Improving Study Conduct and Data Quality in Clinical Trials of Chronic Pain Treatments: IMMPACT Recommendations

The estimated probability of progressing from phase 3 analgesic clinical trials to regulatory approval is approximately 57%, suggesting that a considerable number of treatments with phase 2 trial results deemed sufficiently successful to progress to phase 3 do not yield positive phase 3 results. Deficiencies in the quality of clinical trial conduct could account for some of this failure. An Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting was convened to identify potential areas for improvement in trial conduct in order to improve assay sensitivity (ie, ability of trials to detect a true treatment effect). We present recommendations based on presentations and discussions at the meeting, literature reviews, and iterative revisions of this article. The recommendations relate to the following areas: 1) study design (ie, to promote feasibility), 2) site selection and staff training, 3) participant selection and training, 4) treatment adherence, 5) data collection, and 6) data and study monitoring. Implementation of these recommendations may improve the quality of clinical trial data and thus the validity and assay sensitivity of clinical trials. Future research regarding the effects of these strategies will help identify the most efficient use of resources for conducting high quality clinical trials. PERSPECTIVE: Every effort should be made to optimize the quality of clinical trial data. This manuscript discusses considerations to improve conduct of pain clinical trials based on research in multiple medical fields and the expert consensus of pain researchers and stakeholders from academia, regulatory agencies, and industry.

Reductions in reported deaths following the introduction of extended-release oxycodone (OxyContin) with an abuse-deterrent formulation

Purpose

Abuse of opioid analgesics for their psychoactive effects is associated with a large number of fatalities. The effect of making opioid tablets harder to crush/dissolve on opioid-related fatalities has not been assessed. The objective of this study was to assess the impact of introducing extended-release oxycodone (ERO [OxyContin®]) tablets containing physicochemical barriers to crushing/dissolving (reformulated ERO) on deaths reported to the manufacturer.

Methods

All spontaneous adverse event reports of death in the US reported to the manufacturer between 3Q2009 and 3Q2013 involving ERO were used. The mean numbers of deaths/quarter in the 3 years after reformulated ERO introduction were compared with the year before. Changes in the slope of trends in deaths were assessed using spline regression. Comparison groups consisted of non-fatal reports involving ERO and fatality reports involving ER morphine.

Results

Reports of death decreased 82% (95% CI: −89, −73) from the year before to the third year after (131 to 23 deaths per year) reformulation; overdose death reports decreased 87% (95% CI: −93, −78) and overdose deaths with mention of abuse-related behavior decreased 86% (95% CI:−92, −75). In contrast, non-fatal ERO reports did not decrease post-reformulation, and reported ER morphine fatalities remained unchanged. The ratio of ERO fatalities to all oxycodone fatalities decreased from 21% to 8% in the year pre-reformulation to the second year post-reformulation.

Conclusions

These findings, when considered in the context of previously published studies using other surveillance systems, suggest that the abuse-deterrent characteristics of reformulated ERO have decreased the fatalities associated with its misuse/abuse. © 2014 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons, Ltd.

A randomized, placebo-controlled, double-blinded, parallel-group, 5-week study of buprenorphine transdermal system in adults with osteoarthritis

BACKGROUND

This multicenter, parallel-group, 35-day study in adults with osteoarthritis (OA) pain evaluated the analgesic efficacy and safety of buprenorphine transdermal system (BTDS) designed for 7-day wear.

METHODS

Patients with OA pain inadequately controlled with nonsteroidal antiinflammatory drugs or patients who had taken opioids for OA pain within the past year entered a 7-day run-in period during which they took ibuprofen only. Patients with pain > or = on a 0-10 scale had their ibuprofen discontinued and were randomized into a 28-day double-blinded period to receive either BTDS at 1 of 3 dose levels (5, 10, or 20 microg/b) or placebo. Doses were titrated to effectiveness over a period of 21 days and maintained for 7 days. No rescue medication was allowed during the study. The primary efficacy measure was the proportion of patients who achieved treatment success, defined as a patient satisfaction score of good, very good, or excellent (on day 28 or at early discontinuation) for those who did not discontinue due to ineffective treatment.

RESULTS

More BTDS-treated patients experienced treatment success than placebo TDS-treated patients (44 percent and 32 percent; odds ratio = 1.66, p = 0.036). Fewer patients taking BTDS titrated to the highest dose compared with placebo (p < 0.05). There were two serious adverse events (both in the placebo group) and no deaths. The most common (> or =5 percent) adverse events reported in BTDS-treated patients were nausea, headache, dizziness, somnolence, application site pruritus, and vomiting.

