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Colchicine analogues: effect on amyloidogenesis in a murine model and, in vitro, on polymorphonuclear leukocytes.

Colchicine has been used in diverse clinical settings such as gout, familial Mediterranean fever, liver cirrhosis, Behcet's disease and pericarditis. It also has an antimitotic potential hitherto unexplored due to its narrow therapeutic toxic ratio. The aim of the present study was to compare the effectiveness and the toxicity of colchicine and three analogues: thiocolchicine, 2,3 dimethyl-colchicine and 3-dimethylthiocolchicine in the blockage of amyloid synthesis in a murine model. 3-demethylthiocolchicine was equipotent to colchicine in the blockage of casein induced amyloidogenesis. However, it was markedly less toxic (LD50 11.3 mg kg-1 vs. 1.6 mg kg-1). Thiocolchicine was toxic (LD50 1.0 mg kg-1) and 2,3 didemethyl-colchicine was far less effective. The effect of 3-dimethylthiocolchicine on polymorphonuclear leukocytes was then compared to colchicine. The effect of this analogue on inhibition of chemotaxis was equivalent to that of colchicine whereas the latter was superior to the analogue in the suppression of phagocytosis (by a ratio of 2:1) and in the inhibition of bactericidal activity (by a ratio of 10:1). Since in therapeutic concentrations the only detectable effect of colchicine on PMNs is inhibition of chemotaxis, our data may point to 3-demethylthiocolchicine as an optional, perhaps superior alternative to colchicine for some of its therapeutic indications.

Amyloid↗

Requirement of a colchicine-sensitive component of the cytoskeleton for acetylcholine receptor recovery.

1. The effect of colchicine treatment on acetylcholine receptor function was examined in potassium depolarized, voltage-clamped snake twitch fibre endplates. Receptor function was assessed by analysis of miniature endplate currents (m.e.p.c.) as well as acetylcholine (ACh)-induced single channel currents. 2. Pretreatment of snake muscle fibres with colchicine (10 microM to 100 microM) for 16-18 h had no effect on m.e.p.c. amplitude or decay rates. At higher concentrations (1 mM), there was a slight decrease in the average m.e.p.c. amplitude. 3. Colchicine produced a concentration-dependent decrease in the extent of m.e.p.c. amplitude recovery following a 10 min exposure to 540 microM carbachol. Exposure of 100 microM colchicine-treated preparations to 0.5 microM staurosporine further reduced the extent of m.e.p.c. amplitude recovery following carbachol exposure. 4. The decrease in m.e.p.c. amplitude following carbachol exposure was not due to a shift in the m.e.p.c. reversal potential. In addition, the distribution of m.e.p.c. amplitudes remained unimodal in both control and colchicine (100 microM)-treated preparations following carbachol exposure. 5. In addition to the normal, large conductance (approximately 48 pS) ACh-activated channels, a population of small conductance (approximately 29 pS) channels was observed in colchicine-treated preparations following exposure to carbachol. In preparations treated with both colchicine and staurosporine and then exposed to carbachol, the conductance of these small channels was identical to that of colchicine or staurosporine alone. 6. We suggest that prolonged exposure of snake twitch fibre endplates to agonist results in the activation and desensitization of ACh receptors. Furthermore, we propose that for a subpopulation of the inactivated receptors, restoration of function requires both the integrity of a subsynaptic cytoskeletal component and phosphorylation by a staurosporine-sensitive protein kinase. One plausible mechanism is that some receptors become destabilized in the membrane and phosphorylation of a cytoskeletal component, whose distribution may depend on an intact microtubular system, is required to re-anchor these receptors. If this anchoring process is inhibited either by disruption of the cytoskeleton with colchicine, or inhibition of the kinase by staurosporine, these receptors remain activatable, but have a reduced conductance.

Alkaloids↗

Electrophysiological analysis of colchicine-induced supersensitivity in the rat vas deferens.

