Analgesic efficacy and safety of a novel injectable formulation of diclofenac compared with intravenous ketorolac and placebo after orthopedic surgery: a multicenter, randomized, double-blinded, multiple-dose trial

Safety and Efficacy of Perioperative Intravenous Meloxicam for Moderate-to-Severe Pain Management in Total Knee Arthroplasty: A Randomized Clinical Trial

Objective

To evaluate the effect of perioperative meloxicam IV 30 mg on opioid consumption in primary total knee arthroplasty (TKA).

Design

Multicenter, randomized, double-blind, placebo-controlled trial.

Subjects

In total, 181 adults undergoing elective primary TKA.

Methods

Subjects received meloxicam 30 mg or placebo via an IV bolus every 24 hours, the first dose administered prior to surgery as part of a multimodal pain management protocol. The primary efficacy parameter was total opioid use from end of surgery through 24 hours.

Results

Meloxicam IV was associated with less opioid use versus placebo during the 24 hours after surgery (18.9 ± 1.32 vs 27.7 ± 1.37 mg IV morphine equivalent dose; P < 0.001) and was superior to placebo on secondary endpoints, including summed pain intensity (first dose to 24 hours postdosing, first dose to first assisted ambulation, and first dose to discharge) and opioid use (48–72 hrs., 0–48 hrs., 0–72 hrs., hour 0 to end of treatment, and the first 24 hours after discharge). Adverse events (AEs) were reported for 69.9% and 92.0% of the meloxicam IV and placebo groups, respectively; the most common AEs were nausea (40% vs. 59%), vomiting (16% vs 22%), hypotension (14% vs 15%), pruritus (15% vs 11%), and constipation (11% vs 13%).

Conclusions

Perioperative meloxicam IV 30 mg as part of a multimodal analgesic regimen for elective primary TKA reduced opioid consumption in the 24-hour period after surgery versus placebo and was associated with a lower incidence of AEs typically associated with opioid use.

Efficacy of non-opioid analgesics to control postoperative pain: a network meta-analysis

Background

The aim of this network meta-analysis (NMA) was to evaluate the safety and efficacy of intravenous (IV) Meloxicam 30 mg (MIV), an investigational non-steroidal anti-inflammatory drug (NSAID), and certain other IV non-opioid analgesics for moderate-severe acute postoperative pain.

Methods

We searched PubMed and CENTRAL for Randomized Controlled Trials (RCT) (years 2000–2019, adult human subjects) of IV non-opioid analgesics (IV NSAIDs or IV Acetaminophen) used to treat acute pain after abdominal, hysterectomy, bunionectomy or orthopedic procedures. A Bayesian NMA was conducted in R to rank treatments based on the standardized mean differences in sum of pain intensity difference from baseline up to 24 h postoperatively (sum of pain intensity difference: SPID 24). The probability and the cumulative probability of rank for each treatment were calculated, and the surface under the cumulative ranking curve (SUCRA) was applied to distinguish treatments on the basis of their outcomes such that higher SUCRA values indicate better outcomes. The study protocol was prospectively registered with by PROSPERO (CRD42019117360).

Results

Out of 2313 screened studies, 27 studies with 36 comparative observations were included, producing a treatment network that included the four non-opioid IV pain medications of interest (MIV, ketorolac, acetaminophen, and ibuprofen). MIV was associated with the largest SPID 24 for all procedure categories and comparators. The SUCRA ranking table indicated that MIV had the highest probability for the most effective treatment for abdominal (89.5%), bunionectomy (100%), and hysterectomy (99.8%). MIV was associated with significantly less MME utilization versus all comparators for abdominal procedures, hysterectomy, and versus acetaminophen in orthopedic procedures. Elsewhere MME utilization outcomes for MIV were largely equivalent or nominally better than other comparators. Odds of ORADEs were significantly higher for all comparators vs MIV for orthopedic (gastrointestinal) and hysterectomy (respiratory).

Conclusions

MIV 30 mg may provide better pain reduction with similar or better safety compared to other approved IV non-opioid analgesics. Caution is warranted in interpreting these results as all comparisons involving MIV were indirect.

Single-dose intravenous diclofenac for acute postoperative pain in adults

BACKGROUND

Postoperative administration of non-steroidal anti-inflammatory drugs (NSAIDs) reduces patient opioid requirements and, in turn, reduces the incidence and severity of opioid-induced adverse events (AEs).

