How adverse drug reactions can play a role in innovative drug research

We describe how adverse drug reactions (ADRs) can play an important role in pharmaceutical research and drug development. Not only do ADRs represent the risks and drawbacks associated with drugs but they can also be related to other knowledge available in pharmaceutical and medical research. We offer a model that can be used to systematically map the pathways through which ADRs can lead to innovative research. These pathways include chemical, therapeutic or pathophysiological steps that can be taken to arrive at new knowledge based on ADRs. We used the development of angiotensin-converting enzyme inhibitors, especially captopril, as a case study. The similarity between the ADR profiles of captopril and penicillamine was a starting point for further innovation. Historical analysis shows that in several instances research in the field of angiotensin-converting enzyme inhibitors has been triggered by ADRs. The model presented here might be applicable to other areas of innovative drug research.     

Recombinant human stem cell factor stimulates growth of a human glioblastoma cell line expressing c-kit protooncogene.

The growth of a panel of eight different human glioblastoma cell lines was examined in a human tumor cloning assay in agar, a tritiated thymidine uptake assay, and by counting cell numbers, in cultures performed in the absence or presence of increasing concentrations (1 to 100 ng/ml) of recombinant human stem cell factor (SCF). Growth of 7 of 8 cell lines was not significantly and reproducibly affected by recombinant human SCF. However, growth of the CRL 1620 cell line could be stimulated up to 5-fold by the cytokine. In contrast to the other cell lines investigated, CRL 1620 expressed the c-kit protooncogene assessed on the mRNA and protein level. Furthermore, SCF-induced proliferation of CRL 1620 cells was sensitive to the tyrosine kinase inhibitor erbstatin. Our data suggest that SCF can be operative in growth modulation of malignant cells outside the hematopoietic system, and this finding should be further studied for its possible clinical implications.     

[3H]Ketanserin labels 5-HT2 receptors and α1-adrenoceptors in human and pig brain membranes

The binding characteristics of [3H]ketanserin (a reported selective radioligand for serotonin 5-HT2 receptors) and [125I]BE 2254 (which labels selectively alpha 1-adrenoceptors) were characterized in brain frontal cortex membranes of pig and man. Saturation experiments indicated that both radioligands label apparently a homogeneous class of binding sites in human and pig fontal cortex membranes. Competition experiments with [125I]BE 2254 using 17 agonists and antagonists showed monophasic and steep curves in human and pig frontal cortex membranes. The pharmacological profile of these sites is typical of alpha 1-adrenoceptors. In competition experiments with [3H]ketanserin, most of the tested compounds displayed shallow or biphasic curves. In particular, alpha 1-adrenoceptor-selective antagonists (prazosin, WB 4101, BE 2254...) displaced with nanomolar affinity about 15 and 40% of the specific [3H]ketanserin binding in human and pig frontal cortex membranes, respectively. The minor component of [3H]ketanserin binding correlated highly significantly with [125I]BE 2254 binding in both membrane preparations. The major component of [3H]ketanserin binding to pig and human frontal cortex membranes correlated significantly with [3H]ketanserin binding in rat brain cortex membranes (which is essentially to 5-HT2 receptors). The present data demonstrate that [3H]ketanserin in nanomolar concentrations binds significantly to alpha 1-adrenoceptors in human and pig frontal cortex membranes; this suggests a rather limited degree of selectivity of ketanserin for 5-HT2 receptors in pig and human tissues.     

Detection of circulating human platelet fragments by using monoclonal antibodies against platelet glycoprotein IIb-IIIa complex

A radioimmunoassay (RIA) for the detection of platelets and platelet fragments was developed. A sandwich of two monoclonal antibodies directed against the platelet-specific glycoprotein complex IIb-IIIa (GP IIb-IIIa) was used in this assay. A discontinuous 7.5-20% (v/v) albumin gradient was applied to separate platelets and their fragments of various sizes. In platelet suspensions fractionated in this way, we observed that particles smaller than normal platelets still carried the GP IIb-IIIa antigens. This procedure enabled us to detect platelet-derived particles in platelet-rich plasma from thrombocytopenic patients.     

Severe Electrolyte Disturbances in Lethal Subclavian Catheter Dialysis

Abstract: Syncope, irreversible shock, and respiratory and circulatory arrest developed in a 54-year-old diabetic man chronically dialyzed with a subclavian catheter (SC) minutes after the end of a dialysis session. Resuscitation attempts remained unsuccessful. During the resuscitation attempt, a blood analysis showed severe hyponatremia, acidosis, and hypochloremia. Respiratory and cardiac arrest developed during dialysis in a 64-year-old woman on chronic SC dialysis. Resuscitation was unsuccessful; chloremia levels were 79 mEq/L, and calcemia levels were 20 mg%. Both patients were dialyzed with a standard dialysate solution. The reasons for the electrolyte disturbances could not be explained technically. The autopsy showed myocardial perforation by the SC and accumulation in the pericardium of the fluids administered during the resuscitation attempt (e.g., glucose 5%, bicarbonate, Ca gluconate, human albumines), thus explaining the erroneous electrolyte results. The reason for the perforation was a too-rigid central femoral vein catheter, erroneously labeled a subclavian catheter by the supplying firm. Because of a syndrome of progressive vena subcla-via and vena cava sclerosis with insufficient arterial phase flow and venous-phase bleeding around the puncture site during single-needle dialysis, the original SC had to be replaced by a longer one with the tip located in the atrium (this SC was actually a femoral catheter). Analysis of the fluid aspirated through the SC can determine the diagnosis in sudden death of SC dialysis patients.     