1. The supersensitivity in smooth muscle of the rat vas deferens induced by local application of colchicine to the hypogastric plexus was investigated electrophysiologically. 2. Spontaneous junction potentials could be detected in nearly all of the impaled cells, but they occurred with lesser frequency and smaller amplitude in the colchicine-treated rat vas deferens than in the control tissue. However, this clearly demonstrated that, although attenuated, neuromuscular transmission still persisted after colchicine treatment. 3. The mean resting potential of smooth muscle cells of the colchicine-treated vas deferens (58.2 +/- 0.3 mV, n - 146) was not significantly different from that of the cells of the contralateral control tissue (58.1 +/- 0.2 mV, n = 130). 4. The threshold potential for action potentials induced by either nerve stimulation or extracellular current application was more negative by approximately 10 mV in the colchicine-treated vas deferens in comparison with the control tissue. 5. Externally applied current pulses of long duration failed to produce electrotonic potentials in any smooth muscle cell of normally innervated rat vas deferens which was located more than 0.5 mm from the partition electrode. In the colchicine-treated tissue, however, electrotonic potentials in the smooth muscle cell could be detected for a distance up to 2.5 mm from the partition electrode. The space constant in the colchicine-treated tissue was determined to be 0.79 +/- 0.02 mm (n = 10). 6. It is concluded that (i) the magnitude of depolarization from resting to threshold potentials in the colchicine-treated vas deferens was significantly smaller than that in the contralateral control tissue and (ii) that the current spread in a longitudinal direction was improved following colchicine treatment.

Animals↗

Effect of colchicine on urinary phosphate and regulation by parathyroid hormone.

The possible role of cytoplasmic microtubules in the renal handling of phosphate and its regulation by parathyroid hormone (PTH) was evaluated with colchicine, a microtubule-disrupting agent. Colchicine-treated rats were thyroparathyroidectomized (TPTX) and subsequently infused with PTH. Treatment with a total dose of 1 mg colchicine had no effect on glomerular filtration rate or fractional excretions of sodium and potassium. Fractional excretion of phosphate in colchicine-treated TPTX rats was significantly higher compared with TPTX controls. After PTH infusion, control rats responded with increases in fractional excretion of phosphate and urinary cyclic AMP but colchicine-treated rats had variable and insignificant changes in both parameters. Fractional excretion of sodium and potassium did not change significantly after PTH. Renal cortical activities of cyclic AMP phosphodiesterase, soluble alkaline phosphatase, cytochrome oxidase, leucine aminopeptidase, or basal adenylate cyclase were not significantly affected by colchicine treatment. On the other hand, stimulation of adenylate cyclase by a submaximal dose of PTH was markedly decreased in colchicine-treated rats, and the activity of membrane-bound alkaline phosphatase was also significantly decreased. The binding of radioactive colchicine in renal cortical extracts from rats treated with colchicine was significantly diminished. These results suggest that disruption of cytoplasmic microtubules in renal cortical cells interferes with phosphate transport and its regulation by PTH.

Alkaline Phosphatase↗

Colchicine inhibits arachidonate release and 5-lipoxygenase action in alveolar macrophages.