OBJECTIVES

To assess the analgesic efficacy and adverse effects of single-dose intravenous diclofenac, compared with placebo or an active comparator, for moderate to severe postoperative pain in adults.

SEARCH METHODS

We searched the following databases without language restrictions: the Cochrane Central Register of Controlled Trials (Cochrane Register of Studies Online), MEDLINE, and Embase on 22 May 2018. We checked clinical trials registers and reference lists of retrieved articles for additional studies.

SELECTION CRITERIA

We included randomized trials that compared a single postoperative dose of intravenous diclofenac with placebo or another active treatment, for treating acute postoperative pain in adults following any surgery.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently considered trials for review inclusion, assessed risk of bias, and extracted data.Our primary outcome was the number of participants in each arm achieving at least 50% pain relief over a four- and six-hour period.Our secondary outcomes were time to, and number of participants using rescue medication; withdrawals due to lack of efficacy, AEs, and for any cause; and number of participants experiencing any AE, serious AEs (SAEs), and NSAID-related AEs. We performed a post hoc analysis of opioid-related AEs, to enable indirect comparisons with other analyses of postoperative analgesics.For subgroup analysis, we planned to analyze different doses and formulations of parenteral diclofenac separately.We assessed the overall quality of the evidence for each outcome using GRADE and created two 'Summary of findings' tables.

MAIN RESULTS

We included eight studies, involving 1756 participants undergoing various surgeries (dental, mixed minor, abdominal, and orthopedic), with 20 to 175 participants receiving intravenous diclofenac in each study. Mean study population ages ranged from 24.5 years to 54.5 years. Intravenous diclofenac doses varied among and within studies, ranging from 3.75 mg to 75 mg. Five studies assessed newer formulations of parenteral diclofenac that could be administered as an undiluted intravenous bolus. Most studies had an unclear risk of bias for several domains and a high risk of bias due to small sample size. The overall quality of evidence for each outcome was generally low for reasons including unclear risk of bias in studies, imprecision, and low event numbers.Primary outcomeThree studies (277 participants) produced a number needed to treat for an additional beneficial outcome (NNTB) for at least 50% of maximum pain relief versus placebo of 2.4 (95% confidence interval (CI) 1.9 to 3.1) over four hours (low-quality evidence). Four studies (436 participants) produced an NNTB of 3.8 versus placebo (95% CI 2.9 to 5.9) over six hours (low-quality evidence). No studies provided data for the comparison of intravenous diclofenac with another NSAID over four hours. At six hours there was no difference between intravenous diclofenac and another NSAID (low-quality evidence).Secondary outcomesFor secondary efficacy outcomes, intravenous diclofenac was generally superior to placebo and similar to other NSAIDs.For time to rescue medication, comparison of intravenous diclofenac versus placebo demonstrated a median of 226 minutes for diclofenac versus 80 minutes for placebo (5 studies, 542 participants, low-quality evidence). There were insufficient data for pooled analysis for comparisons of diclofenac with another NSAID (very low-quality evidence).For the number of participants using rescue medication, two studies (235 participants) compared diclofenac with placebo. The number needed to treat to prevent one additional harmful event (NNTp) (here, the need for rescue medication) compared with placebo was 3.0 (2.2 to 4.5, low-quality evidence). The comparison of diclofenac with another NSAID included only one study (98 participants). The NNTp was 4.5 (2.5 to 33) for ketorolac versus diclofenac (very low-quality evidence).The numbers of participants withdrawing were generally low and inconsistently reported (very low-quality evidence). Participant withdrawals were: 6% (8/140) diclofenac versus 5% (7/128) placebo, and 9% (8/87) diclofenac versus 7% (6/82) another NSAID for lack of efficacy; 2% (4/211) diclofenac versus 0% (0/198) placebo, and 3% (4/138) diclofenac versus 2% (2/129) another NSAID due to AEs; and 11% (21/191) diclofenac versus 17% (30/179) placebo, and 18% (21/118) diclofenac versus 15% (17/111) another NSAID for any cause.Overall adverse event rates were similar between intravenous diclofenac and placebo (71% in both groups, 2 studies, 296 participants) and between intravenous diclofenac and another NSAID (55% and 58%, respectively, 2 studies, 265 participants) (low-quality evidence for both comparisons). Serious and specific AEs were rare, preventing meta-analysis.There were sufficient data for a dose-effect analysis for our primary outcome for only one alternative dose, 18.75 mg. Analysis of the highest dose employed in each study demonstrated a relative benefit compared with placebo of 1.9 (1.4 to 2.4), whereas for the group receiving 18.75 mg, the relative benefit versus placebo was 1.6 (1.2 to 2.1, 2 studies). Compared to another NSAID, the high-dose analysis demonstrated a relative benefit of 0.9 (0.8 to 1.1), for the group receiving 18.75 mg, the relative benefit was 0.78 (0.65 to 0.93). For direct comparison of high dose versus 18.75 mg, the proportion of participants with at least 50% pain relief was 66% (90/137) for the high-dose arm versus 57% (77/135) in the low-dose arm. There were insufficient data for subgroup meta-analysis of different diclofenac formulations.

