Pharmacokinetic evaluation of a new oral sustained release dosage form of tramadol

Green micelle and complex inclusion enhance synchronous spectrofluorimetric quantification of a novel analgesic combination: Tramadol and celecoxib in tablet dosage form and spiked human plasma

This work offers for the first time an optimized, highly sensitive, simple, and accurate synchronized spectrofluorimetric technique for the simultaneous measurement of tramadol and celecoxib in powder form, their combined multimodal tablet, and finally spiked human plasma samples. Tramadol and celecoxib were recently released as a new drug combination to alleviate intense, sudden pain when other pain medications had failed. The technique entailed taking measurements of the fluorescence amplitudes of the synchronized spectra at Δλ = 100 nm. Excitation was made at 220 nm and 264 nm, whereas the emission points were 282 nm and 368 nm for tramadol and celecoxib, respectively. This technique offers linearity of 40-400 ng/ml and 100-2000 ng/ml for tramadol and celecoxib, respectively. Complex formation between the cited medications with the surfactant sodium dodecyl sulphate enhanced the fluorescence intensity and other control parameters. Tramadol and celecoxib were both determined in spiked human plasma using the current technique with marked percentage recoveries of 98.63 ± 6.30% and 99.32 ± 6.67%, respectively. Last, the research was extended to check the greenness profile of the finally optimized method and the results revealed excellent eco-friendliness. Three greenness assessment tools were used including Eco-scale, the Green Analytical Procedure Index tool, and the AGREE calculator. Sustainable development, economic feasibility, and environmental soundness were all considered throughout the development of the present technique. The approach was validated in accordance with the requirements provided by the International Council for Harmonization.

Bimodal Release Two-In-One Clonazepam Matrix Lozenge Tablets for Managing Anxiety-Related Disorders: Formulation, Optimization and In Vivo Evaluation

Clonazepam (CLZ), an antipsychotic drug reported for its efficiency in managing anxiety-related disorders, is being marketed only as conventional tablets. Some patients have abstention to swallow the conventional tablets; therefore, the proposed study was aimed at developing a buccal lozenge tablet by direct compression of two types of optimized granules. Conazepam’s water solubility was first enhanced by a solid dispersion technique for a fast and better dissolution of type 1 granules, while the impact of gelling polymers was investigated on controlled-release type 2 granules. The optimized formulae met the acceptable pharmacopeial limits for tablets’ evaluation. A differential scanning calorimetry study revealed the compatibility between the drug and used excipients. All formulae gave a burst release of CLZ in the first hour of investigation, followed by a sustained release over 24 h. The formula that showed the highest prolonged in vitro release (99.0 + 0.1%), following the Higuchi diffusion model (R2 = 0.99), was then selected for further study. The formula succeeded in controlling the induced stress in a rat model with a significant impact on the behavioral tests throughout the experiment. The results were further confirmed by a pharmacokinetic study that showed a significant increase in Cmax, Tmax, and AUC (1.5, 2, and 3.9 folds), respectively, compared to oral suspension. The newly proposed delivery system has proven a better efficacy with a reduced dosing frequency.

Enhancing Atorvastatin In Vivo Oral Bioavailability in the Presence of Inflammatory Bowel Disease and Irritable Bowel Syndrome Using Supercritical Fluid Technology Guided by wbPBPK Modeling in Rat and Human

Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are common disorders that can change the body's physiology and drugs pharmacokinetics. Solid dispersion (SD) preparation using supercritical fluid technology (SFT) has many advantages. Our study aimed to explore the effect of IBS and IBD on atorvastatin (ATV) pharmacokinetics, enhance ATV oral bioavailability (BCS II drug) using SFT, and analyze drug-disease-formulation interaction using a whole-body physiologically based pharmacokinetic (wbPBPK) model in rat and human. A novel ATV formulation was prepared using SFT and characterized in vitro and in vivo in healthy, IBS, and IBD rats. The resulting ATV plasma levels were analyzed using a combination of conventional and wbPBPK approaches. The novel formulation increased ATV solubility by 20-fold and resulted in a zero-order release of up to 95%. Both IBS and IBD increased ATV exposure after oral and intravenous administration by more than 30%. The novel SFT formulation increased ATV bioavailability by 28, 14, and 18% in control, IBD, and IBD rat groups and resulted in more consistent exposure as compared to raw ATV solution. Higher improvements in ATV bioavailability of more than 2-fold upon receiving the novel SFT formulation were predicted by the human wbPBPK model as compared to receiving the conventional tablets. Finally, the established wbPBPK model could describe ATV ADME in the presence of IBS and IBD after oral administration of raw ATV and using the novel SFT formula and can help scale the optimized ATV dosing regimens in the presence of IBS and IBD from rats to humans.

