Use of unlicensed and off-label medications in paediatric gastroenterology with a review of the commonly used formularies in the UK

BACKGROUND

Use of unlicensed and off-label medications is common in hospital based paediatric practice. Whilst inpatient prescription can be closely monitored within the hospital setting, it is subspecialties like paediatric gastroenterology, caring for chronically ill children on an outpatient basis that require administration of regular medications in the community. Local practitioners rely on available paediatric formularies or information provided by the tertiary unit for monitoring and dispensing further prescriptions.

AIM

To assess the proportion of unlicensed and off-label medications prescribed in a paediatric gastroenterology unit to children discharged to the community and assess adequacy of information about these medications in commonly used British formularies.

METHODS

All prescriptions prescribed over a six-month period (Jan-Jul 2002) either in the paediatric gastroenterology outpatient department or for children discharged home after an inpatient stay, were retrieved from the pharmacy database. The main outcome measures were to assess the proportion of medications prescribed for unlicensed or off-label use.

RESULTS

308 patients received 777 prescriptions of which 384 (49%) were for unlicensed or off-label use. Of these 291 (76%) were off-label; 208 in relation to indication and 83 to child's age. 93 of the prescribed medications were unlicensed; 37 were due to manipulation of formulation. Of the commonly used formularies in the UK, only 'Medication for Children(R)' contained dosage information on more than half (9/13) of the most often prescribed off-label/unlicensed medications in paediatric gastroenterology.

CONCLUSIONS

Use of unlicensed and off-label medications remains a problem in paediatric practice. Until licensing laws change and more drugs are licensed in children, paediatric gastroenterologists remain responsible for provision of information to families, local practitioners, nurses and pharmacists. Of the commonly used formularies, 'Medicines for Children' is the most detailed and comprehensive, and should be available to all general practitioners and pharmacists in the UK. Clear communication between specialist units and local practitioners is imperative to ensure safe and effective prescribing to children.

Remifentanil by patient-controlled analgesia compared with intramuscular meperidine for pain relief in labour

BACKGROUND

The pharmacokinetics of remifentanil suggests that it may be suitable for analgesia during labour.

METHODS

In an open pilot study, 36 women requesting meperidine for analgesia were recruited early in labour and randomized to receive either meperidine i.m. or remifentanil given as patient-controlled analgesia (PCA). Pain severity, sedation and anxiety were assessed with visual analogue scales and overall effective analgesia was assessed by the woman and midwife.

RESULTS

The pain scores were lower in the remifentanil group: median pain score at 60 min was 72 mm for meperidine and 48 mm for remifentanil (P=0.004) and median maximum pain score during the first 2 h was 82.5 mm for the meperidine group and 66.5 mm for the remifentanil group (P=0.009). Both the midwives' and the women's assessments of overall effective analgesia were higher in the remifentanil group [Likert scale (5 = excellent to 1 = poor): chi2=12.10, P=0.002 for mothers' assessment; chi2=12.80, P=0.002 for midwives' assessment].

CONCLUSION

In this pilot study, remifentanil by PCA gave better pain relief to mothers in labour than intramuscular meperidine. However, remifentanil is a potent respiratory depressant and adequate continuous monitoring is necessary.

A primary school outbreak of pharyngoconjunctival fever caused by adenovirus type 3

High rates of absenteeism in a North Queensland primary school, due to eye irritation, fever, headache, and stomach pain, were reported to the Tropical Public Health Unit in October 2000. Subsequent investigation demonstrated that the symptoms were due to adenovirus infection. Symptoms were consistent with a diagnosis of pharyngoconjunctival fever. At the height of the outbreak, about 40 per cent of students were absent. There was a strong association between the development of symptoms, and having been swimming on a recent school camp. Adenovirus could not be isolated from swimming pool water from the resort where the camp had been held. However, when inspected the swimming pool was not adequately chlorinated or maintained. It is probable that adenovirus infection was transmitted via swimming pool water at the school camp, and the outbreak might have been avoided by higher standards of swimming pool maintenance.

