Pharmacokinetics and metabolism of the anti-inflammatory agent Voltaren

Engineering Innervated Musculoskeletal Tissues for Regenerative Orthopedics and Disease Modeling

Musculoskeletal (MSK) disorders significantly burden patients and society, resulting in high healthcare costs and productivity loss. These disorders are the leading cause of physical disability, and their prevalence is expected to increase as sedentary lifestyles become common and the global population of the elderly increases. Proper innervation is critical to maintaining MSK function, and nerve damage or dysfunction underlies various MSK disorders, underscoring the potential of restoring nerve function in MSK disorder treatment. However, most MSK tissue engineering strategies have overlooked the significance of innervation. This review first expounds upon innervation in the MSK system and its importance in maintaining MSK homeostasis and functions. This will be followed by strategies for engineering MSK tissues that induce post-implantation in situ innervation or are pre-innervated. Subsequently, research progress in modeling MSK disorders using innervated MSK organoids and organs-on-chips (OoCs) is analyzed. Finally, the future development of engineering innervated MSK tissues to treat MSK disorders and recapitulate disease mechanisms is discussed. This review provides valuable insights into the underlying principles, engineering methods, and applications of innervated MSK tissues, paving the way for the development of targeted, efficacious therapies for various MSK conditions.

Diclofenac, a NSAID, delays fracture healing in aged mice

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, belong to the most prescribed analgesic medication after traumatic injuries. However, there is accumulating evidence that NSAIDs impair fracture healing. Because bone regeneration in aged patients is subject to significant changes in cell differentiation and proliferation as well as a markedly altered pharmacological action of drugs, we herein analyzed the effects of diclofenac on bone healing in aged mice using a stable closed femoral facture model. Thirty-three mice (male n = 14, female n = 19) received a daily intraperitoneal injection of diclofenac (5 mg/kg body weight). Vehicle-treated mice (n = 29; male n = 13, female n = 16) served as controls. Fractured mice femora were analyzed by means of X-ray, biomechanics, micro computed tomography (μCT), histology and Western blotting. Biomechanical analyses revealed a significantly reduced bending stiffness in diclofenac-treated animals at 5 weeks after fracture when compared to vehicle-treated controls. Moreover, the callus tissue in diclofenac-treated aged animals exhibited a significantly reduced amount of bone tissue and higher amounts of fibrous tissue. Further histological analyses demonstrated less lamellar bone after diclofenac treatment, indicating a delay in callus remodeling. This was associated with a decreased number of osteoclasts and an increased expression of osteoprotegerin (OPG) during the early phase of fracture healing. These findings indicate that diclofenac delays fracture healing in aged mice by affecting osteogenic growth factor expression and bone formation as well as osteoclast activity and callus remodeling.

Safe and appropriate use of diclofenac in chronic kidney disease: An Indian perspective

Pain is most common symptom associated with progressive disorder, chronic kidney disease (CKD), and is usually undertreated during the early stages of CKD. So, present review was conducted to evaluate the challenges for the management of pain in CKD patients and addresses the scope for considering Diclofenac as suitable alternative for pain management in CKD patient. The database PubMed and Google Scholar were searched from 1970 to Dec 2020 for literature published in English and all studies, review articles that examined the use of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) in pain management in CKD patients were included. Literatures revealed that there is a considerable challenge in appropriate management of pain in CKD patients include understanding the altered pharmacokinetics and pharmacodynamics of analgesics in CKD patients and the risk of acute interstitial nephritis. The shorter duration of analgesics is acceptable and considered to pose a low risk of acute interstitial nephritis in patients. Considering that Diclofenac has a shorter half-life and high efficacy, it may be well tolerated in patients with CKD. The acceptance of Diclofenac is partly attributed to being a potent COX-2 inhibitor with the lowest IC50 and its rapid onset of action at lowest effective dose. In conclusion, diclofenac may be well tolerated in patients of renal impairment when used at lowest effective dose for shortest dose duration. Diclofenac is worthy of consideration in mild to moderate cases of CKD. For effective pain management, it is vital to evaluate the tolerability and efficacy of the available analgesics critically.

Drug-drug interaction between diclofenac and gamma-hydroxybutyric acid

Gamma hydroxybutyric acid (GHB) has been approved clinically to treat excessive daytime sleepiness and cataplexy in patients with narcolepsy, alcohol and opioid withdrawal, and as an anesthetic. The use of GHB clinically is limited due to its high abuse potential. The absorption, clearance and tissue uptake of GHB is mediated by proton-dependent and sodium-coupled monocarboxylate transporters (MCTs and SMCTs) and inhibition of these transporters may result in a change in GHB pharmacokinetics and pharmacodynamics. Previous studies have reported that non-steroidal anti-inflammatory drugs (NSAIDs) may inhibit these monocarboxylate transporters. Therefore, the purpose of this work was to analyze the interaction between GHB (at a dose of 600 mg/kg i. v.) and the NSAID, diclofenac, by examining the effects of this drug on the in vivo pharmacokinetics and pharmacodynamics in rat studies. The pharmacodynamic effect evaluated was respiratory depression, a measure of toxicity observed by GHB at this dose. There was an improvement in the respiratory rate with diclofenac administration suggesting an effect of diclofenac on GHB toxicity. In vitro studies with rat blood brain endothelial cells (RBE4) that express MCT1 indicated that diclofenac can inhibit GHB transport with an IC₅₀ of 10.6 μM at pH 7.4. In vivo studies found a decrease in brain GHB concentrations and a decrease in the brain-to-plasma concentration ratio following diclofenac treatment. With this study we can conclude that diclofenac and potentially other NSAIDs can inhibit the transport of GHB into the brain, therefore decreasing GHB's pharmacodynamic effects and toxicity.