Tapentadol Versus Tramadol: A Narrative and Comparative Review of Their Pharmacological, Efficacy and Safety Profiles in Adult Patients

We conducted a narrative review of the literature to compare the pharmacological, efficacy and safety profiles of tapentadol and tramadol, and to assess the clinical interest of tapentadol in adult patients. Tapentadol and tramadol share a mixed mechanism of action, including both mu-agonist and monoaminergic properties. Tapentadol is approximately two to three times more potent than tramadol and two to three times less potent than morphine. It has no identified analgesically active metabolite and is not significantly metabolised by cytochrome P450 enzymes, thus overcoming some limitations of tramadol, including the potential for pharmacokinetic drug-drug interactions and interindividual variability due to genetic polymorphisms of cytochrome P450 enzymes. The toxicity profiles of tramadol and tapentadol are similar; however tapentadol is likely to result in less exposure to serotoninergic adverse effects (nausea, vomiting, hypoglycaemia) but cause more opioid adverse effects (constipation, respiratory depression, abuse) than tramadol. The safety of tapentadol in real-world conditions remains poorly documented, particularly in at-risk patient subgroups and also in the ability to assess the risk associated with its residual serotonergic activity (serotonin syndrome, seizures). Because of an earlier market introduction, more real-world safety data are available for tramadol, including data from at-risk patient subgroups. The level of evidence on the efficacy of both tramadol and tapentadol for the treatment of chronic pain is globally low. The trials published to date show overall that tapentadol does not provide a clinically significant analgesic improvement compared to existing treatments, for which the safety profile is much better known. In conclusion, tapentadol is not a first-line opioid but represents an additional analgesic in the therapeutic choices, which some patients may benefit from after careful examination of their clinical situation, co-morbidities and co-medications.

Physiologically based pharmacokinetic modeling of tramadol to inform dose adjustment and drug-drug interactions according to CYP2D6 phenotypes

OBJECTIVES

The objective of this study was to establish physiologically based pharmacokinetic (PBPK) models of tramadol and its active metabolite O-desmethyltramadol (M1) and to explore the influence of CYP2D6 gene polymorphism on the pharmacokinetics of tramadol and M1. Furthermore, we used PBPK modeling to prospectively predict the extent of drug-drug interactions (DDIs) in the presence of genetic polymorphisms when tramadol was co-administered with the CYP2D6 inhibitors duloxetine and paroxetine.

METHODS

Plasma concentrations of tramadol and M1 were used to adjust the turnover frequency (K_cat ) of CYP2D6 for phenotype populations with different CYP2D6 genotypes. PBPK models were developed to capture the pharmacokinetics between CYP2D6 extensive metabolizers (EMs), intermediate metabolizers (IMs), poor metabolizers (PMs), and ultra-rapid metabolizers (UMs). The validated models were then used to support dose adjustment in different CYP2D6 phenotypes and to predict the extent of CYP2D6-mediated DDIs when tramadol was co-administered with paroxetine or duloxetine.

RESULTS

The PBPK models we built accurately describe tramadol and M1 exposure in the population with different CYP2D6 phenotypes. In our prediction, the area under the concentration-time curve (AUC_inf-tDlast ) of M1 is 70% lower in PMs than in EMs, 27% lower in IMs, and 15% higher in UMs. Based on the models we built, we suggest that the oral dose of tramadol should be 50% higher for IMs and 25% lower for UMs to achieve an approximately equivalent plasma exposure of M1 as in EMs. When tramadol was co-administered with paroxetine or duloxetine, the magnitude of the inhibitor-substrate interaction was lowest in EMs (0.45), secondary in IMs (0.39), and highest in PMs (0.18) in terms of M1.