CONCLUSION

Compared with placebo, BTDS treatment was effective in treating patients with moderate to severe pain due to OA of the knee or hip. BTDS was well-tolerated.

Proton-induced physicochemical calcium release from ceramic apatite disks

When bone is cultured in acid medium there is net calcium efflux (JCa) and proton influx (JH) relative to the mineral. The acid medium appears to induce physicochemical mineral dissolution as well as cell-mediated bone resorption. To determine the independent effect of acid medium on physicochemical dissolution, we utilized cell-free synthetic ceramic apatite (CAP) disks, which contain carbonate (5.5%) in an apatite structure chemically similar to mammalian bone. CAP disks were cultured in control (Ctl, pH approximately equal to 7.44) or acid (Met, pH approximately equal to 7.11) medium for 48 h and compared to similarly treated neonatal (4-6 days old) mouse calvariae. Medium was changed and analyzed at 3, 24, and 48 h. At 3, 24, and 48 h there was significantly greater JCa from the CAP disks and calvariae incubated in Met compared to Ctl; over the entire 48 h time period there was a greater progressive increase in JCa from the CAP disks than the calvariae incubated in Met. There was no significant JCa at 3, 24, or 48 h from CAP disks or calvariae incubated in Ctl. At 3 h there was significantly greater JH into the CAP disks and calvariae incubated in Met compared to Ctl; JH was greater into the CAP disks than the calvariae. Utilizing a synthetic model of bone mineral we demonstrated that acid medium induces physicochemical calcium efflux and proton influx relative to the mineral.

Increased urinary saturation and kidney calcium content in genetic hypercalciuric rats

We have established a colony of genetic hypercalciuric (IH) rats as a model of idiopathic hypercalciuria in humans. To test the hypothesis that hypercalciuria can cause crystallization in kidneys through increased supersaturation, in the absence of confounding effects of diet and whatever complex inhibitor disorders underlay stone disease, we fed males and females of the 21st generation of IH rats 13 g per day of a low calcium (LCD, 0.02% Ca), followed by a normal calcium (NCD, 0.6% Ca) and then a high calcium (HCD, 1.2% Ca) diet, each for seven days. During the last 24 hours of each period complete urine collections were obtained and analyzed for all substances known to affect urinary calcium oxalate (CaOx) and brushite (CaHPO4) supersaturation. Relative supersaturation with respect to the solid phases of CaOx and CaHPO4 were then calculated. Compared to same gender controls (Ctl) urine calcium excretion was higher in the female IH rats on all diets and in the male IH rats on NCD and HCD. The female and male IH rats on NCD and HCD were supersaturated with respect to CaOx; however, the male and female Ctl were supersaturated with respect CaOx only on HCD. The female IH rats on NCD and HCD and the male IH rats on NCD were supersaturated with respect to CaHPO4; however, neither the male nor female Ctl rats were supersaturated with respect to CaHPO4 on any diet. On NCD and HCD urine supersaturation with respect to CaHPO4 by females exceeded that of males.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased bone carbonate content in response to metabolic, but not respiratory, acidosis

In vitro cultured neonatal mouse calvariae release calcium and buffer the medium proton concentration in response to a decrease in the medium pH caused by a reduction in bicarbonate concentration ([HCO3-]), a model of metabolic acidosis, but not to an equivalent decrease in pH caused by an increase in the partial pressure of carbon dioxide (PCO2), a model of respiratory acidosis. We have postulated that the medium is in equilibrium with the carbonated apatite in bone. To determine whether bone carbonate is depleted during models of acidosis, we cultured calvariae in control medium (pH approximately 7.4, PCO2 approximately 43, [HCO3-] approximately 26) or in medium in which the pH was equivalently reduced by either a decrease in [HCO3-] (metabolic acidosis, pH approximately 7.1, [HCO3-] approximately 13) or an increase in PCO2 (respiratory acidosis, pH approximately 7.1, PCO2 approximately 86) and determined net calcium flux (JCa) and bone carbonate content. We found that compared with control, after 3, 24, and 48 h there was a decrease in bone carbonate content during metabolic but not during respiratory acidosis. Compared with control, at 3 h JCa increased with both respiratory and metabolic acidosis; however, at 24 and 48 h JCa increased only with metabolic acidosis. JCa was correlated inversely with percent bone carbonate content in control and metabolic acidosis at all time periods studied (r = -0.809, n = 23, P < 0.001). Thus a model of metabolic acidosis appears to increase JCa from bone, perhaps due to the low [HCO3-] inducing bone carbonate dissolution.(ABSTRACT TRUNCATED AT 250 WORDS)

