Translational biomarkers: from preclinical to clinical a report of 2009 AAPS/ACCP Biomarker Workshop

There have been some successes in qualifying biomarkers and applying them to drug development and clinical treatment of various diseases. A recent success is illustrated by a collaborative effort among the US Food and Drug Administration, the European Medicines Agency, and the pharmaceutical industry to provide a set of seven preclinical kidney toxicity biomarkers for drug development. Other successes include, but are not limited to, clinical biomarkers for cancer treatment and clinical management of heart transplant patients. The value of fully qualified surrogate endpoints in facilitating successful drug development is undisputed, especially for diseases in which the traditional clinical outcome can only be assessed in large, multi-year trials. Emerging biomarkers, including chemical genomic or imaging biomarkers, and measurement of circulating tumor cells hold great promise for early diagnosis of disease and as prognostic tests for managing treatment of chronic diseases such as osteoarthritis, Alzheimer disease, cardiovascular disease, and cancer. To advance the success of treating and managing these diseases, efforts are needed to establish the temporal relationship between changes in inflammatory or imaging biomarkers with the progression of the chronic disease, and in the case of cancer, between the extent of circulating cancer cells and tumor progression or remission.

Relative efficacy of drugs: an emerging issue between regulatory agencies and third-party payers

Drug regulatory agencies have traditionally assessed the quality, safety and efficacy of drugs, and the current paradigm dictates that a new drug should be licensed when the benefits outweigh the risks. By contrast, third-party payers base their reimbursement decisions predominantly on the health benefits of the drug relative to existing treatment options (termed relative efficacy; RE). Over the past decade, the role of payers has become more prominent, and time-to-market no longer means time-to-licensing but time-to-reimbursement. Companies now have to satisfy the sometimes divergent needs of both regulators and payers, and to address RE during the pre-marketing stages. This article describes the current political background to the RE debate and presents the scientific and methodological challenges as they relate to RE assessment. In addition, we explain the impact of RE on drug development, and speculate on future developments and actions that are likely to be required from key players.

Outcomes research collaborations between third-party payers, academia, and pharmaceutical manufacturers: What can we learn from clinical research?

Research collaborations between academic researchers, regulatory agencies, and pharmaceutical manufacturers have made the drug development process more efficient and have frequently supported the successful documentation of quality, safety, and efficacy of pharmaceuticals (the so-called three hurdles). Over recent years issues of drug cost, access, and utilization have moved to center stage, giving rise to a "fourth hurdle approval" process by third-party payers. This requires new forms of collaborative research among new players. This contribution highlights the need for a "triangular" relationship in the field of outcomes research between scientists in academia, third-party payer institutions, and pharmaceutical manufacturers. We discuss, and illustrate by case studies, how successful models of collaboration from the drug development process might be relevant to research activities related to the fourth hurdle. Case studies which may provide useful models for collaborative outcomes research include the "International Conference on Harmonization" process, the voluntary consultation procedures established by drug regulatory agencies, and the Quebec experience in database sharing.

Association between health-related quality of life and clinical efficacy endpoints in rheumatoid arthritis patients after four weeks treatment with anti-inflammatory agents

BACKGROUND

Improvement of health-related quality of life (QoL) is increasingly recognized as a maj or treatment goal for patients with rheumatoid arthritis (RA). There are several measures of general health status and of physical functioning for assessing treatment effects on QoL in patients with RA, however, the relationship between QoL outcomes and conventional clinical efficacy endpoints is not completely understood.

OBJECTIVE

To describe the association between changes in QoL and changes in other efficacy measures, among patients with RA after four weeks of treatment with etoricoxib, naproxen or placebo, and to explore differences in the association of changes in efficacy and changes in QoL parameters across treatment groups.

METHODS

The study used data from 1684 patients with RA enrolled in two identical clinical trials (one US and one multinational). Patients were randomized to placebo, etoricoxib 90 mg once daily, or naproxen 500 mg twice daily in a 2 : 2: 1 allocation ratio. Primary efficacy endpoints were tender joint count, swollen joint count, patient global assessment of disease activity (100 mm VAS), and investigator global assessment of disease activity (0 - 4 Likert scale). QoL assessments were based on the Health Assessment Questionnaire (HAQ) and the Medical Outcomes Survey Short Form 36 (SF-36). Mean differences between baseline and week four were calculated for each parameter studied. Linear regression analysis was performed to assess the association between changes in clinical efficacy and changes in QoL parameters, adjusted for covariates.