CONCLUSION

The current example uses the PBPK model to guide dose adjustment of tramadol and to predict the effect of CYP2D6 genetic polymorphisms on DDIs for rational clinical use of tramadol in the future.

High-amylose sodium carboxymethyl starch matrices: development and characterization of tramadol hydrochloride sustained-release tablets for oral administration

Substituted amylose (SA) polymers were produced from high-amylose corn starch by etherification of its hydroxyl groups with chloroacetate. Amorphous high-amylose sodium carboxymethyl starch (HASCA), the resulting SA polymer, was spray-dried to obtain an excipient (SD HASCA) with optimal binding and sustained-release (SR) properties. Tablets containing different percentages of SD HASCA and tramadol hydrochloride were produced by direct compression and evaluated for dissolution. Once-daily and twice-daily SD HASCA tablets containing two common dosages of tramadol hydrochloride (100 mg and 200 mg), a freely water-soluble drug, were successfully developed. These SR formulations presented high crushing forces, which facilitate further tablet processing and handling. When exposed to both a pH gradient simulating the pH variations through the gastrointestinal tract and a 40% ethanol medium, a very rigid gel formed progressively at the surface of the tablets providing controlled drug-release properties. These properties indicated that SD HASCA was a promising and robust excipient for oral, sustained drug-release, which may possibly minimize the likelihood of dose dumping and consequent adverse effects, even in the case of coadministration with alcohol.

Review of extended-release formulations of Tramadol for the management of chronic non-cancer pain: focus on marketed formulations

Patients with chronic non-malignant pain report impairments of physical, social, and psychological well-being. The goal of pain management should include reducing pain and improving quality of life. Patients with chronic pain require medications that are able to provide adequate pain relief, have minimum dosing intervals to maintain efficacy, and avoid breakthrough pain. Tramadol has proven efficacy and a favourable safety profile. The positive efficacy and safety profile has been demonstrated historically in numerous published clinical studies as well as from post-marketing experience. It is a World Health Organization “Step 2” opioid analgesic that has been shown to be effective, well-tolerated, and valuable, where treatment with strong opioids is not required. A number of extended release formulations of Tramadol are available in Canada and the United States. An optimal extended release Tramadol formulation would be expected to provide consistent pain control with once daily dosing, few sleep interruptions, flexible dosing schedules, and no limitation on taking with meals. Appropriate treatment options should be based on the above proposed attributes. A comparative review of available extended release Tramadol formulations shows that these medications are not equivalent in their pharmacokinetic profile and this may have implications for selecting the optimal therapy for patients with pain syndromes where Tramadol is an appropriate analgesic agent. Differences in pharmacokinetics amongst the formulations may also translate into varied clinical responses in patients. Selection of the appropriate formulation by the health care provider should therefore be based on the patient’s chronic pain condition, needs, and lifestyle.

Pharmacokinetics and physiological effects of repeated oral administrations of tramadol in horses

This study evaluated the pharmacokinetics and physiological effects of tramadol during repeated oral administrations in horses. Nine adult healthy horses were administered tramadol at 5 and 10 mg/kg orally every 12 h for 5 days in a randomized, crossover design with a 3-week washout between treatments. Plasma concentrations of tramadol, O- and N-desmethyltramadol (M1 and M2) were measured using Liquid-Chromatography-Mass Spectrometry at predetermined time points following each tramadol administration. Cardiovascular, respiratory and gastrointestinal physiological variables were monitored and adverse events were recorded. Data were analysed with two-way repeated measures anova or Kruskal-Wallis one-way anova on ranks with P < 0.05 considered statistically significant. There were no significant effects of tramadol on the physiological variables. One horse receiving 10 mg/kg tramadol developed mild colic. Following tramadol at 5 and 10 mg/kg, respectively, maximum plasma concentrations (Cmax ) of tramadol ranged from 82-587 and 127-1280 ng/mL, nonconjugated M1 ranged from 2.51-26.7 and 4.88-34.3 ng/mL, and nonconjugated M2 from 12.5-356 and 35.4-486 ng/mL. Corresponding minimum plasma concentrations (Cmin ) of tramadol at 12 h following each dose ranged from 0.8-24 and 3-117 ng/mL. Tramadol accumulated considerably over time, more markedly when given at 10 mg/kg than at 5 mg/kg (accumulation indexes of 3.51 and 1.73 respectively). There was no accumulation of M1 but substantial accumulation of M2. In conclusion, there was accumulation and increase in exposure to tramadol and M2, but not M1, during repeated oral administrations in horses.