Although colchicine is known to inhibit leukotriene synthesis in neutrophils, its effect on other aspects of arachidonic acid (AA) metabolism as well as its mechanism of action are unknown. To address these questions, we investigated the effects of colchicine on resident rat alveolar macrophages (AM), cells that generate a variety of lipoxygenase and cyclooxygenase products after stimulation. Pretreatment of AM with 10 microM colchicine for 1 h dramatically inhibited the synthesis of all 5-lipoxygenase (5-LO) metabolites from endogenous AA in ionophore A-23187-stimulated cells. In addition, colchicine inhibited the total release of AA as well as prostanoids to a lesser extent. Similar effects were observed with the other microtubule-disruptive agents nocodazole and vinblastine, and 5-LO product formation stimulated by the particulate agonist zymosan was inhibited as well. A selective inhibitory effect of colchicine on the 5-LO pathway was demonstrated by monitoring the synthesis of 5-LO products from exogenously supplied AA. Cell-free enzyme assays showed that this effect was not through a direct inhibition of the 5-LO enzyme. Moreover, colchicine did not affect the translocation of 5-LO to the nuclear envelope. We next evaluated the effect of colchicine on the levels of the two 5-LO cofactors, ATP and Ca2+. Although colchicine did not affect ATP levels, it did abrogate the ionophore-induced increase in intracellular Ca2+ concentration; the inhibitory effect of colchicine on 5-LO metabolism in AM was partially overcome by stimulation with higher doses of A-23187. We conclude that microtubular disruption inhibits agonist-induced increase in intracellular Ca2+ concentration, with multiple consequences for AA metabolism. These include a reduction in the liberation of AA from membrane phospholipids as well as the selective inhibition of processing of AA by 5-LO.

Adenosine Triphosphate↗

Colchicine alters the quantitative and qualitative display of selectins on endothelial cells and neutrophils.

Since colchicine-sensitive microtubules regulate the expression and topography of surface glycoproteins on a variety of cells, we sought evidence that colchicine interferes with neutrophil-endothelial interactions by altering the number and/or distribution of selectins on endothelial cells and neutrophils. Extremely low, prophylactic, concentrations of colchicine (IC50 = 3 nM) eliminated the E-selectin-mediated increment in endothelial adhesiveness for neutrophils in response to IL-1 (P < 0.001) or TNF alpha (P < 0.001) by changing the distribution, but not the number, of E-selectin molecules on the surface of the endothelial cells. Colchicine inhibited stimulated endothelial adhesiveness via its effects on microtubules since vinblastine, an agent which perturbs microtubule function by other mechanisms, diminished adhesiveness whereas the photoinactivated colchicine derivative gamma-lumicolchicine was inactive. Colchicine had no effect on cell viability. At higher, therapeutic, concentrations colchicine (IC50 = 300 nM, P < 0.001) also diminished the expression of L-selectin on the surface of neutrophils (but not lymphocytes) without affecting expression of the beta 2-integrin CD11b/CD18. In confirmation, L-selectin expression was strikingly reduced (relative to CD11b/CD18 expression) on neutrophils from two individuals who had ingested therapeutic doses of colchicine. These results suggest that colchicine may exert its prophylactic effects on cytokine-provoked inflammation by diminishing the qualitative expression of E-selectin on endothelium, and its therapeutic effects by diminishing the quantitative expression of L-selectin on neutrophils.

Animals↗

Colchicine protects mice from the lethal effect of an agonistic anti-Fas antibody.

The aim of this study was to determine whether colchicine, which has been reported to protect against various hepatotoxic insults, influences the susceptibility of mice to the agonistic anti-Fas antibody, Jo2. All mice that were pretreated with colchicine (2 mg/kg) survived the lethal challenge of intraperitoneal administration of 10 microg of Jo2, whereas all control mice pretreated with gamma-lumicolchicine succumbed to the challenge. Twelve micrograms of Jo2 killed less than half of colchicine-pretreated mice and its lethal effects were delayed relative to control mice, which all died within 8 hours. Other microtubule-disrupting agents such as Taxol, vinblastine, and nocodazole also improved the survival of mice treated with the lethal dose of Jo2. Histologic examination showed that colchicine protected against Jo2-induced fulminant liver injury, and TUNEL assay demonstrated that colchicine protected against massive apoptosis of hepatocytes. Hepatocytes isolated from colchicine-pretreated mice exhibited decreased susceptibility to Jo2-induced apoptosis. In addition, colchicine pretreatment reduced surface expression of Fas and decreased Jo2- and TNF-alpha-induced apoptosis of cultured hepatocytes in the presence of actinomycin D, but did not affect the susceptibility of cultured sinusoidal endothelial cells to Jo2-induced apoptosis. Remarkably, Fas and TNF receptor-1 mRNA and intracellular protein levels increased after colchicine treatment, indicating that colchicine protects against death ligand-induced apoptosis in the liver by decreasing death-receptor targeting to the cell surface.