AUTHORS' CONCLUSIONS

The amount and quality of evidence for the use of intravenous diclofenac as a treatment for postoperative pain is low. The available evidence indicates that postoperative intravenous diclofenac administration offers good pain relief for the majority of patients, but further research may impact this estimate. Adverse events appear to occur at a similar rate to other NSAIDs. Insufficient information is available to assess whether intravenous diclofenac has a different rate of bleeding, renal dysfunction, or cardiovascular events versus other NSAIDs. There was insufficient information to evaluate the efficacy and safety of newer versus traditional formulations of intravenous diclofenac. There was a lack of studies in major and cardiovascular surgeries and in elderly populations, which may be at increased risk for adverse events.

Safety of Injectable HPβCD-Diclofenac in Older Patients with Acute Moderate-to-Severe Postoperative Pain: A Pooled Analysis of Three Phase III Trials

BACKGROUND

Hydroxypropyl-β-cyclodextrin-diclofenac (HPβCD-diclofenac) is an NSAID used to treat acute moderate-to-severe postoperative pain. This post hoc analysis investigated the safety of HPβCD-diclofenac in patients aged ≥ 65 years.

METHODS

Data from three phase III trials of HPβCD-diclofenac in adult patients with acute moderate-to-severe postoperative pain were pooled (NCT00448110, NCT00507026, and NCT00726388). Patients who received one or more dose of HPβCD-diclofenac or placebo were included and stratified according to age: < 65, 65-74, or ≥ 75 years. Numerical and categorical variables were compared across the groups using ANOVA and Cochran-Mantel-Haenszel tests, respectively. Cochran-Mantel-Haenszel relative risks compared with placebo were calculated, adjusted by study.

RESULTS

Overall, 1289 patients were included: 878, 282, and 129 in the < 65, 65-74, and ≥ 75-years groups, respectively. Overall incidence of treatment-emergent adverse events (TEAEs) was similar in the three groups (p = 0.4360). Incidences of postoperative anemia (p < 0.0001), constipation (p = 0.0017), and hypotension (p = 0.0003) increased significantly across the age groups, whereas headache (p = 0.0008) and flatulence (p = 0.0118) decreased significantly. Relative risks for all System Organ Class categories and preferred terms investigated were similar among the groups and similar to placebo.

CONCLUSIONS

Overall incidence of TEAEs in patients aged 65-74 or ≥ 75 years was similar to patients aged < 65 years. The groups displayed similar relative risks for the most frequent TEAEs, which were all similar to placebo. The TEAE profiles of the groups showed differences, all of which may be anticipated due to age-related differences in susceptibility and the types of surgery most commonly performed in each group. CLINICALTRIALS.

GOV IDENTIFIERS

NCT00448110, NCT00507026, and NCT00726388.