Physicochemical effects of acidosis on bone calcium flux and surface ion composition

Net calcium flux (JCa) from bone in vitro is pH dependent. When pH falls below 7.40, through a reduction in [HCO3-], there is both physicochemical and cell-mediated JCa. To characterize the physicochemical effect of acidosis on bone we inhibited the bone-resorbing cells (osteoclasts) with the specific inhibitor calcitonin and studied the effect of acidosis on JCa and bone ion composition using an analytic high-resolution scanning ion microprobe. Neonatal mouse calvariae were cultured for 48 h in physiologically neutral pH medium (Ntl, pH = 7.41, [HCO3-] = 25 nM) or in medium that modeled metabolic acidosis (Met, pH = 7.10, [HCO3-] = 12), each with or without calcitonin (CT, 3 x 10(-9) M). There was net calcium efflux in Ntl (JCa = 631 +/- 36 nmol per bone per 48 h), which increased in Met (1019 +/- 53, p < 0.01); CT inhibited JCa in Ntl (-54 +/- 11, p < 0.01 versus Ntl), which increased in Met (197 +/- 15, p < 0.01 versus Ntl + CT). In the presence of CT the increase in JCa in Met versus Ntl represents physiochemical bone dissolution. The Ntl bone surface (approximately 2 nm in depth) was rich in Na compared to Ca (Na/Ca = 11.9, count/s of detected secondary ions), which fell in Met (Na/Ca = 6.0, p < 0.05); CT caused a further reduction of Na/Ca (3.1, p < 0.01 versus Ntl and versus Met), which was not altered in Met (2.6, p < 0.05 versus Ntl + CT).(ABSTRACT TRUNCATED AT 250 WORDS)

Response of genetic hypercalciuric rats to a low calcium diet

A fundamental mechanism for hypercalciuria in genetic hypercalciuric rats appears due to a primary increase in intestinal calcium absorption. However previous studies could not exclude additional mechanisms to account for the hypercalciuria. To determine if enhanced bone mineral dissolution either as a primary abnormality or secondary to a defect in renal tubule calcium reabsorption is responsible for a component of the augmented calcium excretion we studied rats continually inbred for hypercalciuria. Nineteenth generation adult female idiopathic hypercalciuric (IH) and non-inbred control (Ctl) rats were fed 13 g/day of a normal calcium diet (0.6% calcium, NCD) for 10 days. Urine calcium excretion over the last seven days was greater in IH (34 +/- 2 mg/7 day) than in Ctl (2.9 +/- 0.3, P < 0.01) rats. Some rats in each group were continued on the same diet while others were fed a low calcium diet (0.02% calcium, LCD) for an additional 10 days; balance measurements were made over the final seven days. With LCD, urine calcium excretion was approximately 8-fold higher in IH compared to Ctl (13 +/- 2 mg/7 day vs. 1.6 +/- 0.1, IH vs. Ctl, respectively, P < 0.01). In IH rats percent calcium absorption was greater (59 +/- 3% vs. 45 +/- 3, IH vs. Ctl, P < 0.01), however calcium retention was negative (-1.9 +/- 2.0 mg/7 day vs. 6.5 +/- 0.5, IH vs. Ctl, P < 0.01) compared to Ctl rats. The fall in urine calcium excretion when IH rats are fed LCD indicates that enhanced intestinal calcium absorption is a primary mechanism of the hypercalciuria.(ABSTRACT TRUNCATED AT 250 WORDS)