Tramadol Extended-Release for the Management of Pain due to Osteoarthritis

Current knowledge on pathogenesis of osteoarticular pain, as well as the consequent several, especially on the gastrointestinal, renal, and cardiovascular systems, side effects of NSAIDs, makes it difficult to perform an optimal management of this mixed typology of pain. This is especially observable in elderly patients, the most frequently affected by osteoarthritis (OA). Tramadol is an analgesic drug, the action of which has a twofold action. It has a weak affinity to mu opioid receptors and, at the same time, can result in inhibition of the reuptake of noradrenaline and serotonin in nociceptorial descending inhibitory control system. These two mechanisms, "opioidergic" and "nonopioidergic," are the grounds for contrasting certain types of pain that are generally less responsive to opioids, such as neuropathic pain or mixed OA pain. The extended-release formulation of tramadol has good efficacy and tolerability and acts through a dosing schedule that allows a high level of patients compliance to therapies with a good recovery outcome for the patients' functional status.

Application of organogels as oral controlled release formulations of hydrophilic drugs

We previously demonstrated that organogels prepared from soybean oil using 12-hydroxy stearic acid as a gelator can slowly release ibuprofen, a model lipophilic drug. In this study, we investigated the applicability of organogels as controlled release formulations of hydrophilic drugs. The release rates of theophylline and ofloxacin, which are used as model hydrophilic drugs, were significantly slower than those of ibuprofen and antipyrine (model lipophilic drugs). Furthermore, no erosion was noted during drug release from organogels. Lipophilic drug molecules are released after diffusion in organogels because all molecules fully dissolve in the gel. On the other hand, hydrophilic drug molecules need to be dissolved before they diffuse in the organogel, prior to their release from the gel. Therefore, it is speculated that the release rates of hydrophilic drugs are slower than those of lipophilic drugs. To confirm the usefulness of organogels in controlled release formulations in vivo, organogels containing ibuprofen, ofloxacin, theophylline or antipyrine were intraduodenally administered to rats. All drugs used in this study were rapidly absorbed when administered in aqueous suspensions. In contrast, the drug concentrations in plasma after administration in organogels were lower; however, the lower concentrations of drugs sustained for 10 h after administration. With organogel administration, the mean residence time of drugs was longer than that with aqueous suspension administration. In conclusion, organogels are potential candidates for controlled release formulations of not only lipophilic drugs, but also hydrophilic drugs.

Pharmacokinetics of tramadol hydrochloride and its metabolite O-desmethyltramadol in peafowl (Pavo cristatus)

Tramadol is a centrally acting opiate analgesic that has not been well studied in avian species. Tramadol and its metabolites exert their effects at multiple sites, including opiate (mu, kappa, and delta), adrenergic (alpha-2), and serotonin (5HT) receptors. This multi-receptor mode of action is advantageous for avian patients because the mechanisms for analgesia have not been fully elucidated in all species. The objective of this study was to document the pharmacokinetics of tramadol and its active metabolite O-desmethyltramadol (M1) in common peafowl (Pavo cristatus). Based on results from a pilot animal, six adult peafowl (three male, three female) judged to be clinically healthy based on physical exam and routine bloodwork were selected for this study. Each bird was anesthetized for placement of a jugular catheter, and 7.5 mg/kg tramadol was administered orally via gavage tube. Blood samples were collected just prior to drug administration; at 30 min; and at 1, 2, 3, 4, 6, 8, 10, 12, 24, and 34 hr. Plasma levels of tramadol and M1 were measured and the pharmacokinetics for each drug was calculated. Although tramadol was quickly metabolized, plasma levels of M1 remained at or near human analgesic levels for 12-24 hr. Based on these data, tramadol may be a practical option as an orally administered analgesic agent in avian patients. Further studies, including antinociceptive studies, are needed.