Alterations in the cortical thymic epithelium of rats after in vivo exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD): an (immuno)histological study.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) induces thymic atrophy in rats. The present study was initiated to provide (immuno)histological data on the mechanism of action. Juvenile male Wistar rats were orally intubated once with 50 or 150 micrograms/kg TCDD. They were euthanized 4 or 10 days thereafter, or were allowed to stay alive until Day 20 or 26. Growth retardation occurred rapidly in all TCDD-treated animals. Lethality was demonstrated within 20-21 days after administration. At Days 4 and 10 after intubation, thymic atrophy was shown by reduction of thymic weight and cortex/medulla ratio. Staining patterns for T-cell markers in the atrophic thymuses coincided with the reduction of cortical areas. There was no evidence indicating that the effects were indirectly caused by stress. TCDD-induced thymic atrophy persisted until Day 26 after administration. Immunohistochemical analysis revealed prominent changes in the cortical thymic epithelium at the 150-micrograms/kg dose level. First, in the cortex epithelial cell aggregates were observed both at Day 4 and at Day 10 after administration. Apparently, the architecture of the epithelium had changed in these animals. Second, at 10 days after administration epithelial cells were found with the simultaneous expression of markers that in the normal uninvoluted thymus only occur either in the subcapsular/medullary area or in the cortex. This phenotype points to an unusual stage of differentiation. We conclude that TCDD exposure affects the cortical epithelium of the rat thymus at a high dose level. Apparently, it disturbs the epithelial network and interfers with the differentiation of epithelial cells.     

Keratin and vimentin distribution patterns in the epithelial structures of the cannie anal region

The intermediate filament labeling pattern of the epithelial structures of the canine anal region was studied with different polypeptide specific keratin monoclonal antibodies (MoAbs) and with a monoclonal and polyclonal vimentin antibody. The epithelial structures in this region could be discriminated and characterized by differences in their keratin staining pattern. The basal cells in the different epithelial structures showed a similar staining pattern characterized by reactivity with MoAbs staining keratins 5, 8, 14, and 17. Columnar epithelial cells showed a completely different phenotype mostly characterized by reactivity with MoAbs staining keratins 7, 5, 8, 18, and 19. A restricted number of differentiated perianal gland cells showed perinuclear vimentin staining. Myoepithelial cells did not stain for vimentin, but, as other basal cells, were positive for MoAbs staining keratins 5, 8, 14, and 17.© Willey-Liss, Inc.     

Conversion from Cyclosporine to Tacrolimus Improves Quality-of-Life Indices, Renal Graft Function and Cardiovascular Risk Profile

Long-term use of cyclosporine after renal transplantation results in nephrotoxicity and an increased cardiovascular risk profile. Tacrolimus may be more favorable in this respect. In this randomized controlled study in 124 renal transplant patients, the effects of conversion from cyclosporine to tacrolimus on renal function, cardiovascular risk factors, and perceived side-effects were investigated after a follow-up of 2 years. After conversion from cyclosporine to tacrolimus renal function remained stable, whereas continuation of cyclosporine was accompanied by a rise in serum creatinine from 142 +/- 48 micromol/L to 157 +/- 62 micromol/L (p < 0.05 comparing both groups). Conversion to tacrolimus resulted in a sustained reduction in systolic and diastolic blood pressure, and a sustained improvement in the serum lipid profile, leading to a reduction in the Framingham risk score from 5.7 +/- 4.3 to 4.8 +/- 5.3 (p < 0.05). Finally, conversion to tacrolimus resulted in decreased scores for occurrence of and distress due to side-effects. In conclusion, conversion from cyclosporine to tacrolimus in stable renal transplant patients is beneficial with respect to renal function, cardiovascular risk profile, and side-effects. Therefore, for most renal transplant patients tacrolimus will be the drug of choice when long-term treatment with a calcineurin inhibitor is indicated.     

The gap between legal rules and practice in advertising non-registered pharmaceutical products : A new method of analysis

The market of non-registered pharmaceutical products is growing fast in number and overall costs, not only in the Netherlands, but also in other European countries. These products often give the impression that the consumer may expect 'an effect as from a drug'. Legally, there is a clear distinction between 'drugs' and 'commodities' in the Netherlands; the question is whether legislation and practice concur. In an investigation we analysed texts of advertisements for non-registered pharmaceutical products published in a popular magazine. A method was developed, based on the legal definition of a drug and jurisprudence, to determine in a qualitative and quantitative way the application of medicinal claims. It transpired that in 65% of the analysed advertisements explicit or implicit claims were made. These products should therefore be subject to drugs legislation. Thus, in the Netherlands there is a gap between legislation and practice in advertising non-registered pharmaceutical products.