Drug-drug-gene interactions as mediators of adverse drug reactions to diclofenac and statins: a case report and literature review

Concomitant treatment with drugs that inhibit drug metabolising enzymes and/or transporters, such as commonly prescribed statins and nonsteroidal anti-inflammatory drugs (NSAIDs), has been associated with prolonged drug exposure and increased risk of adverse drug reactions (ADRs) due to drug-drug interactions. The risk is further increased in patients with chronic diseases/comorbidities who are more susceptible because of their genetic setup or external factors. In that light, we present a case of a 46-year-old woman who had been experiencing acute renal and hepatic injury and myalgia over two years of concomitant treatment with diclofenac, atorvastatin, simvastatin/fenofibrate, and several other drugs, including pantoprazole and furosemide. Our pharmacogenomic findings supported the suspicion that ADRs, most notably the multi-organ toxicity experienced by our patient, may be owed to drug-drug-gene interactions and increased bioavailability of the prescribed drugs due to slower detoxification capacity and decreased hepatic and renal elimination. We also discuss the importance of CYP polymorphisms in the biotransformation of endogenous substrates such as arachidonic acid and their modulating role in pathophysiological processes. Yet even though the risks of ADRs related to the above mentioned drugs are substantially evidenced in literature, pre-emptive pharmacogenetic analysis has not yet found its way into common clinical practice.

Using Prescription and Wastewater Data to Estimate the Correction Factors of Atenolol, Carbamazepine, and Naproxen for Wastewater-Based Epidemiology Applications

The correction factor (CF) is a critical parameter in wastewater-based epidemiology (WBE) that significantly influences the accuracy of the final consumption estimates. However, most CFs have been derived from a few old pharmacokinetic studies and should be re-evaluated and refined to improve the accuracy of the WBE approach. This study aimed to review and estimate the CFs for atenolol, carbamazepine, and naproxen for WBE using the daily mass loads of those pharmaceuticals in wastewater and their corresponding dispensed prescription data in Australia. Influent wastewater samples were collected from wastewater treatment plants serving approximately 24% of the Australian population and annual national dispensed prescription data. The estimated CFs for atenolol and carbamazepine are 1.37 (95% CI: 1.17-1.66) and 8.69 (95% CI: 7.66-10.03), respectively. Due to significant over-the-counter sales of naproxen, a reliable CF could not be estimated based on prescription statistics. Using an independent dataset of 186 and 149 wastewater samples collected in an urban catchment in 2011 and 2012, WBE results calculated using the new CFs matched well with the dispensed data for atenolol and carbamazepine in the catchment area.

Development of a Biphasic-Release Multiple-Unit Pellet System with Diclofenac Sodium Using Novel Calcium Phosphate-Based Starter Pellets

Novel calcium phosphate-based starter pellets were used to develop a biphasic-release multiple-unit pellet system (MUPS) with diclofenac sodium as a model drug in the form of hard gelatin capsules. For comparative purposes, corresponding formulations based on the inert cores made of microcrystalline cellulose, sucrose and isomalt were prepared. The developed system consisted of two types of drug-layered pellets attaining different release patterns: delayed-release (enteric-coated) and extended-release. Dissolution characteristics were examined using both compendial and biorelevant methods, which reflected fed and fasting conditions. The results were collated with an equivalent commercial product but prepared with the direct pelletization technique.

Comprehensive review of genotoxicity data for diclofenac

Diclofenac is a non-steroidal anti-inflammatory drug discovered several decades ago, which has since been used by an estimated one billion patients and has demonstrated an acceptable safety profile. In support of its marketing approval, a comprehensive set of genotoxicity studies were conducted in vitro and in vivo. Despite the fact that these studies preceded both Good Laboratory Practice (GLP) requirements and International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines on genotoxicity testing, they were conducted using the best scientific principles and are considered appropriate by contemporary standards. In addition to bacterial mutagenicity and mammalian in vitro assays, repeat-dose somatic, germ cell and dominant lethal assays were conducted. These data are made available for the first time to offer researchers an opportunity to review the existing data set that unequivocally demonstrates that diclofenac sodium is not genotoxic. This is further substantiated by long-term bioassay data demonstrating that diclofenac sodium has no carcinogenic potential in rodents. However, more recently, new studies have been published showing a genotoxic potential for diclofenac in novel or modified in vitro test systems. These new publications are discussed in the context of the existing comprehensive data package.

Prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis with rectal non-steroidal anti-inflammatory drugs

Acute pancreatitis is the most common and feared adverse event associated with performance of endoscopic retrograde cholangiopancreatography (ERCP). Unremitting effort has been made for over 40 years to minimize the frequency and severity of this complication. Recently, the use of rectal non-steroidal anti-inflammatory drugs (NSAIDs) have opened a new era for its prevention. This review focuses on the role of NSAIDs in pancreatitis, the pharmacokinetics of these agents, and summarizes the results of clinical trials with rectal NSAIDs alone and combination regimens in the prevention of post-ERCP pancreatitis.

Identification and Characterization of Efflux Transporters That Modulate the Subtoxic Disposition of Diclofenac and Its Metabolites

In the present work, in vivo transporter knockout (KO) mouse models were used to characterize the disposition of diclofenac (DCF) and its primary metabolites following a single subtoxic dose in mice lacking breast cancer resistance protein (Bcrp) or multidrug resistance-associated protein (Mrp)3. The results indicate that Bcrp acts as a canalicular efflux mediator for DCF, as wild-type (WT) mice had biliary excretion values that were 2.2- to 2.6-fold greater than Bcrp KO mice, although DCF plasma levels were not affected. The loss of Bcrp resulted in a 1.8- to 3.2-fold increase of diclofenac acyl glucuronide (DCF-AG) plasma concentrations in KO animals compared with WT mice, while the biliary excretion of DCF-AG increased 1.4-fold in WT versus KO mice. Furthermore, Mrp3 was found to mediate the basolateral transport of DCF-AG, but not DCF or 4'-hydroxy diclofenac. WT mice had DCF-AG plasma concentrations 7.0- to 8.6-fold higher than Mrp3 KO animals; however, there were no changes in biliary excretion of DCF-AG. Vesicular transport experiments with human MRP3 demonstrated that MRP3 is able to transport DCF-AG via low- and high-affinity binding sites. The low-affinity MRP3 transport had a V _max and K _m of 170 pmol/min/mg and 98.2 µM, respectively, while the high-affinity V _max and K _m parameters were estimated to be 71.9 pmol/min/mg and 1.78 µM, respectively. In summary, we offer evidence that the disposition of DCF-AG can be affected by both Bcrp and Mrp3, and these findings may be applicable to humans.