Induction or suppression of a B cell-specific response to self antigen in vivo is dependent upon dendritic cell activation via the TNF-alpha receptor at the time of antigen uptake

In this study we show that the retinal autoantigen, S-antigen, contains a functional TNF-alpha homologous domain which stimulates maturation and differentiation of cultured dendritic cells (DC) or tissue DC via the p55 TNF-alpha receptor. Tissue DC became more dendritiform in shape, and migrated into culture supernatant. S-antigen also stimulated accumulation of cell surface MHC class II antigen with a corresponding loss of acidic intracellular vesicles, and induced IL-1beta and IL-12 mRNA expression in cultured bone marrow-derived DC. In addition, cultured splenic DC primed immune responses to S-antigen in vivo in the absence of other, exogenous cytokine sources. DC pulsed with either retinal S-antigen or another retinal autoantigen, interphotoreceptor retinoid binding protein (IRBP), were able to stimulate naive T cell proliferation in vitro, but only S-antigen-pulsed DC were able to induce an immune response in vivo and initiate antibody class switching. In contrast, IRBP-pulsed DC had no detectable in vivo priming effect and IgG antibody levels remained suppressed even after immunization with IRBP in complete Freund's adjuvant. These results indicate that DC from the same precursor population can either induce or suppress a B cell-specific response to self antigen in vivo, the outcome being dependent upon DC activation at the time of antigen uptake and presentation.

Cloning and characterization of zebrafish smad2, smad3 and smad4

smad genes encode transcription factors involved in the signal transduction of members of the TGFbeta superfamily. We report here the cloning, characterization and genomic mapping of smad2, smad3 and smad4 from the zebrafish, Danio rerio. In Xenopus, smad2 overexpression has been shown to interfere with gastrulation and dorsal cell fate specification. However, full-length zebrafish smad2, although functionally active in Xenopus explants, has no effect when overexpressed in zebrafish embryos. In contrast, an N-terminally truncated, constitutively active version of Smad2 protein causes severe dorsalization or partial secondary axis formation, pointing to a role of Smad2 during mesoderm and axis formation. The temporal and spatial expression patterns of zebrafish smad2, 3 and 4 were investigated by developmental RT-PCR and whole mount in-situ hybridization. All three genes show strong and ubiquitous maternal expression. Zygotic expression is weak and ubiquitous in the case of smad2, and strong and ubiquitious in the case of smad4, while smad3 shows a spatially restricted zygotic expression pattern. It is expressed in migrating neural crest cells of the trunk and a subset of cells in the diencephalon in close proximity to the expression domain of the Nodal-related protein Cyclops/Ndr2/Znr1, a potential signal upstream of Smad2/3 required for eye-field separation and floor plate specification. Overexpression of truncated smad2 in cyclops mutant embryos leads to a rescue of the eye and floorplate defects. These data suggest that Smad2 acts as a mediator of Nodal signals during zebrafish midline signaling, while Smad3 might be involved in later steps of eye field separation.

Essential role of Bmp7 (snailhouse) and its prodomain in dorsoventral patterning of the zebrafish embryo

Bone morphogenetic proteins (Bmps) are signaling molecules that have been implicated in a variety of inductive processes. We report here that zebrafish Bmp7 is disrupted in snailhouse (snh) mutants. The allele snh(st1) is a translocation deleting the bmp7 gene, while snh(ty68) displays a Val->Gly exhange in a conserved motif of the Bmp7 prodomain. The snh(ty68) mutation is temperature-sensitive, leading to severalfold reduced activity of mutant Bmp7 at 28 degrees C and non-detectable activity at 33 degrees C. This prodomain lesion affects secretion and/or stability of secreted mature Bmp7 after processing has occurred. Both snh(st1) and snh(ty68) mutant zebrafish embryos are strongly dorsalized, indicating that bmp7 is required for the specification of ventral cell fates during early dorsoventral patterning. At higher temperature, the phenotype of snh(ty68) mutant embryos is identical to that caused by the amorphic bmp2b mutation swirl swr(ta72) and similar to that caused by the smad5 mutation somitabun sbn(dtc24). mRNA injection studies and double mutant analyses indicate that Bmp2b and Bmp7 closely cooperate and that Bmp2b/Bmp7 signaling is transduced by Smad5 and antagonized by Chordino.

[The Bavarian Thromboembolic Risk Cohort Study (BATER). Study protocol, state of the investigation and first results]

OBJECTIVE

Familiar venous thromboembolic disease (VTE) is known to be related with factor V Leiden mutation (FVL), but also with other genetic markers. It is the objective to investigate of the BATER-study in a representative Bavarian cohort, and to assess whether they could predict VTE events. This paper shortly describes the study protocol, gives an overview of planned sub-studies, and provides first results of the historic cohort analysis.