Animals↗

Intraneural colchicine inhibition of adenoviral and adeno-associated viral vector remote spinal cord gene delivery.

OBJECTIVE: The mechanism of remote viral gene delivery to the spinal cord is unknown. The present experiment demonstrates that intraneural injection of colchicine is capable of inhibiting remote delivery of both adenoviral and adeno-associated viral (AAV) vectors, implicating axonal transport in this process. METHODS: The right sciatic nerves of adult Sprague-Dawley rats were injected with phosphate-buffered saline (PBS) (n = 5) or 10 (n = 7) or 100 (n = 4) microg colchicine. Two days later, the nerves of all animals were initially injected with 1.2 x 10(7) plaque-forming units of Ad5RSVntLac-Z. Two separate groups were injected concurrently with vector and PBS (n = 5) or 10 microg colchicine (n = 5). In a second experiment, the right sciatic nerves of CD1 mice were preinjected with PBS (n = 6) or 10 microg colchicine (n = 5). Two days later, the nerves were injected with rAAVCAG-EGFPwpre (an adeno-associated vector carrying the green fluorescent protein gene). In both experiments, sciatic nerves and spinal cords were removed and analyzed for gene expression. RESULTS: Sciatic nerve vector injection resulted in expression in both the nerve injection site and neuronal cell bodies located predominantly in the ipsilateral ventral horn. Analysis of variance revealed a significant treatment effect for 10 and 100 microg intraneural colchicine with inhibition of remote adenoviral delivery at 10 microg and blockade of remote delivery at 100 microg (P < 0.001). Colchicine injection concurrent with and before vector injection had similar inhibitory effects. Two-way analysis of variance revealed significant colchicine inhibition of remote delivery in both adenovirus- and AAV-injected animals (P < 0.003) but no dose-by-vector interaction, suggesting that both vectors are equally inhibited by colchicine. CONCLUSION: Colchicine inhibits remote spinal cord delivery of adeno-associated and adenoviral vectors in a dose-dependent manner, suggesting that remote delivery is dependent on retrograde axonal transport.

Adenovirus E1 Proteins↗

The effect of colchicine on fibrillar material in wheat meiocytes.

Wheat meiocytes contain intranuclear bundles of microfibres at stages from pre-meiotic mitosis until zygotene. This includes early pre-meiotic interphase, the stage when colchicine induces univalents at subsequent metaphase I. This paper reports the effect of colchicine on the structure and distribution of such fibrillar material. Many normal-looking bundles of intranuclear fibrillar material formed after prolonged colchicine treatment (up to 5 days) which totally suppressed microtubule assembly in meiocytes. Thus, fibrillar material is unlikely to comprise tubulin. However, the formation of intranuclear fibrillar material was retarded in colchicine-treated meiocytes, and fibrillar material was absent during the colchicine-sensitive stage for univalency. The occurrence of cytoplasmic fibrillar material was delayed and greatly increased in colchicine-treated meiocytes compared with controls. A novel curved form of fibrillar material was seen in colchicine-treated meiocytes. It is concluded that colchicine had significant effects on the assembly and distribution of fibrillar material. These results are, therefore, compatible with the possibility that colchicine causes univalency in wheat via its effects on fibrillar material.

Cell Cycle↗

Acute myopathy in a patient with concomitant use of pravastatin and colchicine.

