The risk of congenital abnormalities in children fathered by men treated with azathioprine or mercaptopurine before conception

BACKGROUND

Immunosuppressive therapy with azathioprine and mercaptopurine is commonly used in patients with various chronic diseases. The few existing data on the reproductive safety of these drugs after paternal use before conception are inconclusive.

AIM

To examine the risk of congenital abnormalities in children fathered by men exposed to azathioprine or mercaptopurine before conception.

METHODS

This was a Danish population-based cohort study, based on data from the Prescription Database, the Medical Birth Registry and the Hospital Discharge Registry of North Jutland County, Denmark. Fifty-four exposed pregnancies, in which the father filed a prescription for azathioprine or mercaptopurine (between 1 January 1991 and 31 December 2001) before conception, were included. The controls comprised 57 195 pregnancies with no paternal azathioprine or mercaptopurine use.

RESULTS

Four children with congenital abnormalities (underlying paternal diseases: glomerulonephritis and severe skin disease) were found in 54 exposed pregnancies (7.4%), compared with 2334 (4.1%) in controls. The adjusted odds ratio for congenital abnormalities in children fathered by men treated with azathioprine or mercaptopurine was 1.8 (95% confidence interval, 0.7-5.0).

CONCLUSIONS

Our data may indicate that paternal use of azathioprine or mercaptopurine before conception is associated with an increased risk of congenital abnormalities. However, more data are needed to determine whether the association is causal.

Pharmacokinetics and pharmacodynamics of mivacurium in patients phenotypically heterozygous for the usual and atypical plasma cholinesterase variants (UA)

BACKGROUND

Mivacurium is hydrolyzed by plasma cholinesterase (pChe). The purpose of this study was to evaluate the pharmacodynamics and the pharmacokinetics of the three isomers of mivacurium in patients phenotypically heterozygous for the usual and the atypical pChe variant (UA).

METHODS

Thirty-two patients were included in a dose-response study, in which the patients received one of four doses of mivacurium. An additional bolus dose of mivacurium, to a total of 0.1 mg kg-1, was given followed by a continuous infusion adjusted to maintain 91-99% neuromuscular block. The times to different levels of recovery following the infusion were measured using mechanomyography and train-of-four (TOF) nerve stimulation. Twelve of the patients with an estimated duration of anaesthesia of more than 90 min were (randomly) selected for the pharmacokinetic part of the study. Venous samples were taken for determination of the three isomers of mivacurium. These results were compared with results from a previous study in phenotypically normal patients (UU).

RESULTS

The estimated ED50 and ED95 were 24 and 69 microg kg-1, respectively. The median (range) infusion rate was 3.7 microg kg-1 min-1 (1.2-2.9) and the time to a TOF ratio of 0.7 was 29.8 min (16.1-44.8). The median clearances of the cis-cis, cis-trans and trans-trans isomers were 3.7, 29 and 28 ml kg-1 min-1, respectively. The elimination half-lives of the isomers were 45, 6.7 and 6.3 min, respectively.

CONCLUSION

In patients heterozygous for the usual and the atypical variant (UA), the potency of mivacurium is higher, the infusion requirements lower and the rate of spontaneous recovery prolonged, compared with phenotypically normal patients. The clearances of the active isomers are significantly lower and the elimination half-lives longer in heterozygous patients than in phenotypically normal patients (UU). The pharmacokinetics of the inactive cis-cis isomer was not affected.

Pharmacological monitoring of azathioprine therapy

BACKGROUND

Studies on azathioprine (Aza) treatment in Crohn disease have indicated a positive correlation between clinical remission and a concentration in erythrocytes of the metabolites 6-thioguanine nucleotides (E-6-TGN) above 230 pmol/8 x 10(8) RBC. A concentration of the methylated Aza metabolites (E-6-MMP) above 5000 pmol/8 x 10(8) RBC has been correlated to hepatotoxicity. Thiopurine methyltransferase (TPMT) is responsible for the formation of methylated metabolites and lower E-TGN levels, and TPMT genotyping has been proposed as guidance for dosage. In a cross-sectional study we investigated relationships between the clinical outcome and Aza dose, the TPMT genotype and the Aza metabolite levels among patients with Crohn disease.

METHODS

TPMT genotype (PCR assay), azathioprine metabolite levels (HPLC analysis) and xanthine oxidase (XO) activity were determined once in 71 randomly selected Crohn patients on an unaltered Aza dose for at least 3 months.

RESULTS

None of the doses of Aza, TPMT genotype, E-6-TGN-, E-6-MMP levels or XO activity were significantly related to disease activity (H-B score), (P = 0.18, P = 0.69, P = 0.90, P = 0.54, P = 0.29, respectively). Leucopenia and/or hepatotoxicity were not demonstrated in any patient. Four patients had a heterozygous TPMT genotype (6.1%; 95% CI: 1.68%-14.80%). The 4 TPMT heterozygous patients had higher E-6-TGN levels than did the 67 remaining patients (P = 0.008).

CONCLUSIONS

To explore the applicability of TPMT genotyping, E-6-TGN and E-6-MMP levels for therapeutic drug monitoring, large prospective studies with patient entry at the start of Aza therapy are needed. Until the results of such studies are available, the dose adjustments of Aza should be guided primarily by clinical response and blood counts; metabolite level measurements can only be applied to identify therapeutic non-compliance.

Azathioprine, mercaptopurine and birth outcome: a population-based cohort study

BACKGROUND

Data on the safety of azathioprine and mercaptopurine during pregnancy are very sparse.

AIM

To examine the risk of adverse birth outcomes in women who took up prescriptions for azathioprine or mercaptopurine during pregnancy.

METHODS

This is a Danish cohort study based on data from a population-based prescription registry, the Danish Birth Registry and the Hospital Discharge Registry. To examine the risk of congenital malformations, we included nine pregnancies exposed 30 days before conception or during the first trimester. To examine perinatal mortality, pre-term birth and low birth weight, we included 10 pregnancies exposed during the entire pregnancy. Eleven different exposed women were included in the study. Outcomes were compared with those of 19 418 pregnancies in which no drugs were prescribed to the mothers.

RESULTS

Fifty-five per cent of the exposed women had inflammatory bowel disease and 45% other diseases. Adjusted odds ratios for congenital malformations, perinatal mortality, pre-term birth and low birth weight were 6.7 (95% confidence interval, 1.4-32.4), 20.0 (2.5-161.4), 6.6 (1.7-25.9) and 3.8 (0.4-33.3), respectively.

CONCLUSIONS

Our results suggest that there is an increased risk of congenital malformations, perinatal mortality and pre-term birth in children born to women treated with azathioprine or mercaptopurine during pregnancy. More data are needed to determine whether the associations are causal or occur through confounding.

Analgesic effect of i.v. paracetamol: possible ceiling effect of paracetamol in postoperative pain

BACKGROUND

Despite the widespread use of paracetamol for many years, the analgesic serum concentrations of paracetamol are unknown. Therefore the correlation between serum paracetamol concentrations and the analgesic effect was studied.

METHODS

Sixty-four women undergoing laparoscopic sterilization were included in a double-blind, placebo-controlled, randomized study. Patients were given i.v. propacetamol 40 mg kg(-1) (group H), 20 mg kg(-1) (group I), 10 mg kg(-1) (group L) or placebo after surgery. Alfentanil was available via patient-controlled analgesia (PCA) during the 4-h postoperative study period. The patients' self-reported pain was registered on the visual analog scale (VAS). A pharmacokinetic model was fitted to the paracetamol data.