Tramadol use in zoologic medicine

Numerous analgesics are available for use in animals, but only a few have been used or studied in zoologic species. Tramadol is a relatively new analgesic that is available in an inexpensive, oral form, and is not controlled. Studies examining the effect of tramadol in zoologic species suggest that significant differences exist in pharmacokinetics parameters as well as analgesic dynamics. This article reviews the current literature on the use of tramadol in humans, domestic animals, and zoologic species.

Adverse event profile of tramadol in recent clinical studies of chronic osteoarthritis pain

OBJECTIVE

To review the safety profile of tramadol hydrochloride (tramadol) in the treatment of chronic osteoarthritis pain, with specific reference to the incidence of adverse events (AEs) reported in large clinical trials.

METHODS

An extensive review of published clinical trials with tramadol was conducted, using literature searches in MEDLINE and EMBASE (since 1997) and the key search terms: tramadol, immediate-release (IR), extended-release (ER), sustained-release (SR), chronic pain, and osteoarthritis. Studies were included based on appropriate study design, appropriately reported safety data, and chronic osteoarthritis as a pain condition. Secondary analyses of previously published pain studies were excluded.

RESULTS

Fifteen studies met the inclusion criteria. The most common AEs reported across all tramadol formulations were nausea, dizziness, constipation, vomiting, somnolence, and headache. Most AEs were mild to moderate in severity and occurred more commonly during initial treatment than during maintenance treatment. Differences in the rates of selected gastrointestinal and central nervous system AEs were seen between long-acting and immediate-release tramadol formulations, both within individual studies and across all studies. AEs appeared to be dose-dependent in fixed-dose studies.

CONCLUSIONS

This review provides a robust base for descriptive assessment of AEs associated with long-acting tramadol formulations. Although the actions of different tramadol formulations are biologically similar, differences in pharmacokinetics, drug-release patterns, and availability may influence the incidence of AEs associated with tramadol. Because of the limitations of a qualitative safety analysis across studies with different populations and study designs, any observed differences should be interpreted with caution, but these differences may help educate healthcare providers about tramadol treatment in patients with chronic osteoarthritis pain and help them select the optimal dose for specific patients.

A comparison of long- and short-acting opioids for the treatment of chronic noncancer pain: tailoring therapy to meet patient needs

Management of chronic noncancer pain (CNCP) requires a comprehensive assessment of the patient, the institution of a structured treatment regimen, an ongoing reassessment of the painful condition and its response to therapy, and a continual appraisal of the patient's adherence to treatment. For many patients with CNCP, the analgesic regimen will include opioids. Physicians should consider the available evidence of efficacy, the routes of administration, and the pharmacokinetics and pharmacodynamics of the various formulations as they relate to the temporal characteristics of the patient's pain. When making initial decisions, physicians should decide whether to prescribe a short-acting opioid (SAO) with a relatively quick onset of action and short duration of analgesic activity, a long-acting opioid (LAO) with a longer duration of analgesic action but a potentially longer onset of action, or both. Studies suggest that SAOs and LAOs are both effective for most types of CNCP. A review of published studies found no data to suggest that either SAOs or LAOs are generally more efficacious for treating any particular CNCP condition. The LAOs may provide more stable analgesia with less frequent dosing; however, opioid therapy should be tailored to the pain state and the individual patient, and SAOs may be appropriate for some patients with CNCP. MEDLINE and PubMed searches were conducted to locate relevant studies published from January 1975 to April 2008 using the following search terms: opioids, short-acting opioids, long-acting opioids, chronic pain, chronic pain AND opioids, and narcotics. English-only randomized controlled trials and nonrandomized studies were considered.

Evaluation of tramadol and its main metabolites in horse plasma by high-performance liquid chromatography/fluorescence and liquid chromatography/electrospray ionization tandem mass spectrometry techniques