PATIENTS AND METHODS

The baseline survey of the cohort study of Bavarian women aged 18-49 years (random sample from the population) was performed in two samples in 1996 and 1997. It was planned to estimate a prevalence and predictive value of potential markers of VTE in a historic--prospective as well as concurrent approach with annual follow-up of the cohort. This representative cohort should build a basis for nested case-control studies and serve as a reference group for other analytical epidemiological studies in young women. 1685 women were ascertained (response rate 61%), underwent an inquiry, and provided blood samples for a blood bank; for this paper, complete data are available from 1650 women. Laboratory parameters were measured to determine APC resistance, FVL-mutation, antithrombin-, protein C and S deficiency, and were correlated to the results of a detailed, life-time history of thrombembolic events.

RESULTS

The prevalence of FVL mutation in the sample was 5.7% (95% confidence interval 4.6-6.6%). Other genetic VTE risk markers were observed to be less frequent than 1%. The positive predictive value (pPV) of FVL mutation for a VTE event is about 7%, but for a positive family history of VTE (first grade relatives) 3% only.

CONCLUSIONS

VTE events are rare in the German population of young women, even in cases of FVL mutation. A positive family history is rarely associated with the occurrence of VTE in women under 50 years of age, and the predictive value of FVL mutation is low. Therefore, a screening for FVL mutation is not justified unless there is suspicion of a high VTE risk for other reasons.

Continuous intravenous infusion in athymic (nude) rats: an animal model for evaluating the efficacy of anti-cancer agents

The athymic (nude) rat (rnu/rnu) has been used for a number of years in research into various human tumours involving xenotransplantation. We now report the validation of a continuous intravenous infusion method in nude rats using a tail cuff tether, which enables the study of the efficacy of novel anti-cancer materials in this mutant strain, using intravenous infusion and with no restriction of the animals or of the tumour implantation sites by jackets. Ten animals each had a cannula surgically implanted into the vena cava via the femoral vein and exteriorized via a tail cuff. Animals were housed singly in conventional cages following surgery. Following a recovery period of 5 days all animals were continuously infused with physiological saline at an infusion rate of 0.5 ml/h for a further 37 days. Body weights and food consumption were recorded weekly. Blood samples were taken approximately 14 days post-surgery and analysed for haematology and clinical chemistry parameters. All animals were successfully cannulated, and no unexpected adverse clinical signs were noted during the recovery period and the 37 days of infusion. The results demonstrate that it is possible to surgically cannulate the femoral vein of athymic (nude) rats and infuse them in conventional cages for a period of up to 37 days with minimal adverse effects. The minimal restraint required provides benefits both to the animal and to the conduct of studies such as assessment of tumour growth in the absence of a jacket. Recent work has demonstrated that the same techniques can be successfully applied to the nude mouse.

Smad1 and Smad5 have distinct roles during dorsoventral patterning of the zebrafish embryo

Smad1 and smad5 encode transcription factors that have been implicated in the transduction of signaling by the bone morphogenetic proteins Bmp2 and/or Bmp4. Here we report the characterization of Smad1 and Smad5 from the zebrafish, Danio rerio. Although smad1, smad5, bmp2b, and bmp4 are all expressed during gastrulation and although all four proteins have ventralizing activities, they appear to play distinct roles during dorsoventral pattern formation. smad1 expression starts shortly before the onset of gastrulation. It is expressed on the ventral side of the embryo, whereas smad5 transcripts are both maternally and zygotically provided and ubiquitously distributed. Injection studies and mutant analyses suggest that the ventral smad1 expression is positively regulated by Bmp2b, but not by Bmp4 signaling, whereas smad5 expression is independent of Bmp2b. Also, the dorsalized phenotype of bmp2b-mutant embryos can be rescued by exogenous Smad1, but not by Smad5. Together, these data suggest that smad1 acts later than smad5 and is itself a transcriptional target of Smad5-mediated Bmp2b signaling. During later stages of development, smad1 is expressed in eyes, dorsal cells of rhombomeres 1, 3, and 5, and somites, with highest mRNA levels in the presumptive sclerotome and adaxial regions near the notochord. Injection experiments indicate that this somitic smad1 expression is positively regulated by hedgehog signaling from the dorsal midline, thus perhaps accounting for the recently reported sonic hedgehog-induced competence of sclerotomal cells to Bmp2/4 signals.

Quantification of horseradish peroxidase delivery into the arterial wall in vivo as a model of local drug treatment: comparison between a porous and a gel-coated balloon catheter

PURPOSE

To quantify horseradish peroxidase (HRP) delivery into the arterial wall, as a model of local drug delivery, and to compare two different percutaneous delivery balloons.