RESULTS

The degree of association between changes in tender or swollen joint counts and changes in QoL variables was low, explaining less than 10% of the variability for most QoL variables, except bodily pain (SF-36). In contrast, changes in patient global assessment of disease activity explained 33% of the variability in the overall HAQ score, and in the physical component score (SF-36; adjusted regression models). Values for investigator global assessment of disease activity were below those for patient global assessment but above joint count measures. Results were similar between the etoricoxib, naproxen and placebo groups in the degree of association between changes in efficacy and QoL variables.

CONCLUSION

Currently used efficacy endpoints are less than ideal predictors of change in QoL. There is no evidence from this study that the association between changes in CE endpoints and QoL was different across treatments. Our results highlight the need to assess both conventional efficacy measures and QoL in clinical trials of RA treatments.

Should 5-hydroxytryptamine-3 receptor antagonists be administered beyond 24 hours after chemotherapy to prevent delayed emesis? Systematic re-evaluation of clinical evidence and drug cost implications

PURPOSE

5-Hydroxytryptamine-3 receptor antagonists (5-HT(3) antagonists) are effective for preventing acute chemotherapy-induced emesis but the benefits of continuing administration of these agents beyond 24 hours after chemotherapy (delayed emesis) remain unclear. The purpose of this study was to provide estimates of clinical efficacy and drug acquisition cost associated with administering 5-HT(3) antagonists beyond 24 hours, as monotherapy or as added to dexamethasone.

METHODS

This analysis is based on the Cancer Care Ontario Practice Guidelines Initiative meta-analysis of the efficacy of 5-HT(3) antagonists. Results from the clinical trials covered in that meta-analysis were reanalyzed to provide estimates of absolute risk reductions (ARR) and numbers needed to treat (NNT) for 5-HT(3) antagonists, as monotherapy or as adjunct treatment. Numbers of 5-HT(3) antagonist unit doses per successfully treated patient were also calculated.

RESULTS

Five studies (comprising 1,716 assessable patients) compared a 5-HT(3) antagonist with placebo; five studies (2,240 patients) compared a combination of a 5-HT(3) antagonist and dexamethasone with dexamethasone monotherapy. ARR for monotherapy was only 8.2% (95% CI, 3.0% to 13.4%). On average, 74 5-HT(3) antagonist doses must be administered to 12 patients (NNT, 12.2; 95% CI, 7.5 to 33.4) not receiving dexamethasone to protect one patient from delayed emesis. In those patients receiving dexamethasone as standard antiemetic treatment in the delayed phase, the addition of a 5-HT(3) antagonist did not significantly improve control of delayed emesis as compared with dexamethasone monotherapy (ARR, 2.6%; 95% CI, -0.6% to 5.8%).

CONCLUSION

Neither clinical evidence nor considerations of cost effectiveness justify using 5-HT(3) antagonists beyond 24 hours after chemotherapy for prevention of delayed emesis.

Access of HTB, main metabolite of triflusal, to cerebrospinal fluid in healthy volunteers

OBJECTIVE

Triflusal has been shown to exert neuroprotective effects by downregulating molecules considered responsible for the development of Alzheimer's disease (AD). The aim of this study was to develop a population pharmacokinetic model to characterize plasma and cerebrospinal fluid (CSF) pharmacokinetics of the main active metabolite of triflusal-HTB (2-hydroxy-4-trifluoro-methylbenzoic acid)-in healthy volunteers.

METHODS

Data from two studies were combined. Study A: subjects received single oral doses of triflusal 900 mg. Triflusal and HTB plasma concentrations were extensively measured. Study B: triflusal 600 mg once daily was administered orally for 14 days. HTB plasma and CSF concentrations were determined in healthy volunteers. Population pharmacokinetic modeling was performed using NONMEM.

RESULTS

A one-compartmental model with rapid first-order absorption for triflusal and first-order formation of HTB best described plasma concentrations. Triflusal elimination rate constant was 50 times faster than that estimated for the metabolite. CSF concentrations of HTB ranged between 0.011 microg/ml and 0.341 microg/ml. A CSF-plasma partition coefficient of 0.002 and a k(e0) value of 0.059 h(-1) were estimated by means of population modeling.