Tramadol is a centrally acting analgesic drug that has been used clinically for the last two decades to treat pain in humans. The clinical response of tramadol is strictly correlated to its metabolism, because of the different analgesic activity of its metabolites. O-Desmethyltramadol (M1), its major active metabolite, is 200 times more potent at the micro-receptor than the parent drug. In recent years tramadol has been widely introduced in veterinary medicine but its use has been questioned in some species. The aim of the present study was to develop a new sensible method to detect the whole metabolic profile of the drug in horses, through plasma analyses by high-performance liquid chromatography (HPLC) coupled with fluorimetric (FL) and photodiode array electrospray ionization mass spectrometric (PDA-ESI-MS) detection, after its sustained release by oral administration (5 mg/kg). In HPLC/FL experiments the comparison of the horse plasma chromatogram profile with that of a standard mixture suggested the identification of the major peaks as tramadol and its metabolites M1 and N,O-desmethyltramadol (M5). LC/PDA-ESI-MS/MS analysis confirmed the results obtained by HPLC/FL and also provided the identification of two more metabolites, N-desmethyltramadol (M2), and N,N-didesmethyltramadol (M3). Another metabolite, M6, was also detected and identified. The present findings demonstrate the usefulness and the advantage of LC/ESI-MS/MS techniques in a search for tramadol metabolites in horse plasma samples.

Chronic non-cancer pain: Focus on once-daily tramadol formulations

Despite progress in pain management, chronic non-cancer pain (CNCP) represents still a clinical challenge. The efficacy and safety profile of tramadol make it suitable as a long-term treatment in a variety of CNCP conditions. New once-daily (OD) formulations of tramadol have been marketed in various countries, in order to offer the advantage of a reduced dosing regimen and to improve patients' compliance. This review focuses on the technology, pharmacology, clinical efficacy, and safety of different once-daily tramadol formulations. Hydrophilic vs hydrophobic matrix systems and newer technologies used in once-daily formulations to control drug delivery are discussed. Three randomized controlled trials (RCTs) established OD tramadol analgesic efficacy to be superior to that of placebo for pain management and functional improvement in patients with osteoarthritis. Three RCTs demonstrated similar rates of efficacy between OD tramadol and immediate-release (IR) or sustained-release (SR) formulations, with a better adverse events profile. An open trial on long term tolerability showed that OD tramadol is generally safe in rheumatological pain treatment.

Single- and multiple-dose bioequivalence of two once-daily tramadol formulations using stereospecific analysis of tramadol and its demethylated (M1 and M5) metabolites

OBJECTIVE

To assess bioequivalence of two once-daily formulations of tramadol (T) as well as delineate pharmacokinetics of its enantiomers and those of its main metabolites after single- and multiple-dose administration.

METHODS

Single- and multiple-dose studies were conducted separately each in 48 healthy volunteers using an open-label, randomized, crossover design. Subjects received the 200 mg test (Tramadolor) and reference (Ultram ER) formulations in a randomized manner separated by a 7-day washout period once (single-dose study) or once daily for 7 days (multiple-dose study). Blood was sampled on days 1-2 (single-dose) or days 4-7 (multiple-dose), and plasma samples were analyzed using a stereospecific assay for quantitation of individual enantiomers of T and its active O-demethylated (M1) and N,O-demethylated (M5) metabolites. Bioequivalence was assessed using log-transformation and 90% confidence intervals.

RESULTS

All analytes showed stereoselectivity after single and multiple doses of both products, with average concentrations of (+)-T, (-)-M1, and (-)-M5 exceeding those of their respective antipode. However, a decrease in steady-state oral clearance of T relative to single dose was not stereoselective. In both studies, the formulations were bioequivalent with regard to AUG and Cmax for both enantiomers of all analytes. The Tmax for the reference (10-12 h) was significantly (p < 0.05) longer than that for the test (5-6 h). Degree of fluctuation of T enantiomers after the test was greater than the reference. Both formulations were tolerated relatively well.

CONCLUSIONS

Tramadolor and Ultram ER were bioequivalent for both enantiomers of T, M1 and M5. It is unlikely there would be any significant clinical differences between the two formulations.

Stereospecific high-performance liquid chromatographic analysis of tramadol and its O-demethylated (M1) and N,O-demethylated (M5) metabolites in human plasma