METHODS

Perforated and hydrophilic hydrogel-coated balloon catheters were used to deliver HRP in aqueous solution into the wall of porcine iliac arteries in vivo. HRP solutions of 1 mg/ml were used together with both perforated and hydrophilic hydrogel-coated balloon catheters and 40 mg/ml HRP solutions were used with the hydrogel-coated balloon only. The amount of HRP deposited in the arterial wall was then determined photospectrometrically.

RESULTS

Using the 1 mg/ml HRP solution, the hydrogel-coated balloon absorbed 0.047 mg HRP into the coating. Treatment with this balloon resulted in a mean vessel wall concentration of 7.4 microg HRP/g tissue +/- 93% (standard deviation) (n = 7). Treatment with the hydrogel-coated balloon that had absorbed 1.88 mg HRP into the coating (using the 40 mg/ml HRP solution) led to a mean vessel wall concentration of 69.5 microg HRP/g tissue +/- 74% (n = 7). Treatment with the perforated balloon using 1 mg/ml aqueous HRP solution led to a mean vessel wall concentration of 174 microg/g +/- 81% (n = 7). Differences between the hydrogel-coated and perforated balloons (1 mg/g solutions of HRP) and between hydrogel-coated balloons (0.047 mg vs 1.88 mg absorbed into the balloon coating) were significant (p < 0.05; two-sided Wilcoxon test).

CONCLUSIONS

The use of a perforated balloon catheter allowed the delivery of a higher total amount of HRP compared with the hydrogel-coated balloon, but at the cost of a higher systemic HRP application. To deliver 174 microg HRP per gram of vessel wall with the perforated balloon, 6.5 +/- 1.5 mg HRP were lost into the arterial blood (delivery efficiency range = 0.2%-0.3%). With 0.047 mg HRP loaded into the coating of the hydrogel balloon, 7.4 microg HRP could be applied to 1 g of vessel wall (delivery efficiency 1.7%), and with 1.88 mg HRP loaded into the coating of the hydrogel balloon, 69.5 microg HRP could be applied per gram of vessel wall (delivery efficiency 0.6%).

The smad5 mutation somitabun blocks Bmp2b signaling during early dorsoventral patterning of the zebrafish embryo

Signaling by members of the TGFbeta superfamily is thought to be transduced by Smad proteins. Here, we describe a zebrafish mutant in smad5, designated somitabun (sbn). The dominant maternal and zygotic effect of the sbntc24 mutation is caused by a change in a single amino acid in the L3 loop of Smad5 protein which transforms Smad5 into an antimorphic version, inhibiting wild-type Smad5 and related Smad proteins. sbn mutant embryos are strongly dorsalized, similarly to mutants in Bmp2b, its putative upstream signal. Double mutant analyses and RNA injection experiments show that sbn and bmp2b interact and that sbn acts downstream of Bmp2b signaling to mediate Bmp2b autoregulation during early dorsoventral (D-V) pattern formation. Comparison of early marker gene expression patterns, chimera analyses and rescue experiments involving temporally controlled misexpression of bmp or smad in mutant embryos reveal three phases of D-V patterning: an early sbn- and bmp2b-independent phase when a coarse initial D-V pattern is set up, an intermediate sbn- and bmp2b-dependent phase during which the putative morphogenetic Bmp2/4 gradient is established, and a later sbn-independent phase during gastrulation when the Bmp2/4 gradient is interpreted and cell fates are specified.

Lipopeptides as dimerization inhibitors of HIV-1 protease

In AIDS therapy, attempts have been made to inhibit the virus-encoded enzymes, e.g. HIV-1 protease, using active site-directed inhibitors. This approach is questionable, however, due to virus mutations and the high toxicity of the drugs. An alternative method to inhibit the dimeric HIV protease is the targeting of the interface region of the protease subunits in order to prevent subunit dimerization and enzyme activity. This approach should be less prone to inactivation by mutation. A list of improved 'dimerization inhibitors' of HIV-1 protease is presented. The main structural features are a short 'interface' peptide segment, including non-natural amino acids, and an aliphatic N-terminal blocking group. The high inhibitory power of some of the lipopeptides [e.g. palmitoyl-Tyr-Glu-Leu-OH, palmitoyl-Tyr-Glu-(L-thyronine)-OH, palmitoyl-Tyr-Glu-(L-biphenyl-alanine)-OH] with low nanomolar Ki values in the enzyme test suggests that mimetics with good bio-availability can be derived for AIDS therapy.