RESULTS

One to 3 h after injection of propacetamol the alfentanil consumption was significantly (P = 0.01-0.04) higher in the placebo group compared with groups H, I, and L receiving propacetamol. There were no significant differences between the amounts of alfentanil consumed in groups H, I, and L. Initial VAS-scores were moderate (5.4-6.2), and declined significantly (P < 0.0001) over time, with no difference between groups. Paracetamol followed an open two-compartment model with i.v. administration and first order elimination. The estimated concentrations immediately (t = 0) after injection were 56 mg l(-1) (H), 28 mg l(-1) (I) and 14 mg l(-1) (L).

CONCLUSION

We showed a significant opioid-sparing effect of paracetamol in the immediate postoperative period. Pharmacokinetic data were in accordance with other studies. Our results suggest that a ceiling effect of paracetamol may be present at i.v. doses of 5 mg kg(-1), i.e. a serum concentration of 14 mg l(-1), which is a lower dose than previously suggested.

The pharmacodynamics and pharmacokinetics of mivacurium in children

BACKGROUND

In children, onset time and duration of action of mivacurium are shorter than in adults. Some suggest that this is due to differences in plasma cholinesterase (pChe), whereas others indicate that there is no difference. The purpose of this study was to evaluate the pharmacodynamics and pharmacokinetics of mivacurium in phenotypically normal children aged 3-6 and 10-14 years old, respectively.

METHODS

Ten children aged 3-6 years and 10 children aged 10-14 years were studied during halothane anaesthesia. Before induction of anaesthesia, a blood sample was drawn to measure the pChe activity and phenotype. The neuromuscular block was monitored at the thumb using train-of-four (TOF) nerve stimulation every 12 s and mechanomyography. The times to different levels of neuromuscular recovery following mivacurium 0.2 mg/kg were recorded. The concentrations in venous blood of the three isomers and the metabolites of mivacurium were measured.

RESULTS

No statistically significant difference was found in pChe activity or in the pharmacodynamics of mivacurium. The onset time was 1.4 min (0.8-1.9) median (range) and 1.3 min (1.1-1.9) and the time to first response to TOF nerve stimulation was 9.6 min (6.5-12.6) and 10.5 min (7.0-14.0) in young and older children, respectively. The pharmacokinetic data were too sparse to allow analysis of the two age groups separately (8 and 8 patients), hence the data were pooled. The median clearances of the cis-cis, the cis-trans, and the trans-trans isomer were 5.5, 51.0 and 30.5 ml/kg/min, respectively.

CONCLUSION

Our data indicate that there are no major differences in pharmacodynamics or pharmacokinetics of mivacurium between young (3-6 years) and older (10-14 years) children.

Pharmacokinetic studies of neuromuscular blocking agents: good clinical research practice (GCRP)

In September 1997, an international consensus conference on standardization of studies of neuromuscular blocking agents was held in Copenhagen, Denmark. Based on the conference, a set of guidelines for good clinical research practice (GCRP) in pharmacokinetic studies of neuromuscular blocking agents is presented. Guidelines include: design of the study; relevant patient groups to investigate; test drug administration, sampling and analysis; pharmacokinetic analysis; pharmacokinetic/pharmacodynamic modeling; population pharmacokinetics; statistics; and presentation of pharmacokinetic data. The guidelines are intended to aid those working in this research area; it is hoped that they will assist researchers, editors of scientific papers, and pharmaceutical companies in improving the quality of pharmacokinetic studies.

Pharmacokinetics of rectal paracetamol after repeated dosing in children

Twenty-three children (aged between 9 weeks and 11 yr) were given paracetamol suppositories 25 mg kg-1 every 6 h (maximum 5 days) after major surgery and serum and saliva concentrations were measured. There was a good correlation (r = 0.91, P < 0.05) between saliva and serum concentrations. A one-compartment linear model with first-order elimination and absorption and lag-time was fitted to the data (ADAPT II). At steady state, the mean (SD) concentration was 15.2 (6.8) mg litre-1. Mean (SD) time to reach 90% of the steady state concentration was 11.4 (8.6) h. Body weight, age and body surface area were well correlated (P < 0.05) with clearance and apparent volume of distribution. There was no evidence of accumulation leading to supratherapeutic concentrations during this dosing schedule for a mean of approximately 2-3 days.

The influence of drug-induced low plasma cholinesterase activity on the pharmacokinetics and pharmacodynamics of mivacurium

BACKGROUND

The short duration of action of mivacurium results from its rapid hydrolysis by plasma cholinesterase. Bambuterol, an oral bronchodilator, has an inhibiting effect on plasma cholinesterase. The purpose of this study was to evaluate the effect of bambuterol-induced low plasma cholinesterase activity on the pharmacokinetics and pharmacodynamics of mivacurium.

METHODS

Fourteen patients received 20 mg bambuterol and 14 patients received placebo orally 2 h before induction of anesthesia. During anesthesia the neuromuscular block was monitored at the thumb using train-of-four nerve stimulation every 12 s and mechanomyography. The times to different levels of neuromuscular recovery after 0.2 mg/kg mivacurium were measured. The concentrations in venous blood of the three isomers and the metabolites of mivacurium were measured using high-performance liquid chromatography.

RESULTS

Plasma cholinesterase activity was inhibited a median of 90% (range, 67-97%) after bambuterol. The time to first response to train-of-four nerve stimulation was 15 min (range, 9-21 min) and 59 min (range, 32-179 min) in patients receiving placebo and bambuterol, respectively. The estimated clearances of the isomers were significantly lower and the elimination half-lives of all three isomers significantly prolonged in patients receiving bambuterol. No difference was seen in elimination half-lives of the metabolites. The elimination rate constant from the effect compartment and the potency of mivacurium was not affected by bambuterol.

CONCLUSION

A 90% inhibition of plasma cholinesterase activity significantly reduced clearance of the isomers of mivacurium. Correspondingly, the duration of action of 0.2 mg/kg mivacurium was prolonged three- to fourfold, compared with patients not administered bambuterol.

[Eosinophilic enteritis]

We present a case of eosinophilic enteritis in a 45 year-old male with clinical and radiological signs of stenotic inflammatory ileal disease. A diagnosis of Crohn's disease was considered. He developed small bowel obstruction and sixty cm of obstructed ileum was resected. Histopathological examination revealed the diagnosis of eosinophilic enteritis primarily localized to the tunica muscularis. One year postoperatively he relapsed and small bowel X-ray demonstrated 1 m narrow and irregular ileum. He was treated with mesalamine, azathioprine, and cromoglicate, went into remission and fares well one and a half years later.