Critical role of bicarbonate in calcium release from bone

Calcium release from cultured bone is pH dependent; net calcium flux (JCa) from bone increases with decreasing pH. At a similar decrement in pH there is greater JCa when acidosis is produced by a low medium bicarbonate concentration ([HCO3-]), a model of metabolic acidosis (Met), compared with an increased medium PCO2, a model of respiratory acidosis (Resp). To separate the role of [HCO3-] from that of pH in inducing JCa we cultured calvariae for 3 h under three different neutral (pH approximately 7.4) isohydric environments [control (Ctl), fully compensated Met (C-Met), or fully compensated Resp (C-Resp)] and two different acid (pH approximately 7.1) isohydric environments (Met or Resp). During neutral pH (Ctl, C-Met, and C-Resp) there was JCa from bone during C-Met (decreased [HCO3-]), no net flux during Ctl (normal [HCO3-]), and JCa into bone during C-Resp (increased [HCO3-]); and JCa was correlated inversely with [HCO3-] (r = -0.824, n = 36, P less than 0.001). During acid pH there was greater JCa from bone during Met (decreased [HCO3-]) than during Resp (normal [HCO3-]); and JCa was again correlated inversely with [HCO3-] (r = -0.848, n = 22, P less than 0.001). JCa from bone during Met and Resp was greater than C-Met and C-Resp, respectively. The addition of the osteoclastic inhibitor salmon calcitonin did not alter the relative JCa results. Thus at a constant pH the magnitude of JCa from cultured neonatal mouse calvariae appears dependent on the [HCO3-]; the lower the [HCO3-], the greater the calcium efflux.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis inhibits osteoblastic and stimulates osteoclastic activity in vitro

Metabolic acidosis induces net calcium flux (JCa) from cultured neonatal mouse calvariae through physicochemical and cell-mediated mechanisms. To determine the role of osteoblasts in acid-induced JCa, collagen synthesis and alkaline phosphatase activity were assessed in calvariae incubated in reduced pH and bicarbonate medium, a model of metabolic acidosis (Met), and compared with controls (Ctl). Collagen synthesis fell from 30.5 +/- 1.1 in Ctl to 25.1 +/- 0.4% with Met, and alkaline phosphatase decreased from 403 +/- 25 in Ctl to 298 +/- 21 nmol Pi.min-1.mg protein-1 with Met. During acidosis JCa was correlated inversely with percent collagen synthesis (r = -0.743, n = 11, P = 0.009) and with alkaline phosphatase activity (r = -0.453, n = 22, P = 0.034). To determine the role of osteoclasts in acid-induced JCa, osteoclastic beta-glucuronidase activity was determined in Ctl and Met in the absence or presence of the osteoclastic inhibitor calcitonin (CT, 3 x 10(-9) M). Met increased beta-glucuronidase (5.9 +/- 0.2) compared with Ctl (4.6 +/- 0.3 micrograms phenolphthalein released.bone-1.h-1), whereas CT inhibited beta-glucuronidase in both Ctl and Met (3.1 +/- 0.2 and 3.5 +/- 0.3, respectively). During acidosis JCa was correlated directly with beta-glucuronidase activity (r = 0.683, n = 42, P less than 0.001). Thus the cell-mediated component of JCa during acidosis in vitro appears to result from a combination of inhibited osteoblastic and stimulated osteoclastic activity.

Greater unidirectional calcium efflux from bone during metabolic, compared with respiratory, acidosis

There is a smaller net calcium efflux from bone in vitro during respiratory (increased PCO2) than metabolic (decreased [HCO3-] acidosis. This could be due to the elevated PCO2, which would lessen the driving force for mineral dissolution and increase the driving force for mineralization with respect to carbonated apatite in the bone mineral. To test this hypothesis, we injected neonatal mice with 45Ca and dissected the radiolabeled calvariae 24 h later. The live calvariae were then cultured for 24 h under conditions simulating respiratory acidosis (Resp, pH = 7.225 +/- 0.003, PCO2 = 87.5 +/- 0.1 mmHg), severe respiratory acidosis (SResp, pH = 7.072 +/- 0.004, PCO2 = 103.0 +/- 0.5 mmHg), metabolic acidosis (Met, pH = 7.212 +/- 0.003, HCO3- = 15.5 +/- 0.1 meq/l), or normal acid-base status (Ctl, pH = 7.452 +/- 0.003, PCO2 = 40.0 +/- 0.2 mmHg, HCO3- = 27.8 +/- 0.2 meq/l) and bidirectional net calcium flux (JCa) and unidirectional 45Ca release were determined. There was greater JCa from bone during Met than Resp, and JCa was not different from Met during SResp despite the latter having a significantly lower pH. There was greater unidirectional 45Ca release from bone during Met than Resp, SResp, or Ctl. There was a similar direct correlation between JCa and 45Ca efflux in the respiratory and metabolic groups. However, when calvarial osteoclast activity was inhibited with calcitonin,although there was again greater JCa and 45Ca release with a metabolic compared with respiratory acidosis, there was a greater proportion of 45Ca release than JCa from bone.(ABSTRACT TRUNCATED AT 250 WORDS)