CONCLUSION

In the present study in healthy volunteers, HTB penetrated into the CSF in a range of concentrations experimentally proven to have protective effects in AD. These concentrations suggest that triflusal could be used in the treatment of central nervous system diseases in doses similar to those used in cardiovascular diseases. Access to the CSF compartment was characterized by a slow equilibrium rate constant and a low CSF-plasma partition coefficient.

Rofecoxib attenuates both primary and secondary inflammatory hyperalgesia: a randomized, double blinded, placebo controlled crossover trial in the UV-B pain model

The analysis of drug's influence on peripheral and central sensitisation can give useful information about its mode of action and can lead to more efficacy in the treatment of pain. Peripheral inflammation is associated with peripheral expression and up-regulation of cyclooxygenase 2 (COX-2) in the CNS. The relative contribution of COX-2 mediated central sensitisation may be prominent under inflammatory conditions. In this randomized, double blinded, placebo controlled cross-over trial the effects of multidoses of the COX-2 selective inhibitor rofecoxib on primary and secondary hyperalgesia were evaluated in the UVB pain model. Twenty-four hours after local UVB irradiation at the upper leg of 42 healthy volunteers heat pain perception (HPPT) and heat pain tolerance thresholds (HPTT) were assessed within the inflammation. The area of secondary hyperalgesia was determined by pin prick test. Subjects received oral rofecoxib 50, 250, 500 mg or placebo. Pain testing was repeated after 3 and 6 h. Compared to placebo, rofecoxib significantly increased HPPT (1.55 and 1.08 degrees C, P<0.0001 and P=0.0333), HPTT (1.74 and 1.58 degrees C, P<0.0001 and P<0.0001), and reduced the mean area of secondary hyperalgesia by 15.6% (P=0.007) and 16.8% (P<0.001) after 3 and 6 h. No significant difference between the three dosage groups was observed. These data confirm peripheral effects of rofecoxib in a human inflammatory UV-B pain model and provide circumstantial evidence that even a standard clinical dose of rofecoxib reduces central hyperalgesia in inflammatory pain. We confirm that the effect of single oral dose of rofecoxib plateaus at 50 mg.

Effect of Information on Reported Adverse Events in a Placebo-Controlled Trial

OBJECTIVE

Although placebo controls are a standard measure in clinical trials the mechanisms underlying placebo effects are still not fully understood. We hypothesised that information about the likelihood of receiving placebo might influence the perception of adverse effects in volunteers participating in a clinical trial.

METHODS

Healthy subjects received either nifedipine 20 mg or placebo in an adaptive two-stage crossover study. Sixty subjects were randomised to a group given either correct (50% chance) or misleading (100% chance) information about the likelihood of receiving the active drug. A sum of the severity scores from visual analogue scales over all individual adverse effects was defined as the primary endpoint.

RESULTS

The analysis revealed no difference in the primary endpoint between the two groups. This lack of difference may in part be attributable to a conditioning effect as on the first study day higher symptom scores were reported by the participants than on the second study day. Furthermore, the day effect seemed to arise mainly when the first day treatment was the placebo. For the placebo the day effect was clearly significant (p = 0.012), with higher scores on the first day. A further explorative finding in patients given placebo was a tendency for higher scores in the group with the misleading information (p = 0.08). Nothing of that sort was found in the analysis for active treatment. The day effect collapsed and the factor information did not show any tendency of being a potential influence.

CONCLUSIONS

In the present study we did not find a statistically significant effect of misleading information on reported adverse events. The large treatment and day effects observed made it difficult to detect a potential small information effect. However, this study excluded a strong and relevant effect of information on the frequency and severity of reported adverse events.

Use of cost-effectiveness analysis in health-care resource allocation decision-making: how are cost-effectiveness thresholds expected to emerge?

BACKGROUND

An increasing number of health-care systems, both public and private, such as managed-care organizations, are adopting results from cost-effectiveness (CE) analysis as one of the measures to inform decisions on allocation of health-care resources. It is expected that thresholds for CE ratios may be established for the acceptance of reimbursement or formulary listing.

OBJECTIVE

This paper provides an overview of the development of and debate on CE thresholds, reviews threshold figures (i.e., cost per unit of health gain) currently proposed for or applied to resource-allocation decisions, and explores how thresholds may emerge.