Development of a long-term ascending urinary tract infection mouse model for antibiotic treatment studies

A model of ascending unobstructed urinary tract infection (UTI) in mice was developed to study the significance of the antibiotic concentration in urine, serum, and kidney tissue for efficacy of treatment of UTI in general and pyelonephritis in particular. Outbred Ssc-CF1 female mice were used throughout the study, and Escherichia coli was used as the pathogen. The virulence of 11 uropathogenic E. coli isolates and 1 nonpathogenic laboratory E. coli strain was examined. Strain C175-94 achieved the highest counts in the kidneys, and this strain was subsequently used as the infecting organism. The model gave reproducible bladder infections, i.e., bacteria were recovered from 22 of 23 control mice after 3 days, and histological examination of kidney tissue showed that of 14 infected kidneys, 7 (50%) showed major histological changes, whereas 3 of 36 uninfected kidneys showed major histological changes (P = 0.018). Once the model was established, the efficacies of different doses of cefuroxime and gentamicin, corresponding to active concentrations in urine only or in urine, serum, and kidney tissue simultaneously, were examined. All cefuroxime doses resulted in significantly lower counts in urine than control treatments, but the dose which produced concentrations of cefuroxime only in urine and not in serum or kidney tissue had no effect on kidney infection. Even low doses of gentamicin (0.05 mg/mouse) resulted in concentrations in renal tissue for prolonged times due to accumulation. All gentamicin doses had a significant effect (compared to the effect of the control treatment) on bacterial counts in urine and kidneys. The antibiotic effect on bacterial counts in bladders was negligible for unknown reasons. Use of the mouse UTI model is feasible for study of the effect of an antibiotic in the urinary system, although the missing antibacterial effect in the bladder needs further evaluation.

Plasma paracetamol concentrations and pharmacokinetics following rectal administration in neonates and young infants

BACKGROUND

Despite widespread use in children pharmacokinetic data about paracetamol are relatively scarce, not the least in the youngest age groups. This study aimed to describe plasma paracetamol concentrations and pharmacokinetics of a single rectal paracetamol dose in neonates and young infants.

METHODS

Perioperatively, 17 neonates and infants < or =160 days of age received one rectal paracetamol dose (mean 23.9 mg/kg (+/-4.2 mg/kg)). Blood samples were drawn at 60, 120, 180, 240, 300 and 360 min, according to the infants' weights. Plasma paracetamol concentrations were measured by a Colorometric Assay, Ectachem Clinical Chemistry Slides (Johnson & Johnson Clinical Diagsnostics).

RESULTS

The plasma paracetamol concentrations were mainly below the therapeutic (i.e. antipyretic) range of 66-132 micromol/l and did not exceed 160 micromol/l in any infant. The mean maximum plasma concentration (Cmax) was 72.4 micromol/l (+/-33.5 micromol/l) and the time to Cmax, i.e. the mean Tmax was 102.4 min (_+59.1 min). The mean "apparent" terminal half-life (n=10) was 243.6 min (+/-114.1 min).

CONCLUSION

The absorption of rectal paracetamol (mean dose 23.9 mg/kg, +/-4.2mg/kg) in young infants <160 days is variable and often prolonged and achieves mainly subtherapeutic plasma concentrations.

Absorption and retention of nickel from drinking water in relation to food intake and nickel sensitivity

Two studies were performed to examine the influence of fasting and food intake on the absorption and retention of nickel added to drinking water and to determine if nickel sensitization played any role in this regard. First, eight nonallergic male volunteers fasted overnight before being given nickel in drinking water (12 micrograms Ni/kg) and, at different time intervals, standardized 1400-kJ portions of scrambled eggs. When nickel was ingested in water 30 min or 1 h prior to the meal, peak nickel concentrations in serum occurred 1 h after the water intake, and the peak was 13-fold higher than the one seen 1 h after simultaneous intake of nickel-containing water and scrambled eggs. In the latter case, a smaller, delayed peak occurred 3 h after the meal. Median urinary nickel excretion half-times varied between 19.9 and 26.7 h. Within 3 days, the amount of nickel excreted corresponded to 2.5% of the nickel ingested when it was mixed into the scrambled eggs. Increasing amounts were excreted as the interval between the water and the meal increased, with 25.8% of the administered dose being excreted when the eggs were served 4 h prior to the nickel-containing drinking water. In the second experiment, a stable nickel isotope, 61Ni, was given in drinking water to 20 nickel-sensitized women and 20 age-matched controls, both groups having vesicular hand eczema of the pompholyx type. Nine of 20 nickel allergic eczema patients experienced aggravation of hand eczema after nickel administration, and three also developed a maculopapular exanthema. No exacerbation was seen in the control group. The course of nickel absorption and excretion in the allergic groups did not differ and was similar to the pattern seen in the first study, although the absorption in the women was less. A sex-related difference in gastric emptying rates may play a role. Thus, food intake and gastric emptying are of substantial significance for the bioavailability of nickel from aqueous solutions.

Pregnancy outcome for women with Crohn's disease: a follow-up study based on linkage between national registries

OBJECTIVE

Crohn's disease, characterized by chronic intestinal inflammation, is sometimes followed by malabsorption, which may interfere with embryogenesis and fetal growth. Therefore we examined birthweight, the frequency of preterm birth, and other reproductive outcomes in the offspring of women with Crohn's disease.

METHODS

We used a historical registry-based study, with linkage between the Danish National Registry of Patients and the Danish Medical Birth Registry. Included were 510 newborns to mothers with Crohn's disease and 3018 controls in the study period from 1982 to 1992.

RESULTS

The average birthweight of newborns to mothers with Crohn's disease was 185 g, 134 g less than expected for primiparas and multiparas. After adjusting for potential confounders the differences were 142 g (95% confidence interval [CI95%] = 76, 208) and 105 g (CI95% = 37, 173), respectively. The risk of low birthweight was increased in Crohn patients (odds ratio [OR] = 2.4; CI95% = 1.6-3.7), as was the risk of preterm birth (OR = 1.6; CI95% = 1.1-2.3).

CONCLUSION

We found a lower birthweight in newborns of patients with Crohn's disease, indicating that Crohn's disease or its treatment may influence fetal growth.

Hepatobiliary dysfunction and primary sclerosing cholangitis in patients with Crohn's disease

BACKGROUND

Only a few studies have attempted to determined the prevalence of long-standing abnormal liver function and primary sclerosing cholangitis (PSC) in patients with Crohn's disease (CD). The aim of the study was to determine the prevalence of long-standing abnormal liver function test results and to describe the clinical, biochemical, and histologic findings in patients with large-duct classic PSC and small-duct PSC (that is, normal cholangiogram) in patients with CD during a 15-year period.

METHODS

Patients with CD and long-standing abnormal liver function results were investigated individually with endoscopic retrograde cholangiography and liver biopsy.

RESULTS

Of 262 consecutive patients with CD, 38 (15%) had long-standing increased alkaline phosphatase (ALP) values (mean, 1065 U/l; range, 321-4165 U/l). Of these, 10 patients were classified as having hepatic disease (4%), of which 9 had PSC and 1 had a non-specific reactive hepatitis. Of nine patients with PSC (3.4%), three were classified as having large-duct PSC; five, small-duct PSC; and one, unclassified. In patients with large-bowel CD (n = 102) the prevalence of PSC was 9%. Mean age at diagnosis of PSC was 35 years (22-46 years), and the female to male ratio, 7:2. All PSC patients had large-bowel involvement (P < 0.00015), and two of them developed colonic carcinoma of the large bowel (P < 0.01). All cases of small-duct PSC were stage 1, whereas large-duct PSC were stage 2-3. During the observation period (mean, 5.4 years) no PSC patients died.

