs). METHODS: Patients (N = 637) were randomized 2:2:2:1 to receive oral CTC 200 mg twice daily (BID; n = 184), tramadol 50 mg four times daily (QID; n = 183), celecoxib 100 mg BID (n = 181), or placebo QID (n = 89). Post hoc analyses were conducted on the use of rescue medications up to 4 and 48 h post-study drug dose, stratified by baseline pain intensity (moderate/severe), and on the incidence of TEAEs, stratified by rescue medication use. RESULTS: A significantly lower proportion of patients received any rescue medication within 4 h post-study dose with CTC (49.5%) versus tramadol (61.7%, p = 0.0178), celecoxib (65.2%, p = 0.0024), and placebo (75.3%, p = 0.0001); this was also seen for oxycodone use. Fewer patients in the CTC group received ≥3 doses of rescue medication compared with the other groups, irrespective of baseline pain intensity. In patients who did not receive opioid rescue medication, CTC was associated with a lower incidence of nausea and vomiting TEAEs versus tramadol alone. In patients who received rescue oxycodone, the incidence of nausea was similar in the CTC and tramadol groups, and higher versus celecoxib and placebo. CONCLUSION: Celecoxib-tramadol co-crystal was associated with reduced rescue medication use and an acceptable tolerability profile compared with tramadol or celecoxib alone in adults with acute, moderate-to-severe, postoperative pain.

Co-crystal of Tramadol-Celecoxib Versus Tramadol or Placebo for Acute Moderate-to-Severe Pain After Oral Surgery: Randomized, Double-Blind, Phase 3 Trial (STARDOM1).

INTRODUCTION: Co-crystal of tramadol-celecoxib (CTC) is the first analgesic co-crystal for acute pain. This completed phase 3 multicenter, double-blind trial assessed the efficacy and safety/tolerability of CTC in comparison with that of tramadol in the setting of moderate-to-severe pain up to 72 h after elective third molar extraction requiring bone removal. METHODS: Adults (n = 726) were assigned randomly to five groups (2:2:2:2:1): orally administered twice-daily CTC 100 mg (44 mg rac-tramadol hydrochloride/56 mg celecoxib; n = 164), 150 mg (66/84 mg; n = 160) or 200 mg (88/112 mg; n = 160); tramadol 100 mg four times daily (n = 159); or placebo four times daily (n = 83). Participants in CTC groups also received twice-daily placebo. The full analysis set included all participants who underwent randomization. The primary endpoint was the sum of pain intensity differences over 0 to 4 h (SPID0-4; visual analog scale). Key secondary endpoints included 4-h 50% responder and rescue medication use rates. Safety endpoints included adverse events (AEs), laboratory measures, and Opioid-Related Symptom Distress Scale (OR-SDS) score. RESULTS: All CTC doses were superior to placebo (P < 0.001) for primary and key secondary endpoints. All were superior to tramadol for SPID0-4 (analysis of covariance least squares mean differences [95% confidence interval]: - 37.1 [- 56.5, - 17.6], - 40.2 [- 59.7, - 20.6], and - 41.7 [- 61.2, - 22.2] for 100, 150, and 200 mg CTC, respectively; P < 0.001) and 4-h 50% responder rate. Four-hour 50% responder rates were 32.9% (CTC 100 mg), 33.8% (CTC 150 mg), 40.6% (CTC 200 mg), 20.1% (tramadol), and 7.2% (placebo). Rescue medication use was lower in the 100-mg (P = 0.013) and 200-mg (P = 0.003) CTC groups versus tramadol group. AE incidence and OR-SDS scores were highest for tramadol alone. CONCLUSIONS: CTC demonstrated superior pain relief compared with tramadol or placebo, as well as an improved benefit/risk profile versus tramadol. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT02982161; EudraCT number, 2016-000592-24.

Celecoxib-tramadol co-crystal in patients with moderate-to-severe pain following bunionectomy with osteotomy: A phase 3, randomized, double-blind, factorial, active- and placebo-controlled trial.