Application of data mining approach to identify drug subclasses based on solubility and permeability

Solubility and permeability are recognized as key parameters governing drug intestinal absorption and represent the basis for biopharmaceutics drug classification. The Biopharmaceutics Classification System (BCS) is widely accepted and adopted by regulatory agencies. However, currently established low/high permeability and solubility boundaries are the subject of the ongoing scientific discussion. The aim of the present study was to apply data mining analysis on the selected drugs data set in order to develop a human permeability predictive model based on selected molecular descriptors, and to perform data clustering and classification to identify drug subclasses with respect to dose/solubility ratio (D/S) and effective permeability (P_eff ). The P_eff values predicted for 30 model drugs for which experimental human permeability data are not available were in good agreement with the reported fraction of drug absorbed. The results of clustering and classification analysis indicate the predominant influence of P_eff over D/S. Two P_eff cut-off values (1 × 10^-4 and 2.7 × 10^-4  cm/s) have been identified indicating the existence of an intermediate group of drugs with moderate permeability. Advanced computational analysis employed in the present study enabled the recognition of complex relationships and patterns within physicochemical and biopharmaceutical properties associated with drug bioperformance.

Mitochondrial dysfunction as a mechanism of drug-induced hepatotoxicity: current understanding and future perspectives

Mitochondria are critical cellular organelles for energy generation and are now also recognized as playing important roles in cellular signaling. Their central role in energy metabolism, as well as their high abundance in hepatocytes, make them important targets for drug-induced hepatotoxicity. This review summarizes the current mechanistic understanding of the role of mitochondria in drug-induced hepatotoxicity caused by acetaminophen, diclofenac, anti-tuberculosis drugs such as rifampin and isoniazid, anti-epileptic drugs such as valproic acid and constituents of herbal supplements such as pyrrolizidine alkaloids. The utilization of circulating mitochondrial-specific biomarkers in understanding mechanisms of toxicity in humans will also be examined. In summary, it is well-established that mitochondria are central to acetaminophen-induced cell death. However, the most promising areas for clinically useful therapeutic interventions after acetaminophen toxicity may involve the promotion of adaptive responses and repair processes including mitophagy and mitochondrial biogenesis, In contrast, the limited understanding of the role of mitochondria in various aspects of hepatotoxicity by most other drugs and herbs requires more detailed mechanistic investigations in both animals and humans. Development of clinically relevant animal models and more translational studies using mechanistic biomarkers are critical for progress in this area.

Relevance for patients:This review focuses on the role of mitochondrial dysfunction in liver injury mechanisms of clinically important drugs like acetaminophen, diclofenac, rifampicin, isoniazid, amiodarone and others. A better understanding ofthe mechanisms in animal models and their translation to patients will be critical for the identification of new therapeutic targets.

The pharmacokinetics and metabolism of diclofenac in chimeric humanized and murinized FRG mice

The pharmacokinetics of diclofenac were investigated following single oral doses of 10 mg/kg to chimeric liver humanized and murinized FRG and C57BL/6 mice. In addition, the metabolism and excretion were investigated in chimeric liver humanized and murinized FRG mice. Diclofenac reached maximum blood concentrations of 2.43 ± 0.9 µg/mL (n = 3) at 0.25 h post-dose with an AUC_inf of 3.67 µg h/mL and an effective half-life of 0.86 h (n = 2). In the murinized animals, maximum blood concentrations were determined as 3.86 ± 2.31 µg/mL at 0.25 h post-dose with an AUC_inf of 4.94 ± 2.93 µg h/mL and a half-life of 0.52 ± 0.03 h (n = 3). In C57BL/6J mice, mean peak blood concentrations of 2.31 ± 0.53 µg/mL were seen 0.25 h post-dose with a mean AUC_inf of 2.10 ± 0.49 µg h/mL and a half-life of 0.51 ± 0.49 h (n = 3). Analysis of blood indicated only trace quantities of drug-related material in chimeric humanized and murinized FRG mice. Metabolic profiling of urine, bile and faecal extracts revealed a complex pattern of metabolites for both humanized and murinized animals with, in addition to unchanged parent drug, a variety of hydroxylated and conjugated metabolites detected. The profiles in humanized mice were different to those of both murinized and wild-type animals, e.g., a higher proportion of the dose was detected in the form of acyl glucuronide metabolites and much reduced amounts as taurine conjugates. Comparison of the metabolic profiles obtained from the present study with previously published data from C57BL/6J mice and humans revealed a greater, though not complete, match between chimeric humanized mice and humans, such that the liver humanized FRG model may represent a model for assessing the biotransformation of such compounds in humans.

Inhibition of Methotrexate Uptake via Organic Anion Transporters OAT1 and OAT3 by Glucuronides of Nonsteroidal Anti-inflammatory Drugs

Combination therapy of non-steroidal anti-inflammatory drugs (NSAIDs) and methotrexate (MTX) sometimes triggers adverse effects, such as liver injury, renal failure, gastrointestinal disorders, and myelosuppression, owing to the reduction of MTX clearance. Previous reports have suggested that NSAIDs inhibit renal MTX uptake via organic anion transporters (OATs) and reduced folate transporter (RFC)-1 and efflux via multidrug resistance-associated proteins (MRPs). Recently, our laboratory found inhibitory effects of NSAIDs-glucuronide (NSAIDs-Glu), a major metabolite of NSAIDs, on MRP-mediated MTX transport as a new site of interaction between MTX and NSAIDs. However, it remains unclear that whether NSAIDs-Glu inhibit renal uptake of MTX. Therefore, the present study aimed to evaluate inhibitory effects of several NSAIDs-Glu (diclofenac, R- and S-ibuprofen, R- and S-flurbiprofen, and R- and S-naproxen) on human OAT1 and OAT3-mediated MTX transport. In this study, [³H]MTX uptake was observed by using human OAT1 and OAT3-overexpressing HEK293 cells in the presence or absence of NSAIDs-Glu. All examined NSAIDs-Glu exhibited concentration-dependent inhibitory effects on MTX uptake via OAT1 and OAT3. Our results indicated that NSAIDs-Glu are more potent (5- to 15-fold) inhibitors of OAT3 than OAT1. Moreover, stereoselective inhibitory effects of NSAIDs-Glu on OATs-mediated MTX uptake were not observed, unlike on MRPs-mediated transport. These findings suggest that inhibition of OAT1 and OAT3-mediated renal uptake of MTX by plasma NSAIDs-Glu may be one of the competitive sites underlying complex drug interaction between MTX and NSAIDs.