A stereospecific method for simultaneous quantitation of the enantiomers of tramadol (T) and its active metabolites O-demethyl tramadol (M1) and O-demethyl-N-demethyl tramadol (M5) in human plasma is reported. After the addition of penbutolol (IS), plasma (0.5 ml) samples were extracted into methyl tert-butyl ether, followed by back extraction into an acidic solution. The separation was achieved using a Chiralpak AD column with a mobile phase of hexanes:ethanol:diethylamine (94:6:0.2) and a flow rate of 1 ml/min. The fluorescence of analytes was then detected at excitation and emission wavelengths of 275 and 300 nm, respectively. All the six enantiomeric peaks of interest plus three unknown metabolite peaks and IS peak (a total of 10 peaks) eluted within 23 min, free from endogenous interference. The assay was validated in the plasma concentration range of 2.5-250 ng/ml, with a lower limit of quantitation of 2.5 ng/ml, for all the six analytes. The extraction efficiency (n=5) was close to 100% for both T and M1 enantiomers and 85% for M5 and IS enantiomers. The application of the assay was demonstrated by simultaneous measurement of plasma concentrations of T, M1, and M5 enantiomers in a healthy volunteer after the administration of 50 mg oral doses of racemic T.

Pharmacokinetics and dose proportionality of three Tramadol Contramid® OAD tablet strengths

A three-way crossover study in 27 human volunteers was conducted to characterize the pharmacokinetics and to assess the dose proportionality of 100 mg, 200 mg and 300 mg strengths of a novel once-a-day tramadol controlled-release tablet (Tramadol Contramid OAD) following single-dose administration. Serial blood samples were collected at predefined timepoints over a 48 h period and racemic tramadol and O-desmethyltramadol concentrations in plasma were determined using a validated LC-MS/MS method. Pharmacokinetic parameters were derived using noncompartmental methods. Following dose normalization and logarithmic transformation of concentration-dependent parameters, the results were compared using analysis of variance (ANOVA). The residual variability thereby obtained was used to construct 90% classical confidence intervals. The two one-sided tests procedure was used for all pairwise comparisons. Dose proportionality was concluded since the 90% CI for the ratio of geometric means was included in the acceptance range of 0.80-1.25 for all comparisons.

Once-daily tramadol in rheumatological pain

New once-daily formulations of tramadol have been recently marketed in various countries. This review focuses on the matrix systems used in sustained-release formulations to control drug delivery, the pharmacokinetics and pharmacodynamic profile and the available clinical trials on once-daily tramadol. Four controlled clinical studies with a limited number of patients have shown that once-daily tramadol is safe and effective for up to 12 weeks in rheumatological pain treatment, with a favourable side effects profile. Once-daily tramadol has established efficacy superior to that of placebo for pain management and functional improvement in patients with osteoarthritis. Two randomised clinical trials demonstrated similar rates of efficacy between immediate-release and once-daily sustained-release formulation, without significant differences in the use of escape medications and the number of nights woken. Once-daily tramadol offers the advantage of a reduced dosing regimen that improves patient compliance.

An automated and fully validated LC-MS/MS procedure for the simultaneous determination of 11 opioids used in palliative care, with 5 of their metabolites

A fully validated liquid chromatographic procedure coupled with electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) is presented for quantitative determination of the opioids buprenorphine, codeine, fentanyl, hydromorphone, methadone, morphine, oxycodone, oxymorphone, piritramide, tilidine, and tramadol together with their metabolites bisnortilidine, morphine-glucuronides, norfentanyl, and nortilidine in blood plasma after an automatically performed solid-phase extraction (SPE). Separation was achieved in 35 min on a Phenomenex C12 MAX-RP column (4 microm, 150 x 2 mm) using a gradient of ammonium formiate buffer (pH 3.5) and acetonitrile. The validation data were within the required limits. The assay was successfully applied to authentic plasma samples, allowing confirmation of the diagnosis of overdose situations as well as monitoring of patients' compliance, especially in patients under palliative care.

Long-term tolerability of tramadol LP, a new once-daily formulation, in patients with osteoarthritis or low back pain

INTRODUCTION

Tramadol hydrochloride is a centrally acting analgesic, which possesses opioid agonist properties and activates monoaminergic spinal inhibition of pain. An oral, once a day, sustained release formulation of tramadol is thought to be advantageous compared with immediate release preparations as it prevents plasma peaks associated with increased side-effects of the drug. It may also improve compliance. The purpose of the study was to assess the long-term safety of a new sustained-release formulation of tramadol (tramadol LP) in patients with knee or hip osteoarthritis and in patients with refractory low back pain.