BACKGROUND: Celecoxib-tramadol co-crystal (CTC) is a first-in-class analgesic co-crystal of celecoxib and racemic tramadol with an improved pharmacologic profile, conferred by the co-crystal structure, compared with its active constituents administered alone/concomitantly. AIM: We evaluated CTC in moderate-to-severe acute postoperative pain. MATERIALS AND METHODS: This randomized, double-blind, factorial, active- and placebo-controlled phase 3 trial (NCT03108482) was conducted at 6 US clinical research centers. Adults with moderate-to-severe acute pain following bunionectomy with osteotomy were randomized to oral CTC (200 mg [112 mg celecoxib/88 mg rac-tramadol hydrochloride] every 12 h), tramadol (50 mg every 6 h), celecoxib (100 mg every 12 h), or placebo for 48 h. Patients, investigators, and personnel were blinded to assignment. The primary endpoint was the 0-48 h sum of pain intensity differences (SPID0-48) in all randomized patients. Pain intensity was assessed on a 0-10 numerical rating scale (NRS). Safety was analyzed in patients who received study medication. Funded by ESTEVE Pharmaceuticals. RESULTS: In 2017 (March to November), 1323 patients were screened and 637 randomized to CTC (n = 184), tramadol (n = 183), celecoxib (n = 181), or placebo (n = 89). Mean baseline NRS was 6.7 in all active groups. CTC had a significantly greater effect on SPID0-48 (least-squares mean: -139.1 [95% confidence interval: -151.8, -126.5]) than tramadol (-109.1 [-121.7, -96.4]; p < 0.001), celecoxib (-103.7 [-116.4, -91.0]; p < 0.001), or placebo (-74.6 [-92.5, -56.6]; p < 0.001). Total treatment-emergent adverse events (TEAEs) were 358 for CTC and 394 for tramadol. Drug-related TEAEs occurred in 37.7% patients in the CTC group, compared with 48.6% in the tramadol group. There were no serious TEAEs/deaths. CONCLUSION: CTC provided greater analgesia than comparable daily doses of tramadol and celecoxib, with similar tolerability to tramadol. CTC is approved in the United States.

Efficacy and safety of co-crystal of tramadol-celecoxib (CTC) in acute moderate-to-severe pain after abdominal hysterectomy: A randomized, double-blind, phase 3 trial (STARDOM2).

BACKGROUND: STARDOM2 is a randomized, double-blind, phase 3 trial evaluating the efficacy and safety of co-crystal of tramadol-celecoxib (CTC)-a first-in-class analgesic co-crystal comprising racemic tramadol hydrochloride and celecoxib in a supramolecular network that modifies their pharmacokinetic properties-for the management of acute postoperative pain (NCT03062644; EudraCT:2016-000593-38). METHODS: Patients with moderate-to-severe pain following abdominal hysterectomy were randomized 2:2:2:2:2:1 to oral CTC 100 mg (rac-tramadol hydrochloride 44 mg/celecoxib 56 mg) twice daily (BID); CTC 150 mg (66/84 mg) BID; CTC 200 mg (88/112 mg) BID; immediate-release tramadol 100 mg four times daily (QID); celecoxib 100 mg BID; or placebo, for 5 days. The primary endpoint was the sum of pain intensity differences over 0-4 h (SPID0-4 ). Key secondary endpoints were rescue medication use within 4 h, 50% response rate at 4 h, and safety/tolerability. RESULTS: Of 1355 patients enrolled, 1138 were randomized (full analysis set) and 1136 treated (safety analysis set). In the prespecified gatekeeping analysis of SPID0-4 , CTC 200 mg was not superior to tramadol but showed non-inferior efficacy (p < 0.001) that was sustained throughout the 120-h period, despite a 5-day cumulative tramadol administration of 880 mg with CTC 200 mg BID versus 2000 mg with tramadol 100 mg QID. Treatment-emergent adverse events (TEAEs) and severe TEAEs were less common with CTC 200 mg versus tramadol. Treatment-related TEAEs were 14.4% with CTC 200 mg and 23.6% with tramadol. CONCLUSIONS: Although the study did not meet its primary endpoint, CTC 200 mg showed a clinically relevant improvement in overall benefit/risk profile versus tramadol alone, with considerably lower cumulative opioid exposure. SIGNIFICANCE: In the randomized, double-blind, phase 3 STARDOM2 trial-in acute moderate-to-severe pain after abdominal hysterectomy-the novel co-crystal of tramadol-celecoxib (CTC) 200 mg BID was superior to placebo and non-inferior to tramadol 100 mg QID. Although superiority to tramadol was not reached, CTC 200 mg BID exposed patients to lower cumulative opioid (tramadol) doses than tramadol (100 mg QID) alone, with fewer treatment-emergent adverse events. CTC 200 mg thus has a clinically relevant improved benefit/risk profile compared with tramadol alone.

Celecoxib-tramadol co-crystal: A Randomized 4-Way Crossover Comparative Bioavailability Study.