DISCUSSION

At the time of this review, there is no evidence from the literature that any health-care system has yet implemented explicit CE ratio thresholds. The fact that some government agencies have utilized results from CE analysis in pricing/reimbursement decisions allows for retrospective analysis of the consistency of these decisions. As CE analysis becomes more widely utilized in assisting health-care decision-making, this may cause decision-makers to become increasingly consistent.

CONCLUSIONS

When CE analysis is conducted, well-established methodology should be used and transparency should be ensured. CE thresholds are expected to emerge in many countries, driven by the need for transparent and consistent decision-making. Future thresholds will likely be higher in most high-income countries than currently cited rules of thumb.

Asthma severity and medical resource utilisation

Asthma represents a growing public health problem and the cost of asthma has been rising in many countries. The aim of this study was to estimate the direct and indirect cost of asthma among adult patients in Italy, and to assess the relationship between healthcare resource use and asthma severity according to the Global Initiative for Asthma (GINA) classification system. A multicentre cross-sectional study was conducted in 16 Italian hospital-based specialised asthma clinics. Data collection was based on self-administered questionnaires and took place during the period May 1-November 30, 1999, and 500 consecutive patients with asthma, aged 18-55 yrs, were enrolled during regularly scheduled visits. Direct costs (drugs, physician visits, emergency service use and hospitalisation), indirect costs (loss of paid workdays) and total costs were determined in euros (Euros) for 1999. Patients with more severe disease, as classified by the GINA guideline, exhibited more night-time and daytime symptoms and were more limited in performing normal daily activities. The mean total cost of asthma per patient per year was estimated to be Euros 1,260; drug costs accounted for 16%, physician costs 12%, emergency service and hospitalisation costs 20% and indirect costs 52% of the mean cost. Stratified by severity, the total annual cost per patient amounted to Euros 720, Euros 1,046, Euros 1,535 and Euros 3,328 for patients with intermittent, mild persistent, moderate persistent and severe persistent asthma, respectively. Asthma severity, as determined by the Global Initiative for Asthma classification, is significantly associated with symptoms, limitations in normal daily activities, asthma-related medical resource utilisation and both direct and indirect costs. Asthma control is not only a clinical but also an economic imperative.

Clonidine added to bupivacaine enhances and prolongs analgesia after brachial plexus block via a local mechanism in healthy volunteers

BACKGROUND AND OBJECTIVE

The addition of clonidine to local anaesthetics enhances pain relief after peripheral nerve block, but the site of action is unproven.

METHODS

Seven healthy volunteers underwent three brachial block procedures using bupivacaine 0.25% 1 mg kg(-1) + epinephrine 1:200,000 (=local analgesic) in a randomized, double-blind cross-over fashion: (a) control treatment: local analgesic with 0.9% sodium chloride solution for the block and an intramuscular injection of saline; (b) intramuscular treatment: local analgesic with 0.9% NaCl for block and an intramuscular injection of clonidine 2 microg kg(-1) and (c) block treatment: local analgesic with clonidine 2 microg kg(-1) for block and an intramuscular injection of saline.

RESULTS

The onset and duration of complete blockade (sensory/motor/temperature) was evaluated in the four nerve regions of the hand and forearm. Additionally, sedation score, blood pressure, heart rate and plasma clonidine concentrations were determined. The median duration of complete sensory blockade was 270 min (range 0-600) for block treatment compared to 0 min (range 0-480) for intramuscular treatment (P < 0.05) and 0 min (range 0-180) for control treatment (P < 0.05). Motor and temperature blockade exhibited similar results. Administration of clonidine was associated with sedation and a decrease in heart rate and blood pressure independent of the route of administration. Plasma clonidine concentrations were lower for block compared to the intramuscular treatment.

CONCLUSIONS

The admixture of clonidine to bupivacaine plus epinephrine prolongs and enhances brachial plexus blockade. Lower clonidine plasma concentrations for block treatment strongly suggest a local effect.

Initiation of antihypertensive therapy among new users of cyclooxygenase-2-selective and nonselective NSAIDs

BACKGROUND

The comparative effects of cyclooxygenase-2- (COX-2) selective inhibitors and nonselective, nonsteroidal anti-inflammatory drugs (NSAIDs) on blood pressure are debated. Clinicians have been concerned about the need for antihypertensive treatment following therapy with these agents.