Prediction of Transporter-Mediated Drug-Drug Interactions for Baricitinib

Baricitinib, an oral selective Janus kinase 1 and 2 inhibitor, undergoes active renal tubular secretion. Baricitinib was not predicted to inhibit hepatic and renal uptake and efflux drug transporters, based on the ratio of the unbound maximum eliminating-organ inlet concentration and the in vitro half-maximal inhibitory concentrations (IC₅₀ ). In vitro, baricitinib was a substrate for organic anion transporter (OAT)3, multidrug and toxin extrusion protein (MATE)2-K, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP). Probenecid, a strong OAT3 inhibitor, increased the area under the concentration-time curve from time zero to infinity (AUC_[0-∞] ) of baricitinib by twofold and decreased renal clearance to 69% of control in healthy subjects. Physiologically based pharmacokinetic (PBPK) modeling reproduced the renal clearance of baricitinib and the inhibitory effect of probenecid using the in vitro IC₅₀ value of 4.4 μM. Using ibuprofen and diclofenac in vitro IC₅₀ values of 4.4 and 3.8 μM toward OAT3, 1.2 and 1.0 AUC_(0-∞) ratios of baricitinib were predicted. These predictions suggest clinically relevant drug-drug interactions (DDIs) with ibuprofen and diclofenac are unlikely.

Metabolic profiling identification of metabolites formed in Mediterranean mussels (Mytilus galloprovincialis) after diclofenac exposure

Despite the growing concern on the presence of pharmaceutically active compounds in the environment, few studies have been conducted on their metabolism in marine organisms. In this study, a non-targeted strategy based on the generation of chemical profiles generated by liquid chromatography combined with high resolution mass spectrometry was used to highlight metabolite production by the Mediterranean mussel (Mytilus galloprovincialis) after diclofenac exposure. This method allowed revealing the production of 13 metabolites in mussel tissues. Three of them were phase I metabolites, including 4'-hydroxy-diclofenac and 5-hydroxy-diclofenac. The remaining 10 were phase II metabolites, including sulfate and amino acids conjugates. Among all of the metabolites highlighted, 5 were reported for the first time in an aquatic organism exposed to diclofenac.

Involvement of Reactive Metabolites of Diclofenac in Cytotoxicity in Sandwich-Cultured Rat Hepatocytes

Background and Objectives:

Diclofenac (DIC) is metabolized to reactive metabolites such as diclofenac acyl-β-d-glucuronide (DIC-AG). It is possible that such reactive metabolites could cause tissue damage by formation of covalent protein adducts and other modification of cellular proteins or by induction of immune responses against its covalent protein adducts. However, the detailed mechanisms of idiosyncratic drug-induced liver injury (DILI) have been unclear. The objective is to clarify the involvement of DIC-AG and 4′hydroxydiclofenac (4′OH-DIC) in acute DILI.

Methods:

We examined the effects of inhibiting DIC-AG and 4′OH-DIC production on covalent protein adduct formation and lactate dehydrogenase leakage using sandwich-cultured rat hepatocytes (SCRHs).

Results:

After pretreatment of SCRH with (−)-borneol (BOR, a uridine diphosphate (UDP)-glucuronosyltransferase inhibitor) or sulfaphenazole (SUL, a cytochrome P450 2C9 inhibitor) for 30 minutes, intracellular concentrations of DIC, DIC-AG, and 4′OH-DIC were determined after further treating cells with 300 μM DIC for 3 hours. The decreased levels of reactive metabolites caused by BOR or SUL pretreatment resulted in decreased lactate dehydrogenase leakage from SCRH, although the formation of covalent protein adducts was not affected.

Conclusion:

These results suggested that both DIC-AG and 4′OH-DIC may be involved in acute cytotoxicity by DIC.

Effects of nonsteroidal anti-inflammatory drugs on the renal excretion of indoxyl sulfate, a nephro-cardiovascular toxin, in rats

Chronic kidney disease (CKD) is a health problem worldwide. Indoxyl sulfate (IS) is a nephro-cardiovascular toxin accumulated in CKD patients and cannot be removed through hemodialysis. The renal excretion of IS was mediated by organic anion transporters (OATs) OAT 1 and OAT 3. Because a number of nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to inhibit OATs, we hypothesize that NSAIDs might inhibit the renal excretion of IS. Rats were intravenously injected IS with and without diclofenac, ketoprofen or salicylic acid, individually. Blood samples were collected at predetermined time points and the concentrations of IS were determined by HPLC method. The results showed that diclofenac and ketoprofen at 10.0mg/kg significantly decreased the systemic clearance of IS by 71% and 82%, and increased the MRT of IS by 106% and 105%, respectively, whereas salicylic acid did not exhibit significant effects. Cell studies indicated that diclofenac and ketoprofen inhibited the uptake of IS mediated by OAT 1 and OAT 3. In conclusion, diclofenac and ketoprofen inhibited the excretion of IS through inhibition on OAT 1 and OAT 3.

No Benefit of Oral Diclofenac on Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis

BACKGROUND

Pancreatitis following endoscopic retrograde cholangiopancreatography (ERCP) is a serious complication. Rectal diclofenac (100 mg) has been shown to reduce the incidence of pancreatitis; however, this dosage form is unavailable in several countries.