CONCLUSIONS

The results of our study indicate that PSC is the major hepatic disease in patients with CD and long-standing abnormal liver function tests and is approximately as prevalent as in ulcerative colitis. Patients with PSC and CD may have a milder liver disease than patients with PSC and ulcerative colitis, perhaps because large-duct PSC is less common in patients with CD. Cholangiograms and liver biopsies are both needed to evaluate the extent of the disease.

Stereoselective pharmacokinetics of methadone in chronic pain patients

Ten patients with chronic pain were randomized to an open, balanced, crossover study. Each patients received two different preparations of racemic methadone, i.e., tablets and intravenous infusion. The pharmacokinetic parameters of the R- and S-enantiomers of the racemate are reported. The analgesically active R-methadone has a significantly longer mean elimination half-life than the optical antipode S-methadone (t1/2 = 37.5 and 28.6 h, respectively). The mean total volume of distribution is 496.6 L for R-methadone and 289.1 L for S-methadone. Significant differences in the mean clearance between R- and S-methadone are seen (0.158 and 0.129 L/min, respectively). However, the lagtime after oral administration and the bioavailability did not show differences between the isomers. The data suggest that both enantiomers of methadone should be measured if correlations between pharmacodynamics and kinetics are made due to the stereoselective differences in half-life, total volume of distribution, and clearance.

Assessment of the diagnoses of Crohn's disease and ulcerative colitis in a Danish hospital information system

BACKGROUND

Our aim was to estimate the completeness-that is, whether all patients were included in the system-and the validity-that is, whether the diagnostic criteria were fulfilled for the patients registered-of the diagnoses of Crohn's disease and ulcerative colitis in a Danish hospital system.

METHODS

Information in a regional hospital system, in the County of North Jutland, Denmark, was compared with hospital records and information in a pathology system.

RESULTS

The analysis of the completeness included 143 patients with Crohn's disease and 285 patients with ulcerative colitis. The completeness of the regional hospital system using the pathology system as a reference standard was 94% for both diseases. The analysis of the validity included 281 patients registered as having Crohn's disease and 506 patients registered as having ulcerative colitis. The validity of the two diagnoses was 97% and 90%, respectively.

CONCLUSIONS

The regional hospital system showed few misclassifications of the diagnoses of Crohn's disease and ulcerative colitis. Thus the nationwide hospital system (based on the regional hospital systems) may provide a unique study base for future research.

Clinical pharmacology in gastroenterology: development of new forms of treatment of inflammatory bowel disease

Kinetic-dynamic aspects of the development of slow-release mesalazine, Pentasa (now an established treatment of inflammatory bowel disease (IBD)), and cyclosporin, a T cell selective immunosuppressant (still in the investigative phase), are reviewed as examples of Danish contributions at an early stage to international, clinical drug research. Apart from increasing the therapeutic options for patients with IBD, current and future studies with these (and other) drugs may add important clues to a more precise understanding of the basic pathogenetic mechanisms (e.g. cytokines, adhesion molecules) involved in these diseases. The future development and clinical implementation of novel drug designs in IBD and other gastrointestinal diseases may be expected to benefit from a continued or even closer collaboration between clinical gastroenterologists and basic research institutions, including the pharmaceutical industry at an early stage.

Bioavailability of controlled release mesalazine (5-ASA) preparations

Salazosulfapyridine was generated by Nanna Svartz in 1941. Mesalazine (5-ASA) was demonstrated in 1977 to be the therapeutically active moiety of salazosulfapyridine. Since then, a number of alternatives to salazosulfapyridine have appeared: olsalazine and salicylazobensoic acid, which are as salazosulfapyridine azo-preparations. Also, pure mesalazine drugs have been developed: Asacol, Claversal, and Pentasa. Despite the many similarities of these pure mesalazine controlled-release drugs, there are also significant differences. Some of these are due to different pharmaceutical designs of the delivery principle. Other important parameters are gastrointestinal pH variations in the healthy and diseased gut, and variations in ventricular emptying and in intestinal transit patterns.

Assay of tocainide enantiomers in plasma by solid-phase extraction and indirect chiral high-performance liquid chromatography after derivatization with (-)-menthyl chloroformate

A fast high-performance liquid chromatographic (HPLC) assay was developed for determination of tocainide enantiomers in plasma. Subsequent to solid-phase extraction of tocainide from plasma, homochiral derivatization with (-)-menthyl chloroformate enabled separation of the enantiomers by a conventional reversed-phase HPLC system. The detection was performed by UV absorption at 262 nm. An enantiomeric resolution of 1.0 was obtained. Linearity of the method was investigated and found to be good in the range from 1.0 to 20.0 micrograms/ml tocainide enantiomer and the limit of quantitation was 1.0 microgram/ml. The method was applied to a study of the distribution and elimination pharmacokinetics of tocainide enantiomers in the rabbit. No difference in distribution or elimination between the enantiomers was found nor did the enantiomers affect the disposition of one another when administered together as the racemate.

Dicloxacillin and flucloxacillin: pharmacokinetics, protein binding and serum bactericidal titers in healthy subjects after oral administration

The pharmacokinetics of dicloxacillin and flucloxacillin were studied in 12 healthy volunteers after oral administration. The participants received a single dose of either dicloxacillin (0.5 g, 0.75 g or 1.0 g) or flucloxacillin (0.75 g) in a cross-over fashion. Antibiotic concentrations were determined in serum and urine by bioassay and followed for 8 and 24 h, respectively. The three dicloxacillin dosages showed no significant differences for the serum elimination half-lives (t1/2 beta, median: 72 min). Comparing 0.75 g flucloxacillin with the same dose of dicloxacillin, no significant differences between the values of Cmax, t1/2 beta and AUC were found. Protein binding as determined by ultrafiltration in pooled serum was 94.7-96.2% for flucloxacillin and 96.4-97.2% for dicloxacillin. The serum bactericidal titers were similar for the two drugs. In conclusion, dicloxacillin and flucloxacillin showed similar pharmacokinetic behavior after 0.75 g doses in human volunteers.

Myocardial uptake kinetics of tocainide enantiomers in the isolated perfused rabbit heart

The extent of myocardial accumulation of tocainide, administered as single enantiomers and as well as racemate, was determined in the isolated, spontaneous beating rabbit heart. The heart was retrogradely perfused at a constant rate and fractions of the perfusate were collected during and after infusion. Kinetic parameters for myocardial accumulation and disposition of tocainide were indirectly determined from drug concentration/time course in the outflow perfusate. No stereoselectivity in myocardial accumulation was observed. A two compartment model with mean half-lives for distribution and elimination of 0.60 and 3.78 min, respectively, was fitted to the accumulation and disposition data. At steady-state, tocainide enantiomers were accumulated about three times in the myocardium relative to the perfusion liquid.