OBJECTIVE

To compare initiation of antihypertensive treatment among new users of the COX-2-selective inhibitor rofecoxib and of nonselective NSAIDs in clinical practice.

METHODS

Retrospective cohort study using the MediPlus (UK) database that covers 1.8 million patients throughout the UK. Patients included were at least 50 years of age, had at least 1 prescription for either diclofenac, ibuprofen, naproxen or rofecoxib (drugs of interest, DOIs), and had no prescription for any NSAID, COX-2 inhibitor, or antihypertensive treatment during the 6 months prior to their first/index prescription date. A subset of patients, classified as chronic and persistent new users, had at least 3 prescriptions of the index prescription DOI and did not switch to another DOI during the 6-month follow-up period. Logistic regression analysis, adjusted for potential predictors, was used to assess initiation of new antihypertensive treatment.

RESULTS

18,737 suitable patients were identified (diclofenac 7,861, ibuprofen 8,423, naproxen 1,556 and rofecoxib 897). Those using rofecoxib were older and more likely to be female than those using NSAIDs. During the 6 months following the index prescription, 7.0% of all new users and 11.5% of chronic and persistent new users initiated antihypertensive treatment. After adjusting for potential predictors there were no statistically significant differences in the risk of initiating antihypertensive treatment between new or chronic and persistent new users of rofecoxib, diclofenac, ibuprofen and naproxen (p > 0.05).

CONCLUSION

The results of this study did not indicate any significant differences in the initiation of antihypertensive therapy among patients who were prescribed rofecoxib and NSAIDs, even after multiple prescriptions.

A randomized, double-blind, placebo controlled study on analgesic effects of botulinum toxin A

OBJECTIVE

Botulinum toxin type A (BTXA) is used to treat neurologic disorders associated with increased muscle tone. Its use is often associated with pain relief.

METHODS

A possible direct analgesic effect of BTXA on C and Adelta fibers was studied on 16 healthy volunteers receiving 30 U BTXA into one forearm and pure saline into the other. To exclude the secondary effect due to muscular tone reduction, BTXA was injected intradermally. Thermal sensory testing of heat pain (threshold and tolerance) and neuroselective current sensory testing of current pain threshold/tolerance were performed at baseline and 3, 14, and 28 days after treatment. Thereafter, on day 28, capsaicin was administered simultaneously into both forearms to evaluate a possible peripheral effect and central effect on pain processing and on the axon reflex flare.

RESULTS

The authors observed no significant difference in any of the perception outcome measures between BTXA and placebo pretreated areas. Flare areas as a result of the release of neuropeptides after capsaicin application showed no differences.

CONCLUSIONS

The results suggest that pain reduction after BTXA treatment is mediated through its effect on muscle tone rather than a direct analgesic effect.

Ocular Blood Flow and Systemic Blood Pressure in Patients with Primary Open-Angle Glaucoma and Ocular Hypertension

PURPOSE

There is evidence that altered optic nerve head (ONH) blood flow may play a role in the development and progression of glaucoma. In the present study, the baseline characteristics were examined in a study population participating in a clinical trial in which the ocular hemodynamic effects of timolol and dorzolamide were compared.

METHODS

One hundred forty patients with primary open-angle glaucoma (POAG) or ocular hypertension (OHT) were included in this trial and their baseline parameters compared with those of a group of 102 age-matched control subjects. Scanning laser Doppler flowmetry was used to measure blood flow in the temporal neuroretinal rim and the cup of the ONH. Pulsatile choroidal blood flow was assessed by laser interferometric measurement of fundus pulsation amplitude. In addition, hemodynamic parameters and mean arterial pressure were calculated in both groups.

RESULTS

All ocular hemodynamic parameters were significantly lower in the POAG/OHT group compared with the healthy control group (P < 0.001 each). In addition, a significant positive correlation between laser Doppler flowmetry readings and mean arterial pressure was observed in patients with glaucoma but not in healthy control subjects. Likewise, the correlation coefficient between fundus pulsation amplitude and mean arterial pressure was higher in patients with glaucoma than in healthy control subjects.