OBJECTIVE: To report a case of acute myopathy after concomitant use of colchicine and pravastatin. CASE SUMMARY: A 65-year-old woman was admitted to the hospital with an acute episode of gout. She had been taking pravastatin 20 mg once daily for 6 years. On admission, blood urea nitrogen and serum creatinine levels were 48 mg/dL and 1.3 mg/dL, respectively. Colchicine 1.5 mg/day was added to the treatment regimen, but 20 days after the initiation of colchicine therapy, symmetrical proximal muscle weakness developed in the woman's legs. Physical examination, laboratory findings, and electromyelogram findings suggested myopathy. The Naranjo probability scale indicated a probable relationship between myopathy and combined therapy. Seven days after discontinuation of colchicine and pravastatin, the patient's weakness improved and enzyme levels returned to normal. Colchicine was restarted at 1.0 mg/day 5 days later; no myopathy occurred. DISCUSSION: Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) and colchicine are known to cause myopathy. Most of the statins and colchicine are biotransformed in the liver primarily by the CYP3A4 system, which may increase the risk of myopathy when concurrent therapy is used. However, pravastatin is not primarily metabolized by cytochrome P450 isoenzymes. The cause of myopathy in our patient may be related to the interaction of colchicine and pravastatin via P-glycoprotein. In addition, the presence of mild renal dysfunction could have contributed to the development of myopathy. CONCLUSIONS: We suggest that clinicians be aware that neuromuscular toxicity can occur in patients with mild renal dysfunction with combined use of colchicine and pravastatin.

Acute Disease↗

Effects of colchicine on IgE-mediated early and late airway reactions.

BACKGROUND: The pathogenesis of bronchial asthma is thought to involve elements of both acute and chronic inflammation. Hence, there is growing interest in the potential of immunomodulatory drugs in asthma therapy. This study examines the effects of the anti-inflammatory compound colchicine on early and late allergen-induced, IgE-mediated airway reactions. METHODS: Nine mildly allergic asthmatic subjects were evaluated in a single-blind, two-way crossover study designed to examine the effects of colchicine and placebo on early and late airway reactions to ragweed allergen and related changes in nonspecific responsiveness to methacholine. RESULTS: Compared with placebo, colchicine provided 19% (p = 0.036) and 40% (p = 0.004) inhibition of early and late airway reactions to allergen, respectively. Allergen-induced increases in methacholine responsiveness were observed with both types of treatment, although there was a trend toward a smaller increase after administration of colchicine (p = 0.13). We also found that methacholine responsiveness per se was not directly altered by colchicine (n = 7). In 6 subjects, we found suppression of neutrophil leukotriene B4 generation after colchicine treatment, suggesting that the colchicine dose (0.6 mg twice daily) was sufficient to produce an anti-inflammatory effect. Further in vitro studies using purified human lung tissue mast cells failed to demonstrate inhibition of mediator release at concentrations corresponding to achievable tissue or blood levels during the in vivo trial. CONCLUSION: Colchicine partially inhibits IgE-mediated early and late airway reactions at conventional clinical doses. This inhibitory effect may be mediated via suppression of some cell species other than the lung tissue mast cell. Controlled studies to examine the benefits of colchicine in clinically evidenced asthma are warranted.

Adult↗

Effects of colchicine on amoeboid microglial cells in the postnatal rat brain.

The present study was conducted to examine the response of amoeboid microglial cells in the postnatal rat brain to colchicine administration. One-day-old postnatal rats were given intraperitoneal injections of colchicine and sacrificed at 7, 14 and 21 days of age. In rats killed at 7 days age, the number of OX-42, OX-18 and ED1 positive amoeboid microglial cells was considerably reduced when compared with the control rats. At 14 and 21 days, the number of cells immunoreactive with the above antibodies was comparable to that of the control rats. The intensity of the immunoreaction with the various antibodies was also comparable in colchicine injected and control rats. When rhodamine isothiocyanate (RhIC) was administered, amoeboid microglial cells emitted a bright fluorescence in control rats as well as in colchicine-injected rats, although in the latter, the number of RhIC labelled cells was considerably reduced. With the antibody bromodeoxyuridine a large number of stained cells were observed in the control rats. On the other hand, occasional labelled cells were recognized in colchicine-injected rats. Apoptotic amoeboid microglial cells were observed in 4-day-old colchicine-injected rats. At the electron microscopic level, amoeboid microglial cells in colchicine-injected rats killed at 7 days of age showed a large number of phagosomes in their cytoplasm compared with the corresponding control rats. At 14 and 21 days, in colchicine-injected and control rats, amoeboid microglial cells did not display any noticeable differences. It is concluded from the present study that colchicine suppresses the number of amoeboid microglial cells, and that this may be attributed to the antimitotic effect of the drug as well as apoptosis induced by it; the phagocytic activity, however, was not affected. The cells returned to their normal population and morphological features once the drug was discontinued, indicating the reversible nature of the drug effect.