Pharmacokinetics of Diclofenac and Hydroxypropyl-β-Cyclodextrin (HPβCD) Following Administration of Injectable HPβCD-Diclofenac in Subjects With Mild to Moderate Renal Insufficiency or Mild Hepatic Impairment

Given their established analgesic properties, nonsteroidal anti‐inflammatory drugs (NSAIDs) represent an important postoperative pain management option. This study investigated: (1) the effects of mild or moderate renal insufficiency and mild hepatic impairment on the pharmacokinetics (PK) of diclofenac and hydroxypropyl‐β‐cyclodextrin (HPβCD) following administration of the injectable NSAID HPβCD‐diclofenac; and (2) the PK of HPβCD following administration of HPβCD‐diclofenac and intravenous itraconazole formulated with HPβCD in healthy adults. Diclofenac clearance (CL) and volume of distribution (V_z) tended to increase with decreasing renal function (moderate insufficiency versus mild insufficiency or healthy controls). Regression analysis demonstrated a significant relationship between V_z (but not CL or elimination half‐life, t_½) and renal function. HPβCD CL was significantly decreased in subjects with renal insufficiency, with a corresponding increase in t_½. There were no significant differences in diclofenac or HPβCD PK in subjects with mild hepatic impairment versus healthy subjects. Exposure to HPβCD in healthy subjects following HPβCD‐diclofenac administration was ∼12% of that with intravenous itraconazole, after adjusting for dosing schedule and predicted accumulation (<5% without adjustment). With respect to PK properties, these results suggest that HPβCD‐diclofenac might be administered to patients with mild or moderate renal insufficiency or mild hepatic impairment without dose adjustment (NCT00805090).

Efficacy and Safety Profile of Diclofenac/Cyclodextrin and Progesterone/Cyclodextrin Formulations: A Review of the Literature Data

Background

According to health technology assessment, patients deserve the best medicine. The development of drugs associated with solubility enhancers, such as cyclodextrins, represents a measure taken in order to improve the management of patients. Different drugs, such as estradiol, testosterone, dexamethasone, opioids, non-steroidal anti-inflammatories (NSAIDs; i.e. diclofenac), and progesterone are associated with cyclodextrins. Products containing the association of diclofenac/cyclodextrins are available for subcutaneous, intramuscular, and intravenous administration in doses that range from 25 to 75 mg. Medicinal products containing the association of progesterone/cyclodextrins are indicated for intramuscular and subcutaneous injection at a dose equal to 25 mg.

Objectives and Methods

The effects of cyclodextrins have been discussed in the solubility profile and permeability through biological membranes of drug molecules. A literature search was performed in order to give an overview of the pharmacokinetic characteristics, and efficacy and safety profiles of diclofenac/hydroxypropyl-β-cyclodextrin (HPβCD) and progesterone/HPβCD associations.

Results

The results of more than 20 clinical studies were reviewed. It was suggested that the new diclofenac/HPβCD formulation gives a rapid and effective response to acute pain and, furthermore, has pharmacokinetic and efficacy/safety profiles comparable to other medicinal products not containing cyclodextrins. One of the principal aspects of these new diclofenac formulations is that in lowering the dose (lower than 50 mg) the drugs could be more tolerable, especially in patients with comorbid conditions. Moreover, results of studies investigating the characteristics of progesterone and cyclodextrins showed that the new formulation (progesterone/HPβCD 25 mg solution) has the same bioavailability as other products containing progesterone. It is more rapidly absorbed and allows the achievement of peak plasma concentrations in a shorter time. Finally, the new formulation of progesterone was shown to be safe and not inferior to other products already on the market, with the exception of progesterone administered vaginally.

Conclusions

As shown by the results of clinical studies presented in this review, the newly approved medicines containing cyclodextrins have been found to be as effective and as well-tolerated as other medicinal products that do not contain cyclodextrins. Moreover, the newly approved lower dose of diclofenac associated with cyclodextrins is consistent with the European Medicines Agency recommendations reported in the revision of the Assessment Report for Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) and Cardiovascular Risk. Finally, the use of cyclodextrins led to significant increases in solubility and bioavailability of drugs, such as diclofenac and progesterone, and improvement in the efficacy and safety of these drugs.

Diclofenac Sodium Bolus Injection (Dyloject(TM)): A Review in Acute Pain Management

An intravenous bolus formulation of the non-steroidal anti-inflammatory drug diclofenac sodium has been developed using hydroxypropyl-β-cyclodextrin (HPβCD) as a solubility enhancer. HPβCD diclofenac (Dyloject(TM)) is available for use in adults in the USA for the management of mild to moderate pain, and as monotherapy or in combination with opioid analgesics for the management of moderate to severe pain. In two multicentre, phase III studies in adults with acute moderate to severe postoperative pain, HPβCD diclofenac significantly reduced pain intensity and the need for rescue medication compared with placebo. In these studies, the tolerability profile of HPβCD diclofenac was generally similar to that of placebo and adverse events were mostly mild to moderate in severity. Constipation, infusion-site pain and dizziness were the most frequently reported adverse reactions occurring numerically more frequently with HPβCD diclofenac than placebo. Therapy with HPβCD diclofenac does not appear to be associated with an increased risk of cardiovascular, renal or bleeding-related adverse events versus placebo. Thus, HPβCD diclofenac extends the treatment options currently available for the management of moderate to severe postoperative pain in adults.