AIMS

We aimed to investigate the preventive effect of oral diclofenac on pancreatitis after ERCP in a multicenter, randomized, prospective, placebo-controlled, double-blind trial.

METHODS

Patients undergoing a first ERCP in seven high-volume centers between July 2012 and August 2014 were considered eligible. Participants were administered oral diclofenac (50 mg) or placebo before and after ERCP. The primary endpoint was the incidence of pancreatitis. A subgroup analysis was performed for patients at high or low risk of pancreatitis. Secondary endpoints were pancreatic enzyme levels (amylase and lipase).

RESULTS

We initially enrolled 430 patients (216 in the diclofenac and 214 in the placebo group), and 23 were excluded after randomization. The overall incidence of pancreatitis was 9.8 % (20/205) and 9.4 % (19/202) in the diclofenac and placebo groups, respectively (p = 0.90). The incidence of pancreatitis was 20.3 % (13/64) and 21.3 % (13/61) in patients at high risk of pancreatitis (p = 0.78) and 5.0 % (7/141) and 4.3 % (6/141) in patients at low risk of pancreatitis in the diclofenac and placebo groups (p = 0.94), respectively. There were no significant differences in serum amylase and lipase levels between the two groups before and 24 h after ERCP.

CONCLUSIONS

Oral administration of diclofenac before and after ERCP showed no benefit in the prevention of pancreatitis.

CLINICAL TRIALS REGISTRY NO

UMIN000008109.

Single intramuscular injection of diclofenac sodium in febrile pediatric patients

Objectives:

There are few reports on the effectiveness and safety of intramuscular (IM) antipyretic injections in pediatric patients. This study reports the efficacy and adverse effects of a single IM injection of diclofenac sodium in pediatric patients.

Materials and Methods:

This was an observational study in which records of febrile pediatric patients presenting to the emergency department were analyzed. Subjects included pediatric patients presenting to the emergency department with a temperature of 38°C or higher. Infants under 12 months of age were excluded. Patients were excluded if they received antipyretics within 4 h prior to presenting to the emergency department. Body temperature was measured at 30–60 min intervals following diclofenac sodium injections. Fever alleviation was defined as the temperature decline to 1°C below the temperature at presentation. Patients who received diclofenac sodium twice or more on different days were observed for side effects such as allergic reaction. Records from the emergency department and outpatient clinics were analyzed.

Results:

The dose of diclofenac sodium injected was approximately 2 mg/kg. The average time elapsed until antipyresis was 69.1 ± 23.8 min. The average temperature reduction after 1 h was 1.1 ± 0.6°C. The average proportion of temperature change after 1 h was 40.6 ± 22.2%. During the period at the emergency department, there were no reported serious side effects.

Conclusions:

A single dose of diclofenac sodium provided effective antipyresis in pediatric patients. Serious side effects were not observed.

Diclofenac Potassium Transdermal Patches Using Natural Rubber Latex Biomembranes as Carrier

The aim of this study was to design a compound transdermal patch containing diclofenac potassium (Dic-K) using natural rubber latex (NRL) biomembrane. The NRL from Hevea brasiliensis is easily manipulated and low cost and presents high mechanical resistance. It is a biocompatible material which can stimulate natural angiogenesis and is capable of adhering cells on its surface. Recent researches have used the NRL for Transdermal Drug Delivery Systems (TDDSs). Dic-K is used for the treatment of rheumatoid arthritis and osteoarthritis and pain relief for postoperative and posttraumatic cases, as well as inflammation and edema. Results showed that the biomembrane can release Dic-K for up to 216 hours. The kinetics of the Dic-K release could be fitted with double exponential function. X-ray diffraction and Fourier Transform Infrared (FTIR) spectroscopy show some interaction by hydrogen bound. The results indicated the potential of the compound patch.

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.

Multidrug Resistance-Associated Protein 3 Plays an Important Role in Protection against Acute Toxicity of Diclofenac

Diclofenac (DCF) is a nonsteroidal anti-inflammatory drug commonly prescribed to reduce pain in acute and chronic inflammatory diseases. One of the main DCF metabolites is a reactive diclofenac acyl glucuronide (DCF-AG) that covalently binds to biologic targets and may contribute to adverse drug reactions arising from DCF use. Cellular efflux of DCF-AG is partially mediated by multidrug resistance-associated proteins (Mrp). The importance of Mrp2 during DCF-induced toxicity has been established, yet the role of Mrp3 remains largely unexplored. In the present work, Mrp3-null (KO) mice were used to study the toxicokinetics and toxicodynamics of DCF and its metabolites. DCF-AG plasma concentrations were 90% lower in KO mice than in wild-type (WT) mice, indicating that Mrp3 mediates DCF-AG basolateral efflux. In contrast, there were no differences in DCF-AG biliary excretion between WT and KO, suggesting that only DCF-AG basolateral efflux is compromised by Mrp3 deletion. Susceptibility to toxicity was also evaluated after a single high DCF dose. No signs of injury were detected in livers and kidneys; however, ulcers were found in the small intestines. Furthermore, the observed intestinal injuries were consistently more severe in KO compared with WT. DCF covalent adducts were observed in liver and small intestines; however, staining intensity did not correlate with the severity of injuries, implying that tissues respond differently to covalent modification. Overall, the data provide strong evidence that (1) in vivo Mrp3 plays an important role in DCF-AG disposition and (2) compromised Mrp3 function can enhance injury in the gastrointestinal tract after DCF treatment.

A Comparative Study of the Efficacy of IV Dexketoprofen, Lornoxicam, and Diclophenac Sodium on Postoperative Analgesia and Tramadol Consumption in Patients Receiving Patient-Controlled Tramadol

OBJECTIVE

This study was designed to compare the effects of dexketoprofen, lornoxicam, and diclophenac sodium on postoperative analgesia and tramadol consumption in patients receiving postoperative patient-controlled tramadol after a major abdominal surgery.