PURPOSE: Celecoxib-tramadol co-crystal (CTC) is a first-in-class co-crystal of celecoxib and racemic tramadol. This Phase 1 bioavailability study compared single-dose pharmacokinetic (PK) parameters of CTC with those of the individual reference products from the United States, immediate-release celecoxib and tramadol, taken alone and simultaneously to determine their systemic exposure. METHODS: This was a single-center, randomized, single-dose, open-label, 4-period, 4-sequence, crossover study conducted in healthy subjects between October and December 2016. Study treatments included 200-mg CTC (equivalent to 112-mg celecoxib and 88-mg tramadol; Treatment-1); 100-mg tramadol (Treatment-2); 100-mg celecoxib (Treatment-3); and 100-mg celecoxib plus 100-mg tramadol (Treatment-4). The PK parameters of interest were Cmax, AUC0-T, and AUC0-∞, which were also calculated normalized to the dose. Tmax was only considered as supportive. The statistical analysis was based on a parametric analysis of variance model of the PK parameters; the two-sided 90% CI of the ratio of geometric mean values for the Cmax, AUC0-T, and AUC0-∞ was based on ln-transformed data, and Tmax was rank-transformed. FINDINGS: Thirty-six subjects aged 18 to 55 years (21 male subjects, 15 female subjects; mean age, 35 years) participated in the study. Celecoxib from CTC presented a lower Cmax, reduced AUCs, and a faster Tmax. The interference in celecoxib absorption when celecoxib and tramadol are administered together was minimized with the CTC. For Treatment-1, -3, and -4, celecoxib PK parameters were 259, 318, and 165 ng/mL (Cmax), respectively; 1930, 2348, and 1929 ng • h/mL (AUC0-T); and 1.5, 3.0, and 2.5 hours (Tmax). Tramadol and its active metabolite O-desmethyl tramadol from CTC presented lower Cmax and AUCs as well as a longer Tmax. Tramadol/O-desmethyl tramadol PK parameters for Treatment-1, -2, and -4 were 214/55, 305/78, and 312/78 ng/mL for Cmax; 2507/846, 2709/965, and 2888/1010 ng • h/mL for AUC0-T; and 3.0/4.0, 2.0/2.5, and 1.9/2.5 hours for Tmax. Reported adverse events (none unexpected) occurred more frequently with Treatment-2 and Treatment-4. IMPLICATIONS: The aim of this study was to compare the PK profile of the US-marketed tramadol and celecoxib products with CTC to determine their systemic exposure and to validate the dosing regimen for a subsequent pivotal factorial Phase 3study. PK parameters of each active component in CTC were favorably modified by co-crystallization and did not result in higher systemic exposure compared with US-marketed celecoxib, tramadol, and their concomitant administration. © 2021 Elsevier HS Journals, Inc.

Discovery of EST73502, a Dual µ-Opioid Receptor Agonist and σ1 Receptor Antagonist Clinical Candidate for the Treatment of Pain.

The synthesis and pharmacological activity of a new series of 4-alkyl-1-oxa-4,9-diazaspiro[5.5]undecane derivatives as potent dual ligands for the σ1 receptor (σ1R) and the µ-opioid receptor (MOR) are reported. A lead optimization program over the initial 4-aryl analogues provided 4-alkyl derivatives with the desired functionality and good selectivity and ADME profiles. Compound 14u (EST73502) showed MOR agonism and σ1R antagonism and a potent analgesic activity, comparable to the MOR agonist oxycodone in animal models of acute and chronic pain after single and repeated administration. Contrary to oxycodone, 14u produces analgesic activity with reduced opioid-induced relevant adverse events, like intestinal transit inhibition and naloxone-precipitated behavioral signs of opiate withdrawal. These results provide evidence that dual MOR agonism and σ1R antagonism may be a useful strategy for obtaining potent and safer analgesics and were the basis for the selection of 14u as a clinical candidate for the treatment of pain.

Co-crystals as a new approach to multimodal analgesia and the treatment of pain.