Antibiotic activity in serum following single and repeated oral administration of sodium fusidate in volunteers

The pharmacokinetics of antibiotic activity were investigated in 10 healthy, female volunteers receiving a single oral dose of sodium fusidate (500 mg) followed after 48 h by repeated oral dosing of 250 mg b.i.d. for 5 consecutive days. By use of turbidimetry, drug-related antibiotic activity in serum was determined and expressed as fusidic acid equivalents. After a single dose and repeated dosing, the peak concentrations were (mean +/- SE): 30 +/- 3 micrograms/ml and 27 +/- 3 micrograms/ml, respectively (NS), and the trough concentration at steady state was 8.4 +/- 1.8 micrograms/ml. The experimental and predicted accumulation ratios were 2.1 +/- 0.1 versus 1.6 +/- 0.2, respectively (P < 0.16). By use of a model independent method, the terminal elimination half-lives were estimated to be 11 +/- 1 h and 13 +/- 2 h after a single dose and repeated doses, respectively (NS). The total clearances of antibiotic activity were 2.0 +/- 0.4 l/h after a single dose and 1.6 +/- 0.2 l/h after repeated doses (P < 0.11). Model dependent pharmacokinetic parameters were also obtained by fitting a two-compartment open model to the median serum concentrations which, with respect to half-life and clearance, gave values close to those observed by use of the model independent approach. Safety-wise, biochemical parameters were within the normal range. However, a statistically significant increase in ASAT and a decrease in leucocytes were observed. The tolerability of the drug was good and only minor adverse events were reported.

Pharmacokinetics of tinzaparin (Logiparin)--a low molecular weight heparin--after single and repeated intravenous administration in rats

After a single and repeated i.v. injections of 1 mg/kg 3H-radiolabelled tinzaparin once daily to rats for 7, 14, and 21 days, drug-related radioactivity in plasma, tissues, urine and faeces was measured by use of liquid scintillation counting. The decay in plasma could be described by a three-compartment model with half-lives of the two distributive phases and the terminal elimination phase of 15 min, 90 min, and 37 hrs, respectively. The peak plasma concentration did not change during repeated dosing, as opposed to the trough concentration which increased 3 fold. The decay in tissues was significantly different from that in plasma, and showed less fluctuations. Drug-related radioactivity accumulated gradually with repeated dosing, reaching accumulation ratios between 5 and 9, when based on trough concentrations. Slow elimination was observed from tissues, and significant amounts were still present 14 days after discontinuation of the repeated dosing. In the liver, the concentrations were almost constant during a dosing interval. After a single injection, 86% and 4% of the administered radioactive dose were excreted in urine and faeces over 7 days, respectively, the majority being recovered during the first 24 hrs, demonstrating that the major route of elimination was by renal excretion. The molecular mass distribution of radioactivity in urine was similar but not identical to the injected test substance. It was shifted slightly towards lower molecular mass and had no anti-factor Xa activity, suggesting that the heparin was either inactivated, presumably by desulphation, or that the antithrombin binding portion of the drug was cleared through a different route.

Effect of olsalazine and mesalazine on intraluminal pH of the duodenum and proximal jejunum in healthy humans

BACKGROUND

Treatment of inflammatory bowel disease with olsalazine causes diarrhoea in 10% of patients. This is claimed to be caused by a drug effect on mucosal transport in the small intestine, which might be reflected in the intraluminal pH. We aimed to study the effect on jejunal pH of olsalazine (Dipentum) and an alternative preparation, slow-release mesalazine (Pentasa).

METHODS

Thirteen healthy volunteers, seven male and six female, participated in a randomized, crossover study. Steady-state conditions were obtained after ingestion of 2 g or 6 g mesalazine daily or 2 g olsalazine daily for 1 week. The pH of the duodenum and proximal jejunum was measured by using pH-sensitive, radiotransmitting capsules, the location of which was confirmed by fluoroscopy.

RESULTS

No effect of either drug on duodenal pH was detected. Mean duodenal pH ranged from 6.18 to 6.22. The mean pH of the pre-medication proximal jejunum was 6.02. Mesalazine had no significant effect, but olsalazine significantly increased the pH of the proximal jejunum (mean pH, 6.47).

CONCLUSIONS

Our results indicate that the effect of olsalazine on jejunal transport of electrolytes and water, observed in experimental studies, also applies to human subjects in steady-state conditions, and adaptation does not occur within 6 days.

Pharmacokinetics of 1 alpha-hydroxycholecalciferol after intraperitoneal, intravenous and oral administration in patients undergoing peritoneal dialysis

Intravenous (i.v.) injection of vitamin D3 has a well known suppressive effect on the release of parathyroid hormone. However, the i.v. route is inconvenient in patients undergoing peritoneal dialysis. Moreover, no study has been published on the pharmacokinetics of 1 alpha-hydroxycholecalciferol (1 alpha-OHD3) after intraperitoneal (IP), i.v. and oral administration. Therefore, the appearance of 1,25-(OH)2D3 after administration of 1 alpha-OHD3 was studied in 8 peritoneal dialysis patients. Open, prospective, randomized cross-over design with single doses of 1 alpha-OHD3 (80 ng/kg BW) given on 3 separate occasions either IP, i.v. or oral was applied. After the administration of 1 alpha-OHD3, blood was collected at baseline and 0.5, 1, 2, 3, 4, 6, 12 and 24 h for measurement of circulating 1,25-(OH)2D3. A one compartment model with first order absorption and elimination (Cpl = Be-ke*t-Ae-ka*t) was fitted to the concentrations following i.v. administration. Following IP and oral administration the concentrations did not reach maximum levels within the time of blood sampling. In all cases, the 24 h area under the time/concentration curve for 1,25-(OH)2D3 (AUC24) was calculated using the trapezoidal method. Residual areas were calculated using the terminal slope from i.v. administration, and added to AUC24 giving AUC0-->infinity. After i.v. administration A, ka, B, ke, t1/2, AUC24 and AUC0-->infinity were (mean +/- SD) 62.9 +/- 16.4 pg/ml, 0.76 +/- 0.30 h-1, 71.6 +/- 14.7 pg/ml, 0.017 +/- 0.015 h-1, 109.4 +/- 129.5 h, 1315.8 +/- 236.9 pg/ml x h and 10322.2 +/- 11473.7 pg/ml x h, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative bioavailability of 5-aminosalicylic acid from a controlled release preparation and an azo-bond preparation

BACKGROUND

Knowledge of the bioavailability of 5-aminosalicylic acid (5-ASA, mesalazine) from the different 5-ASA-containing drugs is important for rational therapy of inflammatory bowel diseases.

METHODS

The local and systemic bioavailability of 5-ASA from a controlled release 5-ASA preparation (Pentasa--2, 4 or 6 g/day) was investigated and compared with the azo-bond 5-ASA preparation olsalazine (Dipentum--2 g/day) in 13 healthy volunteers during steady state conditions.

RESULTS

The therapeutically relevant parameter of 5-ASA at the rectal level, expressed as the mean concentration in faecal water, showed a significant trend towards higher concentrations with increasing Pentasa dose: 9.2 mmol/L, 19.0 mmol/L and 24.4 mmol/L, respectively. The concentration of olsalazine 2 g/day was 16.0 mmol/L. The concentration of the metabolite N-acetyl-5-aminosalicylic acid (Ac-5-ASA) did not rise with increasing Pentasa dose, indicating saturable presystemic acetylating capacity of 5-ASA. Total urinary excretion of 5-ASA and Ac-5-ASA, as a percentage of the daily ingested 5-ASA dose, remained constant on the three Pentasa doses, but there was a significant increase in the 5-ASA fraction. Mean steady state plasma concentrations of 5-ASA and Ac-5-ASA were significantly higher on Pentasa 4 g/day and 6 g/day than on 2 g/day. Values on Pentasa 2 g/day were comparable with those on olsalazine 2 g/day.