METHODS

Eighty patients were randomized to receive one of the four study drugs. Patients in group dexketoprofen (DT) received IV 50 mg dexketoprofen, group lornoxicam (LR) received IV 8 mg lornoxicam, group diclophenac sodium (DS) received 75 mg IV diclophenac sodium and group saline (S) received 0.9% saline in 2 mL syringes, 20 min before the end of anaesthesia. A standardized (1 mg kg(-1)) dose of tramadol was routinely administered to all patients as the loading dose at the end of surgery. Postoperatively, whenever patients requested, they were allowed to use a tramadol patient-controlled analgesia device giving a bolus dose (0.2 mg kg(-1)) of tramadol. Pain, discomfort, and sedation scores, cumulative tramadol consumption, supplemental meperidine requirement, and side effects were recorded.

RESULTS

Visual rating scale and patient discomfort scores were significantly lower in DT, LR and DS groups compared to those in in group S (p<0.001). Cumulative tramadol consumption was significantly lower in non-steroidal anti-inflammatory drug (NSAID)-treated groups at each study period after the second postoperative hour than in group S (p<0.001). Supplemental meperidine requirement was significantly higher in group S at each study period after postoperative 30 min than in NSAID-treated groups (p<0.01).

CONCLUSION

After major abdominal surgery, adding IV diclophenac, lornoxicam or dexketoprofen to patient-controlled tramadol resulted in lower pain scores, smaller tramadol consumption, less rescue supplemental analgesic requirement, and fewer side effects compared with the tramadol alone group.

A prodrug approach involving in situ depot formation to achieve localized and sustained action of diclofenac after joint injection

Long-acting nonsteroidal anti-inflammatory drug formulations for intra-articular injection might be effective in the management of joint pain and inflammation associated sports injuries and osteoarthritis. In this study, a prodrug-based delivery system was evaluated. The synthesized diclofenac ester prodrug, a weak base (pKa 7.52), has relatively high solubility at low pH (6.5 mg mL(-1) at pH 4) and much lower solubility at physiological pH (4.5 μg mL(-1) at pH 7.4) at 37°C. In biological media including 80% (v/v) human synovial fluid (SF), the prodrug was cleaved to diclofenac mediated by esterases. In situ precipitation of the prodrug was observed upon addition of a concentrated slightly acidic prodrug solution to phosphate buffer or SF at pH 7.4. The degree of supersaturation accompanying the precipitation process was more pronounced in SF than in phosphate buffer. In the rotating dialysis cell model, a slightly acidic prodrug solution was added to the donor cell containing 80% SF resulting in a continuous appearance of diclofenac in the acceptor phase for more than 43 h after an initial lag period of 8 h. Detectable amounts of prodrug were found in the rat joint up to 8 days after knee injection of the acidic prodrug solution.

Formulation of diclofenac for dermal delivery

Diclofenac (DF) was first synthesized in the 1960's and is currently available as ophthalmic, oral, parenteral, rectal and skin preparations. This review focuses on the administration of DF to the skin. As a member of the non-steroidal anti-inflammatory (NSAID) group of drugs the primary indications of DF are for the management of inflammation and pain but it is also used to treat actinic keratosis. The specific aims of this paper are to: (i) provide an overview of the pharmacokinetics and metabolism of DF following oral and topical administration; (ii) examine critically the various formulation approaches which have been investigated to enhance dermal delivery of DF; and (iii) identify new formulation strategies for enhanced DF skin penetration.

Pharmacokinetic interactions between rebamipide and selected nonsteroidal anti-inflammatory drugs in rats

Nonsteroidal anti-inflammatory drugs (NSAIDs) cause gastrointestinal and renal side effects. Rebamipide is a mucoprotective agent that reduces gastrointenstinal side effects when administered concomitantly with NSAIDs. In this study, we investigated the pharmacokinetic drug interactions of rebamipide with two selected NSAIDs, celecoxib or diclofenac. Rats were randomly divided into five groups. Two groups received placebo and three groups were administered rebamipide (30 mg/kg) orally twice daily for two days. On day 3, the animals treated with placebo received celecoxib (40 mg/kg) or diclofenac (10mg/kg) and rats receiving rebamipide were administerd rebamipide followed by a single dose of placebo, celecoxib, or diclofenac. To investigate drug protein interactions, blank rat plasma was spiked with known concentrations of rebamipide, diclofenac plus rebamipide, or celecoxib plus rebamipide then dialyzed through a Rapid Equilibrium Dialysis device. AUC (139.70±24.97 μg h/mL), Cmax (42.99±2.98 μg/mL), and CLoral (0.08±0.02 L/h/kg) values of diclofenac in diclofenac plus rebamipide group altered when compared to those of diclofenac treated groups. Treatment with rebamipide showed no significant change in pharmacokinetic parameters of celecoxib treated rats. Cmax (7.80±1.22 μg/mL), AUC (56.46±7.30 μg h/mL), Vd/F (7.55±1.37 L/kg), and CLoral (0.58±0.09 L/h/kg) of rebamipide were significantly altered when diclofenac was co-administered with rebamipide. Pharmacokinetic parameters of rebamipide plus celecoxib group were not significantly different from those of rebamipide group. Plasma protein binding was not affected by concomitant administration of another drug. These results indicate alteration of pharmacokinetic parameters of both rebamipide and diclofenac when co-administered and cannot be explained by a variation in plasma protein binding.

Absorption and bioavailability of diclofenac after rectal administration of diclofenac-na gel preparation in rat and man

In order to evaluate diclofenac-Na (DC-Na) micro-enema, DC-Na gel preparations were administered to rats and man. When DC-Na gel preparations were rectally administered at various pH (pH 5- 8) to rats, their bioavailability increased at higher pH. The bioavailability of DC-Na gel preparations (pH 8.0) in rats was significantly higher than that with conventional suppository bases, Witepsol H-15 and polyethylene glycol 1000 (PEG 1000). In man, the DC-Na gel preparation showed higher Cmax and higher bioavailability than commercial suppository made with an oily base. DC-Na gel preparations containing 10% v/v oleic acid showed a prolonged action. The irritative effect of DC-Na gel preparation on rectal mucosa in rats was weaker than that of PEG 1000, but similar to that of Witepsol H-15. Therefore, the present results suggest that gel preparation is a favorable form for rectal administration of diclofenac-Na.