Electric field-directed cell motility involves up-regulated expression and asymmetric redistribution of the epidermal growth factor receptors and is enhanced by fibronectin and laminin

Wounding corneal epithelium establishes a laterally oriented, DC electric field (EF). Corneal epithelial cells (CECs) cultured in similar physiological EFs migrate cathodally, but this requires serum growth factors. Migration depends also on the substrate. On fibronectin (FN) or laminin (LAM) substrates in EF, cells migrated faster and more directly cathodally. This also was serum dependent. Epidermal growth factor (EGF) restored cathodal-directed migration in serum-free medium. Therefore, the hypothesis that EGF is a serum constituent underlying both field-directed migration and enhanced migration on ECM molecules was tested. We used immunofluorescence, flow cytometry, and confocal microscopy and report that 1) EF exposure up-regulated the EGF receptor (EGFR); so also did growing cells on substrates of FN or LAM; and 2) EGFRs and actin accumulated in the cathodal-directed half of CECs, within 10 min in EF. The cathodal asymmetry of EGFR and actin staining was correlated, being most marked at the cell-substrate interface and showing similar patterns of asymmetry at various levels through a cell. At the cell-substrate interface, EGFRs and actin frequently colocalized as interdigitated, punctate spots resembling tank tracks. Cathodal accumulation of EGFR and actin did not occur in the absence of serum but were restored by adding ligand to serum-free medium. Inhibition of MAPK, one second messenger engaged by EGF, significantly reduced EF-directed cell migration. Transforming growth factor beta and fibroblast growth factor also restored cathodal-directed cell migration in serum-free medium. However, longer EF exposure was needed to show clear asymmetric distribution of the receptors for transforming growth factor beta and fibroblast growth factor. We propose that up-regulated expression and redistribution of EGFRs underlie cathodal-directed migration of CECs and directed migration induced by EF on FN and LAM.

The distribution of pepsinogen within the abomasa of cattle and sheep infected with Ostertagia spp. and sheep infected with Haemonchus contortus

The effect of nematode infections on the production of pepsinogen by ruminants was investigated immunohistochemically and biochemically. Abomasal tissues were collected from parasite-naive cattle and sheep, from sheep infected with predominantly Ostertagia circumcincta, sheep infected experimentally with Haemonchus contortus and cattle infected with Ostertagia ostertagi. Pepsinogen was also assayed biochemically in homogenates of fundic mucosae from sheep infected with predominantly O. circumcincta. Infection with Ostertagia spp. parasites was associated mainly with nodular hyperplasia, resulting in increased numbers of cells that produce both pepsinogen and mucus. Measured biochemically, nodules contained more pepsinogen than adjacent more normal mucosa (p < 0.05), and this effect was largely attributable to the greater mass of nodules. Infection of sheep with H. contortus was associated with generalised hyperplasia, characterised by increased numbers of mucopeptic cells and in at least one animal with reductions in parietal cell numbers. At the same time, the zymogen granule content of chief cells was reduced. Similar changes were occasionally seen in sheep infected predominantly with O. circumcincta. Generalised hyperplasia is likely to be indicative of the presence of ambulatory parasitic stages as opposed to those confined to nodules. The potential for the enhanced production of pepsinogen by increased numbers of cells with a joint mucous cell and zymogenic cell phenotype may offset decreases in the numbers of chief cells or reductions in chief cell activity.

Resistance to activated protein C in women using oral contraceptives

Resistance to activated protein C (APC resistance) is an important and common risk factor for deep vein thrombosis. The majority of patients with APC resistance carry a mutation on the factor V gene at nucleotide position 1691 (G/A), called factor V Leiden mutation. Besides the factor V Leiden mutation several acquired risk factors like lupus anticoagulant, elevated levels of acute phase proteins (increased plasma levels of factor VIII and fibrinogen), pregnancy, or the use of oral contraceptives are known to induce APC resistance in plasma. We studied the effect of oral contraceptives (OC) on hemostasis variables known to be risk factors for venous thromboembolism, especially looking for acquired APC resistance and the plasmatic factors of the protein C system. We studied 821 women, who were randomly selected and enrolled in the BATER- cohort study (Bavarian Thromboembolic Risk Study), which was carried out in Bavaria (Germany) from 1996 to 1997. Current use of any OC type compared with noncurrent use showed a significantly impaired response to APC. There was no difference in APC response among women currently using OCs of different generations. Coagulation factor VIII was the only factor of the protein C pathway that was not altered under OC use. All other plasmatic factors of the protein C system changed in the expected range as described before. On the other hand, coagulation factor VIII was the only factor of the protein C system which negatively correlated with the APC response in the assays applied. Thus, APC resistance is significantly lower in OC users than in nonusers but cannot be attributed to increased factor VIII levels. Whether a decreased response to APC in OC users is of clinical relevance has to be proven in further studies.