STUDY DESIGN

The design was a phase III, open, multicentre, international, tolerability study with tramadol LP at a dose titrated by the patient between 100 and 400 mg once daily, according to the intensity of pain. The treatment was administered for a continuous period of 4 weeks followed by an intermittent intake of 5 months in 204 patients. The safety criteria for evaluation were recording of adverse events, laboratory tests, electrocardiogram, radiography, global tolerability assessed by the patient and the investigators.

RESULTS

Long-term use of tramadol LP was reasonably well tolerated. Most of the reported adverse events were expected and occurred within the first month of treatment. Roughly half of the patients (49%) reported adverse events, of which 66% were related to treatment. Gastrointestinal events (nausea and vomiting) were the most frequent. Serious adverse events were reported in 6.4% of patients, from which only two cases were related to treatment. There was no sign of tolerance development and the percentage of patients presenting withdrawal symptoms after the end of treatment was low (6%).

CONCLUSION

Long-term treatment with tramadol LP once daily is generally safe in patients with osteoarthritis or refractory low back pain.

Efficacy and tolerability of sustained-release tramadolin the treatment of symptomatic osteoarthritis of the hip or knee: A multicenter, randomized, double-blind, placebo-controlled study

BACKGROUND

Opioid analgesics may be a useful alternative in patients with osteoarthritis who have not responded to first-line treatment with acetaminophen and in whom nonsteroidal anti-inflammatory drugs are contraindicated, ineffective, or poorly tolerated.

OBJECTIVE

This study compared the efficacy and tolerability of tramadol LP 200 mg, a new once-daily,sustained-release formulation, with those of placebo in patients with osteoarthritis of the hip or knee.

METHODS

In this multicenter, double-blind, placebo-controlled, parallel-group study, patients with osteoarthritis of the hip or knee (European League Against Rheumatism criteria) were randomized to receive either tramadol LP 200 mg once daily or placebo for 14 days. The primary efficacy end point was the change from baseline to the end of the study in scores on the Huskisson visual analog scale for pain. Secondary end points were change in the Lequesne functional discomfort index, global efficacy assessed by the patient and the investigator, time to improvement, and use of acetaminophen as rescue analgesic medication. Global tolerability was assessed by both patients and investigators at the end of the study The number and severity of adverse events occurring during the study and for 2 weeks thereafter were also recorded.

RESULTS

Two hundred thirty patients (167 women, 63 men) were evaluable for efficacy and safety Demographic data for the tramadol and placebo groups were as follows: mean (SD) age, 67.1 (7.1) and 66.4 (92) years, respectively; female sex, 72.1% and 73.1%; and mean body weight, 74.7 (13.6) and 74.6 (14.8) kg. All patients were white. The completer analysis included 197 patients (85 tramadol, 112 placebo). Pain was significantly reduced in the tramadol LP group compared with the placebo group on day 7 (P = 0.002) and day 14 (P = 0.010). In the patient's assessment of global efficacy, 77.6% (66) of the tramadol LP group reported improvement by day 14, compared with 59.8% (67) of the placebo group; in the investigator's assessment, the efficacy of tramadol LP was rated very good or good for 612% (52) of patients, compared with 30.4% (34) for placebo. Improvement was reported before day 7 in 882% (75) of patients in the tramadol LP group, compared with 65.2% (73) in the placebo group (P = 0.021); the mean time from the initiation of treatment to reported improvement was 3 days for tramadol LP and 6 days for placebo (P < 0.001). Rates of response (defined as > or =30% pain reduction between days 0 and 14) were 64.7% (55) for tramadol LP and 50.0% (56) for placebo (P = 0.039); no rescue medication was used by 60.0% (51) of the tramadol LP group and 36.6% (41) of the placebo group (P - 0.001). One or more adverse event was reported by 45.0% (50) of the tramadol LP group, compared with 193% (23) of the placebo group (P < 0.001). As would be expected with an opiate agonist such as tramadol, the most common adverse events with this agent involved the gastrointestinal system (nausea, 22.5% [25] of patients; vomiting, 17.1% [19]) and the central nervous system (somnolence, 11.7% [13]).

CONCLUSIONS

In this study, tramadol LP 200 mg was significantly more effective than placebo in alleviating pain in patients with osteoarthritis of the hip or knee. It appeared to be relatively well tolerated for an opioid compound.