Postoperative opioid sparing with injectable hydroxypropyl-β-cyclodextrin-diclofenac: pooled analysis of data from two Phase III clinical trials

Purpose

Use of nonopioid analgesics (including nonsteroidal anti-inflammatory drugs) for postoperative pain management can reduce opioid consumption and potentially prevent opioid-related adverse events. This study examined the postoperative opioid-sparing effect of repeated-dose injectable diclofenac formulated with hydroxypropyl-β-cyclodextrin (HPβCD)-diclofenac.

Patients and methods

Pooled data from two double-blind, randomized, placebo- and active comparator-controlled Phase III trials were analyzed. Patients received HPβCD-diclofenac, placebo, or ketorolac by intravenous injection every 6 hours for up to 5 days following abdominal/pelvic or orthopedic surgery. Rescue opioid use was evaluated from the time of first study drug administration to up to 120 hours following the first dose in the overall study population and in subgroups defined by baseline pain severity, age, and HPβCD-diclofenac dose.

Results

Overall, 608 patients received ≥1 dose of study medication and were included in the analysis. While 93.2% of patients receiving placebo required opioids, the proportion of patients requiring opioids was significantly lower for patients receiving HPβCD-diclofenac (18.75, 37.5, or 50 mg) or ketorolac (P<0.005 for all comparisons). Mean cumulative opioid dose and number of doses were significantly lower among patients receiving HPβCD-diclofenac versus placebo for the 0–24 through 0–120 hour time periods (P<0.0001), as well as versus ketorolac for the 0–72 through 0–120 hour time periods (P<0.05). HPβCD-diclofenac significantly reduced opioid consumption versus placebo in subgroups based on baseline pain severity (moderate, severe) and age (<65 years, ≥65 years) from the 0–24 hour period onward. When compared to ketorolac, HPβCD-diclofenac also significantly reduced cumulative opioid consumption among patients with moderate baseline pain (0–72 through 0–120 hours) and opioid dose number among patients ≥65 years old (0–24 through 0–120 hours).

Conclusion

HPβCD-diclofenac can reduce postoperative opioid requirements. As this analysis was not powered to compare opioid-related adverse event rates, follow-up studies examining the clinical impact of HPβCD-diclofenac’s opioid sparing are warranted.

A Pooled Analysis Evaluating Renal Safety in Placebo- and Active Comparator-Controlled Phase III Trials of Multiple-Dose Injectable HPβCD-Diclofenac in Subjects with Acute Postoperative Pain

OBJECTIVE : While injectable nonsteroidal anti-inflammatory drugs (NSAIDs) are a key component of postoperative multimodal analgesia, renal safety concerns may limit use in some patients. This study examined the renal safety of injectable HPβCD-diclofenac when given for ≤ 5 days following orthopedic or abdominal/pelvic surgery. METHODS : Pooled analysis of data from two randomized, placebo- and active comparator-controlled phase III trials in 608 total patients was conducted. Renal safety was assessed by examining treatment-emergent adverse events (AEs) and postoperative blood urea nitrogen (BUN) and serum creatinine shifts. RESULTS : There were three renal AEs each in the HPβCD-diclofenac (n = 318 patients) and placebo (n = 148 patients) groups, and two renal AEs in the ketorolac group (n = 142 patients). No significant difference in renal AE risk was detected for patients receiving HPβCD-diclofenac (RR: 1.40 [0.15,13.3]; P = 0.75) or ketorolac (RR: 2.08 [0.19,22.7]; P = 0.56) versus placebo. All renal AEs were mild or moderate in severity, and a single renal AE (acute renal failure in a patient receiving HPβCD-diclofenac) was treatment-related. One incidence of postoperative shift to high (> upper limit of normal) serum creatinine occurred in the HPβCD-diclofenac group (n = 2 in the ketorolac group). Mean changes in serum creatinine or BUN did not differ significantly between patients receiving HPβCD-diclofenac and placebo. CONCLUSIONS : While this analysis examined relatively brief exposure typical for parenterally administered analgesics in the postoperative setting in patients with largely normal renal function, the results suggest that HPβCD-diclofenac use for acute postoperative pain may not be associated with added renal safety risks over placebo in this patient population.