Pain is highly prevalent, but frequently untreated or under-treated, and health care professionals are faced with a range of treatment challenges. Multimodal therapy is recommended and can be achieved using open combinations (ie, concomitant administration) of individual agents, fixed-dose combinations (FDCs), or multimodal agents (ie, single agents with multiple mechanisms of action). Co-crystallization of active pharmaceutical ingredients (APIs) offers another approach, with the potential to provide drugs with unique properties and advantages for therapeutic applications compared to combinations. API-API co-crystals are single-entity forms that offer a unique possibility of improving the physicochemical properties of both constituent APIs, as well as permitting their synchronous release. Consequently, this may positively impact on their pharmacokinetic (PK) properties and profiles, providing a potential advantage over FDCs and translating into improved clinical efficacy and safety profiles. We report here a revision of the literature concerning API-API co-crystals for the treatment of pain. It becomes apparent that identifying APIs with complementary mechanisms of action that can be adequately co-crystallized in an appropriate molecular ratio applicable for therapeutic use is challenging. In addition, API-API co-crystals normally result in a mere increased exposure of an API without defined clinical benefits (since, to maintain the benefit-risk, the dose needs to be proportionally reduced to adjust for the increased exposure). An exception to this is the co-crystal of tramadol-celecoxib (CTC), that represents a unique concept in co-crystal technology. In CTC neither of its three active components that have complementary mechanisms of action (ie, the two enantiomers of tramadol and celecoxib) show increased exposure levels versus commercially available single-entity reference products, but rather show a change in their PK profile with potential clinical advantages. CTC is in Phase III clinical development for the treatment of pain.

A New Pharmacophore Model for the Design of Sigma-1 Ligands Validated on a Large Experimental Dataset.

The recent publication of the σ1R crystal structure is an important cornerstone for the derivation of more accurate activity prediction models. We report here a comparative study involving a set of more than 25,000 structures from our internal database that had been screened for σ1R affinity. Using the recently published crystal structure, 5HK1, two new pharmacophore models were generated. The first one, 5HK1-Ph.A, was obtained by an algorithm that identifies the most important receptor-ligand interactions including volume restrictions enforced by the atomic structure of the recognition site. The second, 5HK1-Ph.B, resulted from a manual edition of the first one by the fusion of two hydrophobic (HYD) features. Finally, we also docked the database using a high throughput docking technique and scored the resulting poses with seven different scoring functions. Statistical performance measures were obtained for the two models, comparing them with previously published σ1R pharmacophores (Hit Rate, sensitivity, specificity, and Receiver Operator Characteristic) and 5HK1-Ph.B emerged as the best one in discriminating between active and inactive compounds, with a ROC-AUC value above 0.8 and enrichment values above 3 at different fractions of screened samples. 5HK1-Ph.B also showed better results than the direct docking, which may be due to the rigidity of the crystal structure in the docking process (i.e., feature tolerances in the pharmacophore model). Additionally, the impact of the HYD interactions and the penalty for desolvating ligands with polar atoms may be not adequately captured by scoring functions, whereas HYD groups filling up such regions of the binding site are entailed in the pharmacophore model. Altogether, using annotated data from a large and diverse compound collection together with crystal structure information provides a sound basis for the generation and validation of predictive models to design new molecules.

Co-crystal of tramadol-celecoxib: preclinical and clinical evaluation of a novel analgesic.

INTRODUCTION: Pain management is a major unmet need due to the suboptimal efficacy and undesirable side effects of current analgesics. Multimodal therapies recruiting complementary mechanisms of action may help address this. Co-crystals incorporating two active pharmaceutical ingredients (APIs) constitute an innovative approach to multimodal therapy, particularly if modification of the physicochemical properties of constituent APIs can be translated into clinical benefits. AREAS COVERED: The preclinical and clinical profiles of Co-Crystal of Tramadol-Celecoxib (CTC), a novel API-API co-crystal (1:1 molecular ratio of rac-tramadol.hydrochloride and celecoxib) are described. EXPERT OPINION: CTC may provide a relevant addition to pain therapy due to its: i) unique co-crystal structure conferring differentiated intrinsic dissolution profiles on constituent APIs, ii) modified clinical pharmacokinetics (slower absorption of tramadol and faster absorption of celecoxib) compared with commercially available single-entity reference products (in agreement with modified dissolution rates), iii) superior benefit-risk ratio compared with reference products (suggested by preclinical synergistic antinociceptive effects, without potentiation of adverse effects), and iv) efficacy in a phase 2 trial of moderate to severe pain following extraction of ≥2 impacted third molars requiring bone removal, where CTC doses containing low doses of APIs exerted a significant effect. Phase 3 studies are currently ongoing.

The Effect of Food on Tramadol and Celecoxib Bioavailability Following Oral Administration of Co-Crystal of Tramadol-Celecoxib (CTC): A Randomised, Open-Label, Single-Dose, Crossover Study in Healthy Volunteers.