CONCLUSIONS

The study confirmed that 5-ASA is released from Pentasa in a predictable manner, the amount released increasing with dose. Olsalazine is an excellent generator of 5-ASA in the colon.

Effect of omeprazole and sucralfate on prepyloric gastric ulcer. A double blind comparative trial and one year follow up

This study compared healing rates, relief of symptoms, frequency of adverse events, and proportion of patients in remission after one year follow up in 104 patients with active prepyloric ulcer during treatment with 40 mg omeprazole once daily or 2 g sucralfate twice daily, using a randomised double blind controlled trial. Healing rates after two, four, and six weeks were (omeprazole/sucralfate) 49%/23%; 83%/59%; 90%/70% respectively. After two weeks, omeprazole was more efficient than sucralfate in relief of daytime and nocturnal epigastric pain, nausea, and heartburn. The proportion of patients in remission after one year follow up was significantly higher in the omeprazole group (p < 0.01). Of the healed patients ulcers recurred in 36% in the omeprazole group and in 46% in the sucralfate group. It is concluded that the ulcer healing rate was higher and symptom relief was more pronounced in the omeprazole group compared with the sucralfate group, and that more patients were still in remission after a one year follow up period.

Disposition of 5-aminosalicylic acid and N-acetyl-5-aminosalicylic acid in fetal and maternal body fluids during treatment with different 5-aminosalicylic acid preparations

STUDY OBJECTIVE

To determine the concentration of 5-aminosalicylic acid (5-ASA) and the metabolite N-acetyl-5-aminosalicylic acid (Ac-5-ASA) in the maternal and fetal plasma at delivery and in the maternal milk post partum.

DESIGN AND STUDY SUBJECTS

Pregnant and lactating women with chronic inflammatory bowel disease, treated with different pure 5-ASA preparations participated in the study. At delivery, samples of fetal and maternal plasma were obtained from nine women. The excretion in milk was measured and the time of medicine intake was registered during a 24 h period 2-4 weeks after delivery in 13 women.

RESULTS

Concentrations of 5-ASA in the fetal plasma were lower than in maternal plasma. Plasma concentrations of Ac-5-ASA were detectable in all the nine samples and similar levels in the mother and the fetus were found at the time of delivery. In three women 5-ASA was detected in the milk in low concentrations. The concentration of Ac-5-ASA in the milk varied considerably during the 24 h collection period, and also between individuals; its concentration tended to be higher than in the plasma. No time relation between medicine intake and maximal concentration in the milk was found. Based on the maximal Ac-5-ASA concentration and a milk intake of one liter/daily, the newborn receives less than 15 mg Ac-5-ASA daily.

CONCLUSION

The study indicates that treatment with pure 5-ASA preparations in conventional doses is without risk to the fetus and the newborn.

Specificity of the imino acid carrier in rat small intestine

The rat intestinal imino acid carrier is chloride independent, while in guinea pig and rabbit intestine it is chloride dependent. While non-alpha-amino acids do not significantly interact with guinea pig and rabbit imino acid carriers, inhibition studies had indicated that in rat small intestine beta-alanine, gamma-aminobutyric acid (GABA), and probably taurine might be transported by the imino acid carrier. The present study of rat jejunum demonstrates that the half-maximal activation concentration of beta-alanine (K1/2 beta-Ala) is identical to its inhibition constant (Ki beta-Ala) against GABA, that K1/2GABA is identical to KiGABA against beta-alanine, that proline and sarcosine have identical values of Ki against beta-alanine and GABA, and that Ki of beta-alanine and proline against sarcosine are equal to their K1/2 values. Taurine inhibits the transport of beta-alanine, and 300 mM proline and beta-alanine reduce the transport of taurine measured at 80 mM taurine to the level expected for the diffusive contribution, corresponding to Ki values equal to those against sarcosine. Thus the rat imino acid carrier is the principal carrier of taurine and the only carrier of beta-alanine and GABA. It is also demonstrated that alpha-amino-monocarboxylic acids with side chains in excess of one methyl group do not significantly interact with the imino acid carrier, and the lack of stereospecificity is confirmed.

[Sclerosing cholangitis and ulcerative colitis. Regional prevalence]

The aim of the study was to determine the prevalence of primary sclerosing cholangitis (PSC) in a regional population of patients with ulcerative colitis (UC). Three hundred and five patients with UC followed over a 12 year period were examined for elevations of serum alkaline phosphatase (> 280 U/l). Twenty four such patients were found. If no cause of these elevations were found by initial investigations, endoscopic retrograde cholangiography was performed in order to determine whether they had PSC. Eleven patients were found to have PSC (3.6%), of whom five had progressive disease, including two deaths from cholangio-carcinoma, during a six-year observation period. We found no certain relation between the extent, duration or activity of ulcerative colitis and the presence of PSC. Alkaline phosphatases were elevated up to 3.7 times the upper reference level, the aminotransferases were only found to be mildly elevated.

Bioavailability of four oral coenzyme Q10 formulations in healthy volunteers

The bioavailability of four different Coenzyme Q10 (CoQ) formulations was compared in ten healthy volunteers in a four-way randomised cross-over trial. The included formulations were: A hard gelatin capsule containing 100 mg of CoQ and 400 mg of Emcompress. Three soft gelatin capsules containing: 100 mg of CoQ with 400 mg of soy bean oil (Bioquinon); 100 mg of CoQ with 20 mg of polysorbate 80, 100 mg of lecithin and 280 mg of soy bean oil; and 100 mg of CoQ with 20 mg of polysorbate 80 and 380 mg of soy bean oil, respectively. The result suggests that the soya bean oil suspension of CoQ (Bioquinon has the highest bioavailability. A difference in basic AUC and AUC after p.o. administration of CoQ was observed with respect to sex. A characteristic two peak-pattern was observed at the concentration-time profile.

Very low intraluminal colonic pH in patients with active ulcerative colitis

Intraluminal gastrointestinal pH was measured in seven patients with active ulcerative colitis (four male, three female). A radiotelemetry capsule was used, and its location was determined by fluoroscopy. Satisfactory measurements were obtained from six, in all of whom pH levels were normal in the stomach and small intestine. Three patients also had normal pH values in the colon. However, in the remaining three patients very low pH levels (lowest values 2.3, 2.9, and 3.4) were found in the proximal parts of the colon. Five of the seven patients, including the three with low pH in the colon, underwent colectomy. The mechanism behind the low intraluminal pH in some patients with ulcerative colitis is speculative. Increased fecal concentrations of lactate occur in active disease, but some of the pH values measured in our study were below the pKa value of lactate. The study demonstrates that very low intraluminal pH levels in the colon occur in some patients with active ulcerative colitis. This might be an indicator of severe activity of the disease.