Cardiovascular safety of hydroxypropyl-β-cyclodextrin-diclofenac in the management of acute postsurgical pain: a pooled analysis of 2 randomized, double-blind, placebo- and active comparator-controlled phase III clinical trials

STUDY OBJECTIVE

Long-term use of nonsteroidal anti-inflammatory drugs, including selective and nonselective cyclooxygenase inhibitors, has been suggested to be associated with cardiovascular (CV) safety risks. Data are limited regarding CV risks associated with short-term nonsteroidal anti-inflammatory drug use, including injectable formulations, although it has been suggested that even a single dose may increase CV adverse event (AE) risk. The objective of this study was to examine the CV safety of an injectable diclofenac formulation solubilized with hydroxypropyl-β-cyclodextrin (HPβCD) when given for ≤5days postoperatively.

DESIGN

A pooled analysis of CV AEs from 2 pivotal phase III clinical trials examining the efficacy and safety of intravenous (IV) HPβCD-diclofenac vs placebo and the active comparator ketorolac was conducted.

SETTING

Postoperative, with treatment initiated in the postanesthesia care unit ≤6hours postsurgery.

PATIENTS

Overall, 608 abdominal/pelvic and orthopedic surgery patients met inclusion criteria and received ≥1 study medication dose.

INTERVENTIONS

Patients received either HPβCD-diclofenac, ketorolac, or placebo via IV bolus injection every 6hours, for ≤5days postsurgery.

MEASUREMENTS

CV AEs, reported by study investigators, were evaluated through the treatment period and follow-up (≤37days after last study medication dose), and relative CV AE risks were estimated.

MAIN RESULTS

IV HPβCD-diclofenac was not associated with increased treatment-emergent CV AE incidence vs placebo (11.6% vs 12.2%; relative risk, 0.96 [95% confidence interval, 0.56-1.62]). Serious CV AEs as well as treatment-related AEs were uncommon, and there were no reports of myocardial infarction or cerebrovascular accident. CV AEs were uncommon during the follow-up period, occurring in 1.3%, 0%, and 1.4% of patients in the HPβCD-diclofenac, ketorolac, and placebo groups, respectively.

CONCLUSIONS

Although a longer duration follow-up study in a larger patient population would expand our understanding of potential CV risks, the present analysis suggests that postoperative use of HPβCD-diclofenac does not present an added CV safety risk over placebo.

Advances in NSAID development: evolution of diclofenac products using pharmaceutical technology

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylacetic acid class with anti-inflammatory, analgesic, and antipyretic properties. Contrary to the action of many traditional NSAIDs, diclofenac inhibits cyclooxygenase (COX)-2 enzyme with greater potency than it does COX-1. Similar to other NSAIDs, diclofenac is associated with serious dose-dependent gastrointestinal, cardiovascular, and renal adverse effects. Since its introduction in 1973, a number of different diclofenac-containing drug products have been developed with the goal of improving efficacy, tolerability, and patient convenience. Delayed- and extended-release forms of diclofenac sodium were initially developed with the goal of improving the safety profile of diclofenac and providing convenient, once-daily dosing for the treatment of patients with chronic pain. New drug products consisting of diclofenac potassium salt were associated with faster absorption and rapid onset of pain relief. These include diclofenac potassium immediate-release tablets, diclofenac potassium liquid-filled soft gel capsules, and diclofenac potassium powder for oral solution. The advent of topical formulations of diclofenac enabled local treatment of pain and inflammation while minimizing systemic absorption of diclofenac. SoluMatrix diclofenac, consisting of submicron particles of diclofenac free acid and a proprietary combination of excipients, was developed to provide analgesic efficacy at reduced doses associated with lower systemic absorption. This review illustrates how pharmaceutical technology has been used to modify the pharmacokinetic properties of diclofenac, leading to the creation of novel drug products with improved clinical utility.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