BACKGROUND AND OBJECTIVE: Co-Crystal of Tramadol-Celecoxib (CTC), in development for the treatment of moderate to severe acute pain, is a first-in-class co-crystal containing a 1:1 molecular ratio of two active pharmaceutical ingredients; rac-tramadol·HCl and celecoxib. This randomised, open-label, crossover study compared the bioavailability of both components after CTC administration under fed and fasting conditions. METHODS: Healthy adults received single doses of 200 mg CTC under both fed and fasting conditions (separated by a 7-day washout). Each dose of CTC was administered orally as two 100 mg tablets, each containing 44 mg tramadol·HCl and 56 mg celecoxib. In the fed condition, a high-fat, high-calorie meal [in line with recommendations by the US Food and Drug Administration (FDA)] was served 30 min before CTC administration. Tramadol, O-desmethyltramadol and celecoxib plasma concentrations were measured pre- and post-dose up to 48 h. Pharmacokinetic parameters were calculated using non-compartmental analysis. Safety was also assessed. RESULTS: Thirty-six subjects (18 female/18 male) received one or both doses of CTC; 33 provided evaluable pharmacokinetic data under fed and fasting conditions. For tramadol and O-desmethyltramadol, fed-to-fasting ratios of geometric least-squares means and corresponding 90% confidence interval (CI) values for maximum plasma concentration (Cmax) and extrapolated area under the plasma concentration-time curve to infinity (AUC∞) were within the pre-defined range for comparative bioavailability (80-125%). For celecoxib, Cmax and AUC∞ fed-to-fasting ratios (90% CIs) were outside this range, at 130.91% (116.98-146.49) and 129.34% (121.78-137.38), respectively. The safety profile of CTC was similar in fed and fasting conditions. CONCLUSIONS: As reported for standard-formulation celecoxib, food increased the bioavailability of celecoxib from single-dose CTC. Food had no effect on tramadol or O-desmethyltramadol bioavailability. CLINICAL TRIAL REGISTRATION NUMBER: 152052 (registered with the Therapeutic Products Directorate of Health Canada).

Co-crystal of Tramadol-Celecoxib in Patients with Moderate to Severe Acute Post-surgical Oral Pain: A Dose-Finding, Randomised, Double-Blind, Placebo- and Active-Controlled, Multicentre, Phase II Trial.

BACKGROUND: Co-crystal of tramadol-celecoxib (CTC), containing equimolar quantities of the active pharmaceutical ingredients (APIs) tramadol and celecoxib (100 mg CTC = 44 mg rac-tramadol hydrochloride and 56 mg celecoxib), is a novel API-API co-crystal for the treatment of pain. We aimed to establish the effective dose of CTC for treating acute pain following oral surgery. METHODS: A dose-finding, double-blind, randomised, placebo- and active-controlled, multicentre (nine Spanish hospitals), phase II study (EudraCT number: 2011-002778-21) was performed in male and female patients aged ≥ 18 years experiencing moderate to severe pain following extraction of two or more impacted third molars requiring bone removal. Eligible patients were randomised via a computer-generated list to receive one of six single-dose treatments (CTC 50, 100, 150, 200 mg; tramadol 100 mg; and placebo). The primary efficacy endpoint was the sum of pain intensity difference (SPID) over 8 h assessed in the per-protocol population. RESULTS: Between 10 February 2012 and 13 February 2013, 334 patients were randomised and received study treatment: 50 mg (n = 55), 100 mg (n = 53), 150 mg (n = 57), or 200 mg (n = 57) of CTC, 100 mg tramadol (n = 58), or placebo (n = 54). CTC 100, 150, and 200 mg showed significantly higher efficacy compared with placebo and/or tramadol in all measures: SPID (0-8 h) (mean [standard deviation]): - 90 (234), - 139 (227), - 173 (224), 71 (213), and 22 (228), respectively. The proportion of patients experiencing treatment-emergent adverse events was lower in the 50 (12.7% [n = 7]), 100 (11.3% [n = 6]), and 150 (15.8% [n = 9]) mg CTC groups, and similar in the 200 mg (29.8% [n = 17]) CTC group, compared with the tramadol group (29.3% [n = 17]), with nausea, dizziness, and vomiting the most frequent events. CONCLUSION: Significant improvement in the benefit-risk ratio was observed for CTC (doses ≥ 100 mg) over tramadol and placebo in the treatment of acute pain following oral surgery. FUNDING: Laboratorios del Dr. Esteve, S.A.U.

Efficacy of a Novel Sigma-1 Receptor Antagonist for Oxaliplatin-Induced Neuropathy: A Randomized, Double-Blind, Placebo-Controlled Phase IIa Clinical Trial.