CONCLUSIONS

The present study indicates reduced ONH and choroidal blood flow and an abnormal association between blood pressure and ocular perfusion in patients with primary open-angle glaucoma or ocular hypertension, independent of topical antiglaucoma medication. Hence, vascular dysregulation appears to be an early manifestation in glaucoma that is not caused by pharmacologic intervention.

A replicate study design for testing bioequivalence: a case study on two desmopressin nasal spray preparations

OBJECTIVE

The present study was carried out to test bioequivalence between two different desmopressin nasal spray preparations. Due to the high variability of plasma pharmacokinetics of intranasally administered peptides like desmopressin, appropriate study designs are required to assess bioequivalence. Therefore, a single-dose, replicate study design was used to evaluate bioequivalence of two desmopressin nasal sprays.

SUBJECTS AND METHODS

Thirty-two healthy male volunteers were enrolled in the study and were randomly assigned to receive the test- and reference drug on two occasions in a 4-period 2-sequence crossover study design. Subjects received a single dose of 20 microg (10 microg per nostril) of desmopressin-acetate per study day separated by wash-out periods of at least 1 week. Desmopressin blood concentrations were measured serially over a 14-h period using a validated radioimmunoassay method. Statistical analysis was initially performed using a complicated mixed-analysis model testing for individual bioequivalence according to recommendations by the Food and Drug Administration. This approach, however, failed to converge with all defined main PK parameters and, thus, a traditional mixed analysis of variance analysis based on population averages was definitely used for testing bioequivalence between study drugs. The procedure of selecting an appropriate statistical analysis for a replicate study design was predefined in the study protocol.

RESULTS

The 90% confidence intervals (CI) were calculated for the area under the time-concentration curve (AUC), maximum concentration (C(max)) and the time to reach C(max) (t(max)) of test/reference drug ratios for a bioequivalence range from 0.80-1.25. The mean test/reference drug ratios were completely within the 90% CIs with values of 1.041 (CI: 0.892-1.216), 1.021 (CI: 0.913-1.140) and 1.068 (CI: 0.914-1.249) for AUC(0-14 h), C(max) and t(max), respectively.

CONCLUSION

The rate and the extent of intranasal desmopressin absorption are identical for both study preparations. Thus, the desmopressin test preparation met all equivalence criteria and thereby was proven bioequivalent with a marketed reference nasal desmopressin spray.

Influence of tiapride on platelet counts in healthy volunteers and patients with movement disorders

BACKGROUND

The selective D2 antagonist tiapride is administered in various movement disorders. Furthermore, there are indications that tiapride increases platelet counts.

AIM

To characterize tiapride's potential to increase platelet counts in healthy subjects and patients with movement disorders.

METHODS

In Part A, 10 healthy volunteers received tiapride (300 mg/day) for 21 days in a longitudinal, prospective, open trial. One hundred healthy subjects served as controls. Part B was a retrospective analysis of 15 patients with movement disorders on tiapride [Huntington's disease (n=6), Morbus Little (n=3), hyperkinetic syndromes of undetermined etiology (n=3), blepharospasm (n=1), cervical dystonia (n=1), perioral dyskinesia (n=1)] and 15 age- and sex-matched controls.

RESULTS

Part A: Although serum prolactin levels increased by 526+/-14%, confirming good drug compliance, tiapride elicited only minor changes in platelet counts. Part B: Platelet counts correlated positively with the dose of tiapride (100-800 mg/day; r=.67; P=.007). Platelet counts were significantly higher in patients on tiapride compared to healthy age-matched controls (P<.001). Four patients responded to an increase in the tiapride dosage with an increase in platelet count by 97-173 cells/nl.

CONCLUSION

Three weeks of treatment with tiapride (300 mg/day) is insufficient to elevate platelet counts to a clinically relevant extent in young healthy volunteers. However, in elderly patients with movement disorders tiapride treatment is associated with markedly increased platelet counts.

Gastrointestinal transit and release of 5-aminosalicylic acid from 153Sm-labelled mesalazine pellets vs. tablets in male healthy volunteers

BACKGROUND

Mesalazine (5-aminosalicylic acid)-containing formulations, designed to optimize drug delivery to the ileo-caecal region, represent a cornerstone in the treatment of inflammatory bowel diseases.

AIM

: To test, by means of pharmaco-scintigraphy, whether novel mesalazine-containing pellets release 5-aminosalicylic acid in the same target region as mesalazine tablets (Salofalk).