P-glycoprotein modulates morphine uptake into the CNS: a role for the non-steroidal anti-inflammatory drug diclofenac

Our laboratory has previously demonstrated that peripheral inflammatory pain (PIP), induced by subcutaneous plantar injection of λ-carrageenan, results in increased expression and activity of the ATP-dependent efflux transporter P-glycoprotein (P-gp) that is endogenously expressed at the blood-brain barrier (BBB). The result of increased P-gp functional expression was a significant reduction in CNS uptake of morphine and, subsequently, reduced morphine analgesic efficacy. A major concern in the treatment of acute pain/inflammation is the potential for drug-drug interactions resulting from P-gp induction by therapeutic agents co-administered with opioids. Such effects on P-gp activity can profoundly modulate CNS distribution of opioid analgesics and alter analgesic efficacy. In this study, we examined the ability of diclofenac, a non-steroidal anti-inflammatory drug (NSAID) that is commonly administered in conjunction with the opioids during pain therapy, to alter BBB transport of morphine via P-gp and whether such changes in P-gp morphine transport could alter morphine analgesic efficacy. Administration of diclofenac reduced paw edema and thermal hyperalgesia in rats subjected to PIP, which is consistent with the known mechanism of action of this NSAID. Western blot analysis demonstrated an increase in P-gp expression in rat brain microvessels not only following PIP induction but also after diclofenac treatment alone. Additionally, in situ brain perfusion studies showed that both PIP and diclofenac treatment alone increased P-gp efflux activity resulting in decreased morphine brain uptake. Critically, morphine analgesia was significantly reduced in animals pretreated with diclofenac (3 h), as compared to animals administered diclofenac and morphine concurrently. These novel findings suggest that administration of diclofenac and P-gp substrate opioids during pain pharmacotherapy may result in a clinically significant drug-drug interaction.

Single-dose and multiple-dose pharmacokinetics and dose proportionality of intravenous and intramuscular HPβCD-diclofenac (Dyloject) compared with other diclofenac formulations

STUDY OBJECTIVE

To evaluate single- and repeated-dose pharmacokinetics (PK) and dose proportionality of hydroxypropyl-β-cyclodextrin (HPβCD)-diclofenac compared with Voltarol after intravenous (IV) and intramuscular (IM) administration.

DESIGN

Study 1: Single-dose randomized four-way crossover study. Study 2: Multiple-dose randomized three-way crossover study.

SETTING

Clinical research center.

SUBJECTS

Healthy adult volunteers.

INTERVENTION

Study 1: Subjects received HPβCD-diclofenac and Voltarol, IV and IM, with a 5-day washout between treatment periods. Study 2: Subjects received two doses of IV HPβCD-diclofenac and oral Cataflam once every 6 hours for four doses with a 48-hour washout period between treatment periods.

MEASUREMENTS AND MAIN RESULTS

Study 1: IV HPβCD-diclofenac had a higher peak plasma concentration (Cmax ) and earlier time to reach maximum plasma concentration (Tmax ), but equivalent plasma exposure (area under the curve from time zero to t [AUC0-t ]) to IV Voltarol. The geometric mean ratio of HPβCD-diclofenac (IV) to Voltarol (IV) for AUC0-t was 106.27%. The geometric mean ratio of HPβCD-diclofenac (IM) to Voltarol (IM) for AUC0-t was 110.91%. The geometric mean ratio of HPβCD-diclofenac (IV) to HPβCD-diclofenac (IM) for AUC0-t was 101.25%. The geometric mean ratio of HPβCD-diclofenac (IM) to Voltarol (IV) for AUC0-t was 104.96%. Study 2: Cmax for diclofenac was 2904 and 6031 ng/ml after the first IV dose of 18.75 and 37.5 mg HPβCD-diclofenac, respectively, and was 3090 and 5617 ng/ml after the fourth dose, indicating no accumulation. Plasma exposures to 18.75 mg (866 ng·hour/ml) and 37.5 mg (1843 ng·hour/ml) IV HPβCD-diclofenac bracketed that of oral Cataflam 50 mg (1473 ng·hour/ml).