This trial assessed the efficacy of MR309 (a novel selective sigma-1 receptor ligand previously developed as E-52862) in ameliorating oxaliplatin-induced peripheral neuropathy (oxaipn). A discontinuous regimen of MR309 (400 mg/day, 5 days per cycle) was tested in patients with colorectal cancer receiving FOLFOX in a phase II, randomized, double-blind, placebo-controlled, multicenter clinical trial. Outcome measures included changes in 24-week quantitative measures of thermal sensitivity and total neuropathy score. In total, 124 patients were randomized (1:1) to MR309 or placebo. Sixty-three (50.8%) patients withdrew prematurely before completing 12 planned oxaliplatin cycles. Premature withdrawal because of cancer progression was less frequent in the MR309 group (7.4% vs 25.0% with placebo; p = 0.054). MR309 significantly reduced cold pain threshold temperature [mean treatment effect difference (SE) vs placebo: 5.29 (1.60)°C; p = 0.001] and suprathreshold cold stimulus-evoked pain intensity [mean treatment effect difference: 1.24 (0.57) points; p = 0.032]. Total neuropathy score, health-related quality-of-life measures, and nerve-conduction parameters changed similarly in both arms, whereas the proportion of patients with severe chronic neuropathy (National Cancer Institute Common Terminology Criteria for Adverse Events ≥ 3) was significantly lower in the MR309 group (3.0% vs 18.2% with placebo; p = 0.046). The total amount of oxaliplatin delivered was greater in the active arm (1618.9 mg vs 1453.8 mg with placebo; p = 0.049). Overall, 19.0% of patients experienced at least 1 treatment-related adverse event (25.8% and 11.9% with MR309 and placebo, respectively). Intermittent treatment with MR309 was associated with reduced acute oxaipn and higher oxaliplatin exposure, and showed a potential neuroprotective role for chronic cumulative oxaipn. Furthermore, MR309 showed an acceptable safety profile.

Pharmacokinetics of multiple doses of co-crystal of tramadol-celecoxib: findings from a four-way randomized open-label phase I clinical trial.

AIM: We compared the pharmacokinetic (PK) profiles of co-crystal of tramadol-celecoxib (CTC) vs. each reference product (alone and in open combination) after single (first dose) and multiple dosing. METHODS: Healthy adults aged 18-50 years received, under fasted conditions, 15 twice-daily doses of the following treatments (separated by ≥14-day washout): 200 mg immediate-release (IR) CTC (equivalent to 88 mg tramadol and 112 mg celecoxib; treatment 1); 100 mg IR tramadol (treatment 2), 100 mg celecoxib (treatment 3); and 100 mg IR tramadol and 100 mg celecoxib (treatment 4). The treatment sequence was assigned by computer-generated randomization. PK parameters were calculated using non-compartmental analysis. Parameters for CTC were adjusted according to reference product dose. RESULTS: A total of 30 subjects (20 males, mean age 35 years) were included. Multiple-dose tramadol PK parameters for treatments 1, 2 and 4, respectively, were 551, 632 and 661 ng ml-1 [mean maximum plasma concentration (Cmax )]; 4796, 4990 and 5284 ng h ml-1 (area under the plasma concentration-time curve over the dosing interval at steady state); and 3.0, 2.0 and 2.0 h (median time to Cmax at steady state). For treatments 1, 3 and 4, multiple-dose celecoxib PK parameters were 445, 536 and 396 ng ml-1 ; 2803, 3366 and 2897 ng h ml-1 ; and 2.0, 2.0 and 3.0 h. Single-dose findings were consistent with multiple-dose data. Types of adverse events were consistent with known reference product safety profiles. CONCLUSION: After single (first dose) and multiple dosing, PK parameters for each active pharmaceutical ingredient in CTC were modified by co-crystallization compared with reference products alone or in open combination.

Single-dose pharmacokinetics of co-crystal of tramadol-celecoxib: Results of a four-way randomized open-label phase I clinical trial in healthy subjects.