Bioavailability of 5-aminosalicyclic acid from slow release 5-aminosalicyclic acid drug and sulfasalazine in normal children

The bioavailability of a controlled release 5-aminosalicyclic acid preparation (Pentasa) was investigated in nine healthy children after a medication period of six days (1000 mg/day) and compared with sulfasalazine (Salazopyrin) (2000 mg/day). The local bioavailability in the distal gut lumen, reflected by the 5-aminosalicylic acid concentration in the fecal water, showed comparable values after Pentasa (4.44 mmol/liter) and Salazopyrin (6.25 mmol/liter). The concentration of N-acetyl-5-ASA was significantly higher after Pentasa, reflecting the more proximal release of 5-aminosalicyclic acid compared with Salazopyrin. No relation was found between the 5-aminosalicylic acid fecal water concentration water concentration and the 5-aminosalicylic acid dose per kilogram of body weight. The urinary excretion of 5-aminosalicylic acid and N-acetyl-5-aminosalicylic acid was higher after Pentasa than after Salazopyrin (32% vs 25%). Dose interval plasma concentration curves showed low values after both preparations. Based on the concept that the fecal water concentration is decisive for the efficacy of 5-aminosalicylic acid in distal inflammatory bowel disease, Pentasa treatment offers a relevant alternative in cases of Salazopyrin intolerance or allergy in children. The higher systemic bioavailability from Pentasa warrants monitoring of the renal function.

Pharmacokinetics of recombinant factor VIIa in the rat--a comparison of bio-, immuno- and isotope assays

Recombinant human factor VIIa (rFVIIa) is an activated coagulation factor for intravenous use as a haemostatic agent in haemophiliacs who generate antibodies against factor VIII or IX. Plasma kinetic studies are important for the understanding of the action of rFVIIa which is exerted in the vascular compartment of the body, more specifically on the vessel walls at the site of injury. In the present study, rats were dosed 100 or 500 micrograms/kg 125I-rFVIIa i.v., without any side effects being observed, and the plasma profile of rFVIIa was studied by 3 different assays that were shown to correlate well at early times post-dose: trichloroacetic acid (TCA)-precipitable drug-related radioactivity, rFVIIa antigen determination by ELISA technique, and the assay of clot activity which is the only clinically applicable assay. The plasma concentration curve could be resolved into 1-3 exponentials, depending on the FVIIa detection principle that was employed. Initially, there was a short (ca. 10 min) phase of increasing concentrations before the attainment of Cmax. This was followed by a plasma recovery (Cmax x plasma volume/dose) in the vicinity of one half of the administered dose. The initial volume of distribution (V1) corresponded to the vascular compartment whereas the volume of distribution at steady state (Vss) was somewhat larger. Whole body clearance (CL-B) of rFVIIa was approx. 1 ml/min per kg, and mean residence time (MRT) and the half-life assumed to be associated with the loss of biological activity was approx. 1 h and 20-45 min, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Single-dose and steady-state pharmacokinetics of diltiazem administered in two different tablet formulations

Single-dose and steady state pharmacokinetics of diltiazem administered in two different oral formulations were assessed with particular reference to rate and extent of absorption. Following single dose administration a significant difference in tmax was observed (2.9 +/- 1.9 and 6.8 +/- 2.6 hr respectively) whereas differences in AUC, t1/2 and Cmax were not significant. The AUC (mean +/- S.D.) values following single dose administration of Cardil and Cardizem were 678.4 +/- 321.5 and 948.6 +/- 580.6 ng.ml-1.hr respectively. The mean and the 95% confidence limits for the observed ratio AUCCardil/AUCCardizem are 0.89 and 0.44-1.34 respectively. At steady-state a significant difference between Cmax/Cmin and tmax was seen Cmax/Cmin being 4.9 and 3.2 respectively and Tmax being 2.7 +/- 2.0 and 6.0 +/- 2.8 hr respectively, whereas Cmax and AUC did not differ significantly. The AUC (mean +/- S.D.) values in steady state of Cardil and Cardizem were 880.1 +/- 399.8 and 1056.8 +/- 509.8 ng.ml-1.hr respectively. The mean and the 95% confidence limits for the observed ratio AUCCardil/AUCCardizem are 0.96 and 0.66-1.26 respectively. Although the observed ratios AUCCardil/AUCCardizem in both the single-dose and the steady-state study do not differ significantly from 1.0, the confidence limits exceed the acceptable values given by Poulsen & Juul (personal communication 1990) (a 20% decrease or increase of the ratio to 0.8 or 1.2).

Primary sclerosing cholangitis in patients with ulcerative colitis

The prevalence of primary sclerosing cholangitis (PSC) in patients with ulcerative colitis (UC) attending the Depts. of Medical and Surgical Gastroenterology, Aalborg Hospital, during a 12-year period, was determined. All patients with an alkaline phosphatase (ALP) value above the normal range were investigated. Of 305 patients with UC, 24 patients had elevated ALP values, and 11 of these (3.6% of the study population), 4 males and 7 females, were found to have PSC by direct cholangiography. In five patients the disease worsened (two patients died of cholangiocarcinoma), in four it was stationary, and in two patients the disease improved during a mean observation period of 6 years. No differences in location of disease, disease activity, or duration of disease were found between patients with UC and PSC and patients with UC without PSC. The ALP values were raised to a mean of 3.7 times the upper normal limit (observed range, 1.5-5.5 times the upper normal limit). Aspartate aminotransferase was moderately elevated in most patients, but no other abnormal biochemical liver test results were observed at onset. The results of our study indicate that PSC is the major cause of raised ALP values in patients with UC; thus cholangiography should be performed in UC patients with unexplained elevated ALP levels. A prognostic indicator is needed to predict the individual prognosis and to determine the optimal timing of liver transplantation.

Pharmacokinetics of 5-aminosalicylic acid in man following administration of intravenous bolus and per os slow-release formulation

The fate of 5-aminosalicylic acid (5-ASA), which is used in the treatment of chronic inflammatory bowel diseases, was studied in six healthy volunteers receiving doses of 100 mg and 250 mg intravenous bolus as well as 250 mg per os (slow release). Following intravenous administration, the drug was rapidly eliminated with a plasma half-life of about 40 min, mainly due to rapid metabolism. No parent drug was recovered in feces, and the total recovery following oral administration (30%) was significantly lower than following the intravenous doses (77% and 72%). Nonlinear pharmacokinetics were suggested as the 2.5-fold increase in intravenous dose was followed by a significant relative increase (greater than 2.5) in the renal elimination of 5-ASA, as well as a significant decrease (less than 2.5) in the elimination of the metabolite N-acetyl-5-ASA. There was also a trend towards a decreasing total body clearance and metabolic ratio. The present study confirms earlier findings on the pharmacokinetics of 5-ASA and suggests a possible saturation of the N-acetylating system in the dose range studied. This may be of interest in the design of controlled-release formulations and dosage regimes for the treatment of diseases of the small-bowel, where 5-ASA is easily absorbed. Further, for the first time, a marked difference in the intestinal fate compared to the systemic fate of the drug is demonstrated, suggesting alternative presystemic metabolism of 5-ASA, which may bear relevance to its mode of action. Further studies on the pharmacokinetics of 5-ASA, preferably in patients, are warranted.

[Primary sclerosing cholangitis]

Primary sclerosing cholangitis (PSC) is an uncommon disorder of unknown etiology, characterized by chronic inflammation and fibrosis of the intra- and extrahepatic bile ducts. PSC is commonly associated with chronic inflammatory bowel disease, especially ulcerative colitis, and often in younger men with an extensive colitis. The diagnosis is made by endoscopic retrograde cholangiography. The characteristic findings are multiple strictures and dilatations of the intra- and extrahepatic bile ducts. Patients with PSC usually have a cholestatic biochemical profile. The liver biopsy findings are often non-specific. Different survivals in these patients have been described. However, asymptomatic patients seems to have a more favorable prognosis. The only curative treatment is liver transplantation.