CONCLUSIONS

Study 1: Bioavailability in terms of AUC after IV administration was equivalent for HPβCD-diclofenac compared with Voltarol and after IM administration of HPβCD-diclofenac and Voltarol. Bioavailability in terms of AUC after IM administration of HPβCD-diclofenac was equivalent to IV administration of HPβCD-diclofenac and IV administration of Voltarol. Study 2: HPβCD-diclofenac showed dose proportionality after single- and multiple-dose administration and no accumulation of HPβCD-diclofenac. HPβCD-diclofenac was safe and well tolerated following IV and IM administration.

Safety of a novel parenteral formulation of diclofenac after major orthopedic or abdominal/pelvic surgery in a population including anticoagulated, elderly or renally insufficient patients: an open-label, multiday, repeated dose clinical trial

OBJECTIVE

Decisions to use or avoid nonsteroidal anti-inflammatory drugs (NSAIDs) for postsurgical pain are often influenced by concerns about bleeding and renal adverse effects. The objective of this study was to evaluate the safety of a novel parenteral NSAID, hydroxypropyl-β-cyclodextrin (HPβCD) diclofenac, in a large postsurgical patient population, with particular focus on bleeding and renal effects.

METHODS

This was a large open-label study in adult patients with acute moderate-to-severe pain following major surgery. Patients received ≥2 days of continuous treatment with HPβCD diclofenac, administered as a small-volume bolus injection every 6 hours. Few exclusion criteria were applied in order to reflect surgical patient populations commonly managed in clinical practice. Adverse events (AEs) were recorded throughout the study. The incidences of bleeding- and renal-related AEs were examined in patient subpopulations with known risk factors for NSAID-induced complications: advanced age, pre-existing renal insufficiency, concomitant anticoagulant use, prolonged exposure, elevated dosage, and major surgeries.

RESULTS

Of the total 971 patients studied, 38% were ≥65 years old (12% >75 years), 62% received concomitant anticoagulants, and 6% had pre-existing renal insufficiency. HPβCD diclofenac was well tolerated by the patient population. AE rates are presented by risk factor to enable clinicians to better describe renal- or bleeding-related AEs.

CONCLUSIONS

In addition to its previously demonstrated efficacy, this study provides evidence of HPβCD diclofenac's safety in a large postsurgical population including anticoagulated, elderly or renally insufficient patients. Because study exclusion criteria were minimal, these findings may be broadly generalizable to populations commonly treated in clinical practice.

Effects of injectable HPβCD-diclofenac on the human delayed rectifier potassium channel current in vitro and on proarrhythmic QTc in vivo

BACKGROUND

Novel formulations and administration routes of established drugs may result in higher maximum concentrations or total exposures and potentially cause previously unrecognized adverse events.

OBJECTIVE

This study evaluated the proarrhythmic potential of hydroxypropyl-β-cyclodextrin (HPβCD)-diclofenac, a novel injectable diclofenac formulation solubilized with hydroxypropyl-β-cyclodextrin (HPβCD), on ventricular electrical conduction in preclinical and clinical models.

METHODS

We assessed the effects of diclofenac, HPβCD, and HPβCD-diclofenac on the human delayed rectifier potassium channel (IKr) using human embryonic kidney (HEK) 293 cells transfected with a human ether-à-go-go-related gene (hERG) using whole-cell patch-clamp. In a single-dose, active- and placebo-controlled, 4-period crossover, thorough QT in vivo study, 70 healthy volunteers (mean age, 23.3 years; range, 18-49 years; 55.75% male) received HPβCD-diclofenac at 37.5- and 75-mg doses, inactive vehicle (placebo), and an active control (moxifloxacin).

RESULTS

In vitro, diclofenac produced no statistically significant effect on IKr. Significant, non-dose-dependent effects were observed in the presence of HPβCD or HPβCD-diclofenac of similar magnitude across the 300-fold dose range of concentrations tested, suggesting an artifact due to the detergent effect of HPβCD in this in vitro model. In vivo, neither HPβCD-diclofenac dose resulted in QTc prolongation ≥2 ms (≥5 ms is the threshold of clinical concern). No correlation was evident between changes in QTc and plasma concentrations of diclofenac or HPβCD. Confirming study sensitivity, moxifloxacin produced a mean QTc prolongation >10 ms.

CONCLUSIONS

The findings from the present study suggest that HPβCD-diclofenac does not have a dose-dependent effect in the in vitro hERG assay system and does not produce proarrhythmic QTc prolongation in vivo. ClinicalTrials.gov identifier: NCT01812538.