AIMS: Co-crystal of tramadol-celecoxib (CTC) is a novel co-crystal molecule containing two active pharmaceutical ingredients under development by Esteve (E-58425) and Mundipharma Research (MR308). This Phase I study compared single-dose pharmacokinetics (PK) of CTC with those of the individual reference products [immediate-release (IR) tramadol and celecoxib] alone and in open combination. METHODS: Healthy adults aged 18-55 years were orally administered four treatments under fasted conditions (separated by 7-day wash-out period): 200 mg IR CTC (equivalent to 88 mg tramadol and 112 mg celecoxib; Treatment 1); 100 mg IR tramadol (Treatment 2); 100 mg celecoxib (Treatment 3); and 100 mg IR tramadol and 100 mg celecoxib (Treatment 4). Treatment sequence was assigned using computer-generated randomization. PK parameters were calculated using noncompartmental analysis with parameters for CTC adjusted according to reference product dose (100 mg). RESULTS: Thirty-six subjects (28 male, mean age 36 years) participated. Tramadol PK parameters for Treatments-1, -2 and -4, respectively, were 263, 346 and 349 ng ml-1 (mean maximum plasma concentration); 3039, 2979 and 3119 ng h ml-1 (mean cumulative area under the plasma concentration-time curve); and 2.7, 1.8 and 1.8 h (median time to maximum plasma concentration). For Treatments 1, 3 and 4, the respective celecoxib PK parameters were 313, 449 and 284 ng ml-1 ; 2183, 3093 and 2856 ng h ml-1 ; and 1.5, 2.3 and 3.0 h. No unexpected adverse events were reported. CONCLUSION: PK parameters of each API in CTC were modified by co-crystallization compared with marketed formulations of tramadol, celecoxib, and their open combination.

Sigma-1 Receptor and Pain.

There is a critical need for new analgesics acting through new mechanisms of action, which could increase the efficacy respect to existing therapies and/or reduce their unwanted effects. Current preclinical evidence supports the modulatory role of the sigma-1 receptor (σ1R) in nociception, mainly based on the pain-attenuated phenotype of σ1R knockout mice and on the antinociceptive effect exerted by σ1R antagonists on pain of different etiology, very consistently in neuropathic pain, but also in nociceptive, inflammatory, and visceral pain. σ1R is highly expressed in different pain areas of the CNS and the periphery, particularly dorsal root ganglia (DRG), and interacts and modulates the functionality of different receptors and ion channels. Accordingly, antinociceptive effects of σ1R antagonists both acting alone and in combination with other analgesics have been reported at both central and peripheral sites. At the central level, behavioral, electrophysiological, neurochemical, and molecular findings support a role for σ1R antagonists in inhibiting augmented excitability secondary to sustained afferent input. Moreover, the involvement of σ1R in mechanisms regulating pain at the periphery has been recently confirmed. Unlike opioids, σ1R antagonists do not modify normal sensory mechanical and thermal sensitivity thresholds but they exert antihypersensitivity effects (antihyperalgesic and antiallodynic) in sensitizing conditions, enabling the reversal of nociceptive thresholds back to normal values. These are distinctive features allowing σ1R antagonists to exert a modulatory effect specifically in pathophysiological conditions such as chronic pain.

Pharmacological Modulation of the Sigma 1 Receptor and the Treatment of Pain.

There is a critical need for new analgesics acting through new mechanisms of action, which could increase the efficacy with respect to existing therapies and reduce their unwanted effects. Current preclinical evidence supports the modulatory role of sigma-1 receptors (σ1R) in nociception, mainly based on the pain-attenuated phenotype of σ1R knockout mice and on the antinociceptive effect exerted by σ1R antagonists on pains of different etiologies. σ1R is highly expressed in different pain areas of the CNS and the periphery (particularly dorsal root ganglia), and interacts and modulates the functionality of different receptors and ion channels . The antagonism of σ1R leads to decreased amplification of pain signaling within the spinal cord (central sensitization), but recent data also support a role at the periphery. σ1R antagonists have consistently demonstrated efficacy in neuropathic pain , but also in other types of pain including inflammatory, orofacial, visceral, and post-operative pain. Apart from acting alone, when combined with opioids, σ1R antagonists enhance opioid analgesia but not opioid-induced unwanted effects. Interestingly, unlike opioids, σ1R antagonists do not modify normal sensory mechanical and thermal sensitivity thresholds but they exert antihypersensitive effects in sensitizing conditions, enabling the reversal of nociceptive thresholds back to normal values. Accordingly, σ1R antagonists are not strictly analgesics; they are antiallodynic and antihyperalgesic drugs acting when the system is sensitized following prolonged noxious stimulation or persistent abnormal afferent input (e.g., secondary to nerve injury). These are distinctive features allowing σ1R antagonists to exert a modulatory effect specifically in pathophysiological conditions such as chronic pain .

Considerations for target validation and industrial approaches.