Drug interactions of diclofenac and its oxidative metabolite with human liver microsomal cytochrome P450 1A2-dependent drug oxidation

1.  The purpose of this study was to investigate the inhibitory effects of diclofenac on human cytochrome P450 1A2-, 2C19- and 3A4-mediated drug oxidations and to evaluate the drug interaction potential of diclofenac and 4'-hydroxydiclofenac. 2.  Diclofenac was converted to 4'-hydroxydiclofenac by recombinantly expressed human P450 1A2 with Km and Vmax values of 33 µM and 0.20 min(-1), respectively. Diclofenac and 4'-hydroxydiclofenac suppressed flurbiprofen 4'-hydroxylation by P450 2C9 strongly and moderately, respectively; however, they did not affect P450 2C19-dependent S-mephenytoin hydroxylation or P450 3A4-dependent midazolam hydroxylation. 3.  Although the caffeine 3-N-demethylation activity of liver microsomal P450 1A2 was inhibited by simultaneous incubation with diclofenac, the riluzole N-hydroxylation activities of recombinant P450 1A2 and human liver microsomes were inhibited after preincubation with diclofenac or 4'-hydroxydiclofenac for 20 min in the presence of NADPH. Using the inhibition constant (37 µM) of diclofenac on caffeine 3-N-demethylation and the reported 95th percentiles of maximum plasma concentration (10.5 µM) after an oral dose of diclofenac, the in vivo estimated increase in area under the plasma concentration-time curve was 29%. 4.  These results suggest that diclofenac could inhibit drug clearance to a clinically important degree that depends on P450 1A2. Clinically relevant drug interactions in vivo with diclofenac are likely to be invoked via human P450 1A2 function in addition to those caused by the effect of diclofenac on P450 2C9.

Molecular mechanism of diclofenac hepatotoxicity: Association of cell injury with oxidative metabolism and decrease in ATP levels

A certain number of case reports of adverse hepatic reactions to diclofenac are known, suggesting that diclofenac-associated hepatitis may be more common than previously recognized. In order to discriminate among possible molecular mechanisms of toxicity, the following were investigated: (a) cytotoxicity of diclofenac on metabolizing (rat hepatocytes) and non-metabolizing hepatic cells (HepG2, FaO); (b) changes in calcium homoeostasis, glutathione (GSH), lipid peroxidation and ATP levels, and (c) diclofenac metabolism in relation to cytotoxicity. The results indicate that toxicity is associated with the oxidative metabolism of the drug, and correlated with the formation of a minor oxidation metabolite. Inhibitors of diclofenac metabolism concomitantly reduced the toxicity of the drug. Hepatocyte injury was preceded by a decrease in ATP levels. No oxidative stress (no changes in GSH, no lipid peroxidation) could be demonstrated at this early stage. Cytotoxicity was prevented when cells were incubated with fructose, suggesting that the inability of mitochondria to produce ATP is the probable cause of diclofenac hepatotoxicity.

Biotransformation of diclofenac and effects on the metabolome of primary human hepatocytes upon repeated dose exposure

In vitro repeated dose testing for the assessment of chronic drug-induced effects is a huge challenge in preclinical pharmaceutical drug development. Chronic toxicity results in discontinuation of therapy or post-marketing withdrawal of drugs despite in vivo preclinical screening. In case of hepatotoxicity, due to limited long term viability and functionality of primary hepatocytes, chronic hepatic effects are difficult to detect. In this study, we maintained primary human hepatocytes in a serum-free cultivation medium for more than 3 weeks and analyzed physiology, viability and drug metabolizing capacities of the hepatocytes. Moreover, we assessed acute (24 h) diclofenac toxicity in a range of (10-1000 μM) concentrations. The chronic (9 repeated doses) toxicity at one clinically relevant and another higher concentration (6.4 and 100 μM) was also tested. We investigated phase I and II metabolism of diclofenac upon repeated dose exposure and analyzed effects on the cellular exometabolome. Acute 24 h assessment revealed toxicity only for the highest tested concentration (1 mM). Upon repeated dose exposure, toxic effects were observed even at a low, clinically relevant concentration (6.4 μM). Biotransformation pathways were active for 3 weeks and diclofenac-acylglucuronide was detected as the predominant metabolite. Dose dependent diclofenac-induced effects on exometabolome, such as on the production of lactate and 3-hydroxybutyric acid as well as glucose and galactose metabolism, were observed upon nine repeated doses. Summarizing, we show that repeated dose testing on long-term functional cultures of primary human hepatocytes may be included for the assessment of long term toxic effects in preclinical screening and can potentially help replace/reduce in vivo animal testing.

Biowaiver monographs for immediate release solid oral dosage forms: diclofenac sodium and diclofenac potassium

Literature data are reviewed regarding the scientific advisability of allowing a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing either diclofenac potassium and diclofenac sodium. Within the biopharmaceutics classification system (BCS), diclofenac potassium and diclofenac sodium are each BCS class II active pharmaceutical ingredients (APIs). However, a biowaiver can be recommended for IR drug products of each salt form, due to their therapeutic use, therapeutic index, pharmacokinetic properties, potential for excipient interactions, and performance in reported BE/bioavailability (BA) studies, provided: (a) test and comparator contain the same diclofenac salt; (b) the dosage form of the test and comparator is identical; (c) the test product contains only excipients present in diclofenac drug products approved in ICH or associated countries in the same dosage form, for instance as presented in this paper; (d) test drug product and comparator dissolve 85% in 30 min or less in 900 mL buffer pH 6.8, using the paddle apparatus at 75 rpm or the basket apparatus at 100 rpm; and (e) test product and comparator show dissolution profile similarity in pH 1.2, 4.5, and 6.8.