METHODS

Fourteen healthy male volunteers received a single dose of either pellets or tablets containing 500 mg of mesalazine and 2 mg of 152Sm2O3 with a 1-week washout period. The gastrointestinal transit of 153Sm, incorporated into the formulations, was followed by gamma-scintigraphy. Mesalazine release was verified by assessing 5-aminosalicylic acid plasma pharmacokinetics.

RESULTS

The formulations reached the ileo-caecal target region almost at the same time (3.3 +/- 1 and 3.8 +/- 1 h for pellets and tablets, respectively). Plasma 5-aminosalicylic acid tmax values were comparable and corresponded to the time during which the formulations were located in the target region. Plasma AUC values were significantly lower for pellets, which might be explained by a more prolonged release of 5-aminosalicylic acid.

CONCLUSIONS

Novel mesalazine pellets and Salofalk tablets release active 5-aminosalicylic acid in the same target region and pass through the gastrointestinal tract under fasting conditions in healthy volunteers in a comparable time. From a comparison of in vitro dissolution and plasma concentration data, a slower and more prolonged release of 5-aminosalicylic acid from pellets is suggested.

Penetration of capecitabine and its metabolites into malignant and healthy tissues of patients with advanced breast cancer

Capecitabine is an oral prodrug of 5-fluorouracil (FU). Since FU concentrations achieved in malignant lesions are an important determinant of efficacy, we investigated the intratumoral transcapillary transfer of capecitabine and its metabolites in vivo. A total of 10 patients with skin metastases from breast cancer received a daily dose of 2500 mg m(-2) capecitabine administered orally in two divided doses for 2 weeks. Microdialysis probes were inserted into a cutaneous metastasis and subcutaneous connective tissue to evaluate the interstitial tissue pharmacokinetics of capecitabine and its metabolites 5'-deoxy-5-fluorocytidine (DFCR), 5'-deoxy-5-fluorouridine (DFUR), and FU by capillary electrophoresis. As intended with the prodrug design of capecitabine, FU was present in low concentrations in tumour interstitium (median c(max): 0.26 microg ml(-1)) when compared with capecitabine, DFCR, and DFUR (median c(max): 2.66, 4.22, and 2.13 microg ml(-1), respectively). Capecitabine and its metabolites easily penetrated malignant and healthy tissue and equilibrated within 45 min between plasma and tissue interstitium. Considering tissue exposure at the extracellular level, no significant differences between healthy and malignant tissues were observed. Our data show that absorption and metabolism determined the tissue pharmacokinetics of capecitabine. There was no evidence of drug tolerance, which may be attributed to impaired transcapillary transfer into tissue, even after repeated administration as shown for three patients.

Gastrointestinal transit and 5-ASA release from a new mesalazine extended-release formulation

BACKGROUND

Mesalazine (5-aminosalicylic acid, 5-ASA)-containing formulations represent a cornerstone in the treatment of inflammatory bowel diseases. Recently, a new formulation has been developed to provide selective and more homogeneous release of 5-ASA compared to traditional systems.

METHODS

In a first study, gastrointestinal transit was followed by gamma-scintigraphy after single-dose application of tablets containing 1200 mg mesalazine to 12 healthy male volunteers. 5-ASA release was verified by the assessment of plasma pharmacokinetics. In a second, 7-day, multiple-dose study, the steady state plasma pharmacokinetics, urinary excretion and safety profile were characterized after twice-daily tablet administration to 12 healthy volunteers.

RESULTS

Tablet erosion started after 6.9 +/- 1.1 h in the ascending or transverse colon. Radioactivity spread homogeneously throughout the colon, indicating the sustained release of active 5-ASA. Plasma kinetics indicated an earlier initial absorption of 5-ASA, i.e. during transit of the small intestine and ileum. Mean Cmax values (350.6 +/- 322.6 ng/mL) were observed during location in the ileo-caecal region. The mean relative absorption of 5-ASA was 19.9 +/- 18.2% in the small intestine and ileum and 80.1 +/- 18.2% in the colon.

CONCLUSIONS

The administration of the new mesalazine formulation was well tolerated, and 5-ASA was continuously released along the whole colon, a favourable prerequisite for the therapy of distally located inflammatory bowel disease.