Target validation in health and disease integrates the modulation of a certain molecular target with an expected biological/biochemical/physiological or pathophysiological response or effect. The current state-of-the-art in target validation requires the interface of multiple complementary approaches and technologies to define the mechanistic connectivity between a molecular target and underlying micro- and macrobiotic processes. Target validation also represents the basis for "drug target validation" with focus on therapeutic applications. The concepts of "target validation" and "drug-based therapeutic intervention" continue to coevolve as new classes of therapeutic agents and delivery systems emerge and enable us to target or modulate previously inaccessible molecular entities.

Diarylacetylene piperidinyl amides as novel anxiolytics.

N-Phenyl-2-[1-[3-(2-pyridinylethynyl)benzoyl]-4-piperidine]acetamide (9) and related piperidine acetamide derivatives have good oral activity in the elevated plus maze, an animal model predictive of clinical efficacy for the treatment of anxiety. Modest affinity was observed for the neurokinin NK-1 and 2 receptors, which are known to be involved in the regulation of mood and emotion.

Integrated expressional analysis: application to the drug discovery process.

Microarray technology enables high-throughput testing of gene expression to investigate various neuroscience related questions. This in turn creates a demand for scalable methods to confirm microarray results and the opportunity to use this information to discover and test novel pathways and therapeutic applications. Discovery of new central nervous system (CNS) treatments requires a comprehensive understanding of multiple aspects including the biology of a target, the pathophysiology of a disease/disorder, and the selection of successful lead compounds as well as efficient biomarker and drug disposition strategies such as absorption (how a drug is absorbed), distribution (how a drug spreads through an organism), metabolism (chemical conversion of a drug, if any, and into which substances), and elimination (how is a drug eliminated) (ADME). Understanding of the toxicity is also of paramount importance. These approaches, in turn, require novel high-content integrative assay technologies that provide thorough information about changes in cell biology. To increase efficiency of profiling, characterization, and validation, we established a new screening strategy that combines high-content image-based testing on Array Scan (Cellomics) with a confocal system and the multiplexed TaqMan RT-PCR method for quantitative mRNA expression analysis. This approach could serve as an interface between high-throughput microarray testing and specific application of markers discovered in the course of a microarray experiment. Markers could pinpoint activation or inhibition of a molecular pathway related, for instance, to neuronal viability. We demonstrate the successful testing of the same cell population in an image-based translocational assay followed by poly(A) mRNA capture and multiplexed single tube RT-PCR. In addition, Ciphergen ProteinChip analysis can be performed on the supernatant, thus allowing significant complementarity in the data output and interpretation by also including the capture and initial analysis of proteins in the integrative approach presented. We have determined various conditions including the number of cells, RT and PCR optimization, which are necessary for successful detection and consequent assay integration. We also show the successful convergence of various different approaches and multiplexing of different targets within a single real-time PCR tube. This novel integrative technological approach has utility for CNS drug discovery, target and biomarker identification, selection and characterization as well as for the study of toxicity- and adverse event-associated molecular mechanisms.

Activity-dependent neurotrophic factor-9 and NAP promote neurite outgrowth in rat hippocampal and cortical cultures.

Activity-dependent neurotrophic factor (ADNF) is a novel, femtomolar-acting, glial-derived polypeptide (14 kDa) known to protect neurons from a variety of toxic insults. The active site for ADNF function is localized to a 9-amino-acid stretch (SALLRSIPA; ADNF-9). A few years later, a novel ADNF-9-like active peptide (NAPVSIPQ or NAP) was identified and shown to be expressed in the CNS and exhibit an activity profile similar to ADNF-9. Such studies suggest that ADNF-9 and NAP might function like other known neurotrophins and play a role in neural development and maintenance. The purpose of the present studies was to determine if ADNF-9 or NAP affects neurite outgrowth and synaptogenesis in rat hippocampal and cortical cultures. Using MAP2-FITC immunofluorescent labeling, we found that ADNF-9 and NAP promoted neurite outgrowth in a concentration-dependent manner, with maximal activity observed at femtomolar concentrations. Both peptides stimulated robust outgrowth in hippocampal cells (approximately 150% of control; p < 0.01) with a modest effect on cortical cells (approximately 20% of control; p < 0.05) similar to other known growth factors. However, the outgrowth-promoting effect was abolished in the absence of serum, suggesting that soluble factors might be necessary for the neurotrophic activity. Finally, we found that ADNF-9 and NAP increased synaptophysin expression in both rat hippocampal and cortical cultures. These results suggest that ADNF-9 and NAP might contribute to neuronal plasticity associated with development and repair after injury.