Formulation and Biopharmaceutical Evaluation of Osmotic Matrix Tablets of Diclofenac Sodium

The objective of our study was to prepare and evaluate osmotic matrix (OM) tablets of diclofenac sodium (DS). In vitro studies were done on USPXXIV dissolution apparatus II in different release medium. Surface characteristics of coating films and osmotic contribution of OM tablets also were studied. In vivo evaluation was carried out in 6 healthy human volunteers using HPLC method to assay plasma samples, and the results were compared with the performance of fabricated matrix and two commercial tablets of DS. Through in vitro drug release kinetics, using regression coefficient analysis and Peppas equation, different pharmacokinetic parameters and relative bioavailability were determined. OM tablets were found to provide more prolonged and controlled therapeutic plasma DS levels and also showed improved bioavailability in comparison to fabricated matrix and commercial tablets studied.

Isolation and characterization of a new human urinary metabolite of diclofenac applying LC-NMR-MS and high-resolution mass analyses

The nonsteroidal anti-inflammatory drug diclofenac is widely used. Diclofenac is extensively metabolized to several hydroxylated derivatives and their conjugates. The lactam-dehydrate of 4'-hydroxy diclofenac (4'-OHDD) has now been detected as a new urinary metabolite of diclofenac. Isolation was successfully performed using preparative HPLC in three different steps using water, methanol, and acetonitrile, respectively. The structural characterization of 4'-OHDD was achieved by LC-NMR-MS. In addition, specific mass fragmentation pattern could be obtained using LC-high-resolution MS with both positive and negative electrospray ionization.

Persistence of NSAIDs at effect sites and rapid disappearance from side-effect compartments contributes to tolerability

BACKGROUND

Non-steroidal, anti-inflammatory drugs (NSAIDs) are still the most widely used drugs worldwide. The introduction of selective cyclooxygenase (COX)-2 inhibitors has led to compounds which appear less damaging to the gastrointestinal tract, but possibly more risky to the cardiovascular system than older drugs. None has as yet reached OTC-status.

OBJECTIVE

This situation necessitates an analysis of the characteristics of those older ones which - due to their relative safety - have achieved over-the-counter (OTC) status.

DESIGN

The pharmacodynamic and pharmacokinetic characteristics of non-selective COX inhibitors in OTC use were obtained from the literature by systematic search, examined and used to construct a coherent hypothesis why they achieved OTC status, i.e. effectiveness and relative safety at low doses.

RESULTS

Pharmacodynamic (COX-2 preferential, but not selective inhibition) and, more importantly, pharmacokinetic characteristics of some of the older compounds may make them particularly safe drugs if used at low (OTC) doses with treatment limited to a few days of intake. The reason why some NSAIDs are particularly active while being relatively free from side-effects may be due to their specific biodistribution and metabolism, leading to drug accumulation and persistence in inflamed tissue (effect compartment) together with fast clearance from the central compartment, including blood, vascular wall, heart and kidney, i.e., possible sideeffect compartments.

CONCLUSION

This specific pharmacokinetic behavior of some non-selective COX inhibitors, such as diclofenac and ibuprofen, may explain why these widely used, non-steroidal, anti-inflammatory compounds are relatively well suited for OTC use and why some are more appropriate for the therapy of certain pain conditions than others.

Diclofenac potassium 12.5mg tablets for mild to moderate pain and fever: a review of its pharmacology, clinical efficacy and safety

Non-prescription (over-the-counter [OTC]) analgesics are used for the short-term treatment of acute painful conditions of mild to moderate intensity in everyday life. Well documented safety and efficacy, a rapid onset of action and a flexible daily dosing regimen are essential in this context. Film-coated, immediate-release, low-dose diclofenac potassium, developed for OTC use, offers a flexible daily dosing regimen with an initial dose of two tablets (2 x 12.5mg) followed by one or two tablets up to a maximum daily dose of six tablets (75 mg/day). The maximum plasma drug concentration is reached 30 minutes after administration, and the mean terminal half-life is 1-2 hours, allowing a 4- to 6-hour duration of activity, depending on the condition. Thirteen randomised, double-blind trials with both placebo and active controls have demonstrated the efficacy of diclofenac potassium 12.5mg tablets in conditions suitable for treatment with OTC medication, for example, acute lower back pain, headache, acute pain after dental extraction, symptoms of cold and influenza (including fever), and dysmenorrhoea. A single dose of diclofenac potassium 12.5mg is the lowest recommended effective dose. A two-tablet single dose of 25mg is at least as effective as ibuprofen 400mg. A flexible dosing regimen of an initial two tablets followed by one or two tablets up to a total daily dose of 75 mg is as effective as ibuprofen used in comparable fashion up to a total daily dose of 1200 mg. The incidence of adverse events in patients taking single or multiple doses of diclofenac potassium is similar to that of ibuprofen and placebo. In a safety study conducted to compare diclofenac potassium with ibuprofen for up to 3 months in patients with osteoarthritis of the knee, no differences in the pattern of adverse events were noted. There was no evidence of either hepatic injury or cardiovascular safety-related issues at any time during the study. Patients are generally capable of taking diclofenac potassium appropriately. A maximum OTC treatment duration of 5 days for pain and 3 days for fever is recommended.

Diclofenac sodium in the treatment of osteoarthritis

Diclofenac is a well-tolerated, traditional nonsteroidal anti-inflammatory drug that has been shown to be very effective for the treatment of osteoarthritis. Serendipitously, diclofenac has been shown to be relatively selective for cyclooxygenase-2; perhaps due to that fact, it has proven to be well tolerated. Tolerance and utility have been augmented with a variety of formulations, including extended-release tablets, a combination tablet with misoprostol, a suppository preparation and a topically absorbed solution. Sodium diclofenac tablets are available in 25 and 50 mg units, the extended-release tablets are available in 75 and 100 mg units, and the suppositories in 50 and 100 mg units. The usual daily dose ranges from 75 to 150 mg, ingested as two or three divided doses. The drug is a phenylacetic acid derivative. Although it is completely absorbed, only 60% is thought to reach the systemic circulation due to first-pass metabolism. The area under the plasma concentration curve is proportional to the dose in the range of 25–150 mg.