Availability of mesalazine (5-aminosalicylic acid) from enemas and suppositories during steady-state conditions

The local and systemic bioavailability of a mesalazine enema (Pentasa, Ferring A/S, Denmark) and a mesalazine suppository (Pentasa, Ferring) was assessed during steady-state conditions. Eleven healthy subjects took 1 g of the enema or the suppository twice daily for 1 week, with a drug-free period of at least 1 week in between. At the end of each treatment period the urine and faeces were collected for 48 h, and the concentrations of mesalazine and the metabolite acetyl-mesalazine were measured. Plasma concentrations of drug and metabolite were measured hourly during a 12-h dose interval. The faecal water concentration of mesalazine was significantly higher after suppository treatment (55.7 mmol/l) compared with enema treatment (31.7 mmol/l) (p less than 0.01). The systemic absorption was low; 15% of daily mesalazine dose was recovered in urine after enema treatment and 10% after suppositores (p less than 0.01). Plasma concentrations were low, and no accumulation of either mesalazine or acetyl-mesalazine occurred. In conclusion, the enema and the suppository can be continuously administered as 1 g of mesalazine twice daily, respectively, giving high faecal water concentrations of mesalazine and a low systemic absorption.

Tetraethylammonium and p-aminohippurate as clearance markers for renal plasma flow in the rat during saline and glucose infusion

Renal plasma clearances (C) of 14C-tetraethylammonium (TEA) and p-aminohippurate (PAH) as estimates of arterial renal plasma flow (ARPF) were evaluated in anesthetized rats during control conditions and during intravenous glucose infusion. Venous renal blood flow was measured directly by means of a servo-controlled pump, keeping the renal venous pressure constant. Arteriovenous extraction fractions (E = 1 - P(renal venous)/P(renal arterial)) for PAH averaged 88.3 +/- (SE) 0.8% in control rats and 82.0 +/- 0.9% in glucose-infused rats (p less than 0.001); E(TEA) averaged 92.0 +/- 0.6 and 90.1 +/- 0.6%, respectively (p less than 0.05). Under both experimental conditions, (C/E)PAH did not differ significantly from ARPF, while (C/E)TEA underestimated ARPF; the rate of extraction of TEA exceeded the rate of excretion by 15-20%, probably due to accumulation of TEA in renal tissue. It is concluded that, when corrected for E, C(PAH) is in general a more accurate estimate for ARPF than C(TEA). However, under conditions involving changes in plasma glucose levels C(TEA) may provide a better estimate of the effective renal plasma flow than C(PAH).

Ion concentration and haematocrit as determinants of impedance in an erythrocyte suspension model of renal medullary tissue

In order to analyse the respective roles of ion concentration and fractional volume of the interstitial compartment as determinants of the impedance, Z, of renal medullary tissue, a model was needed in which both these factors could be varied independently. An array of blood cell suspensions ions in saline (different haematocrit values and different NaCl concentrations) was used for this purpose. It was found that: (i) up to a measuring frequency of about 10 kHz, the complex consisting of needle electrodes and 'tissue' can be regarded as serially connected resistances, R, and capacitances; (ii) the frequency range 3-10 kHz can be regarded as optimal since it simultaneously assures low electrode polarization and a negligible role of tissue capacitance; (iii) increasing the haematocrit had two consequences--a reduced contribution of polarization impedance to the total impedance measured and a decreased sensitivity of ion concentration measurement from R-1 (conductance); (iv) passive electrical properties of renal medullary tissue were close to those of a 75% haematocrit cell suspension; (v) since in high haematocrit suspensions the resistive component of impedance predominates, within the frequency range 3-10 kHz either conductance or admittance, Z-1, can be used as an index of ion concentration; and (vi) impedance changes in kidney tissue are primarily determined by fluctuations of ion concentration with a less important contribution from interstitial volume changes.

Topical and systemic availability of 5-aminosalicylate: comparisons of three controlled release preparations in man

The bioavailability of three pure 5-aminosalicylic (5-ASA) preparations (Asacol, Claversal, and Pentasa) was studied in 8 ileostomy patients and 12 normal subjects after 6 days of treatment with 2000 mg 5-ASA. The local bioavailability, reflected by the 5-ASA concentration was thereby measured at two clinically relevant areas of the gut: at the entrance to, and the exit from the colon. Estimates of the systemic bioavailability were obtained from the urinary excretions and the plasma values of 5-ASA and Acetyl-5-ASA (Ac-5-ASA) during the three regimens. The three preparations studied are designed to release 5-ASA at different levels in the intestine, but there was no significant difference in the 5-ASA concentrations in the ileostomy effluents (Asacol 1.8 mmol/L, Claversal 3.4 mmol/L, Pentasa 2.0 mmol/L, median values). However, we found a smaller urinary excretion of 5-ASA and Ac-5-ASA (5.2% vs Claversal 27.9% and Pentasa 23.0%, median values of ingested daily dose) and a lower concentration of Ac-5-ASA in the ileostomy effluents after Asacol treatment (0.8 mmol/L, median value) which indicates a more distal release from this preparation compared with Claversal (2.4 mmol/L, median value) and Pentasa (5.5 mmol/L, median value). In normal subjects a higher faecal water concentration of 5-ASA was found after Asacol (9.8 mmol/L, median value) compared with Claversal (5.0 mmol/L, median value), whereas no difference between the faecal water concentrations of Ac-5-ASA was found (Asacol 21.5 mmol/L, Claversal 21.6 mmol/L, median values). This can be explained by a larger systemic absorption of 5-ASA from Claversal, and accordingly Claversal treatment resulted in the largest urinary excretion of 5-ASA and Ac-5-ASA (43.7% vs Asacol 35.6% and Pentasa 31.6%, median values of ingested daily dose). The high Ac-5-ASA concentration in the ileostomy effluents and in the faeces after Pentasa, and the low plasma values, indicate a slow 5-ASA release from this preparation throughout the small and large intestine. The results of the study indicate that Asacol is released in the distal part of the small intestine, that Pentasa is gradually released in the small and large intestine, and that Claversal shows an intermediate release pattern.

Renal tissue impedance: responses of the real and imaginary component to experimental variations in medullary electrolytes

In order to assess the renal corticomedullary electrolyte gradient, electrical impedance (zeta) and phase angle (phi) were measured in the in-situ kidney of anaesthetized rats. A set of platinum/iridium needle electrodes was used, and the frequency (f) of the measuring current was varied between 0.5 and 50 kHz. zeta and its imaginary component (chi c) fell sharply as f increased from 0.5 to 3.5 kHz, and then decreased slowly or stabilized, whereas the real component (R) decreased progressively over the entire f range. Ion concentration in the renal medulla was experimentally lowered by administration of furosemide or hypertonic mannitol or by inducing a haemorrhage, and raised by infusing hypertonic NaCl solution. Both R and chi c varied inversely with tissue electrolyte concentration. Raising f from 3.5 to 10 and further to 20 kHz did not significantly amplify the changes in zeta. Within this frequency range R was not a more sensitive index of tissue electrolyte changes compared with overall zeta-value. The results verify previous empirical data indicating that changes in medullary tissue electrolytes can be dynamically estimated by monitoring tissue impedance.