Animals↗

Moderate protection of renal function and reduction of fibrosis by colchicine in a model of anti-GBM disease in the rabbit.

A rabbit model of renal glomerulosclerosis induced by anti-glomerular basement membrane antibody was used to determine whether colchicine would protect renal function and reduce fibrosis. Initial studies established the time course of renal function changes and fibrosis. Colchicine at a dose of 0.02 to 0.04 mg/kg per day injected ip was begun at day 4 when injury had been initiated, and the experiment was ended at day 21 when fibrotic changes were established. Colchicine significantly reduced the rise in serum creatinine (serum creatinine = 2.7 +/- 0.3 mg% in vehicle-treated animals versus 1.8 +/- 0.1 mg% in colchicine-treated animals) and interstitial fibrosis (fibrosis score = 2.6 +/- 0.2 in vehicle-treated versus 1.5 +/- 0.2 in colchicine-treated animals). Colchicine treatment did not significantly affect weight, anti-guinea pig immunoglobulin level, % fibrocellular crescents formed, hydroxyproline per gram (dry weight) in tissue, or urine protein: creatine ratio. Regression analysis was performed to examine the interrelationships between variables for all animals and the effect of colchicine on pairs of variables. No clear-cut site of colchicine action could be identified. These data show that colchicine, in doses that could be used in humans, protected renal function by about 25% and reduced interstitial fibrosis in a model of severe crescentic nephritis.

Animals↗

Colchicine allows prolonged survival of highly reactive renal allograft in the rat.

Colchicine, with its immunosuppressive properties, has been used with beneficial effects in autoimmune diseases. Whether colchicine, by virtue of the above properties, could attenuate the process of kidney allograft rejection in the rat is investigated in this report. Untreated Lewis rats (N = 6) given an incompatible kidney allograft from Brown-Norway rats rejected the graft within 12 days. Colchicine at a daily ip dose of 40 (N = 6) or 10 (N = 4) micrograms/kg promoted long-term survival (> 170 days) of major histocompatibility complex-incompatible kidney grafts. Animals (N = 4) given 4 micrograms of colchicine per kilogram had a graft failure within 10 days. Experiments have also been performed to evaluate the effect of colchicine withdrawal at different time intervals from transplantation on subsequent allograft survival. Colchicine (40 micrograms/kg per day ip) was given for 12, 6, or 1 mo or for 15 days to an additional four groups of six animals each without any other immunosuppressants. The withdrawal of colchicine did confer long-term inhibition of the immune system in animals treated for at least 1 mo, as documented by a graft survival of more than 80 days. By contrast, those animals who discontinued colchicine after only 15 days of treatment had graft rejection within the next 8 days. Mixed lymphocyte culture experiments showed a significant (P < 0.01) reduction of the proliferation of peripheral blood lymphocytes taken from all groups of animals 30 days after colchicine withdrawal when challenged with Brown-Norway lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Biliary excretion of colchicine.

After intravenous administration of 3H-colchicine (0.2 mg/kg) to rats, 68 percent was excreted in the feces in 48 hours suggesting bile might be the major route of excretion for colchicine. Rats with cannulated bile ducts excreted 50 percent of a 2 mg/kg dose into the bile within 2 hours; half of this was colchicine, and the rest was desmethylcolchicine and more polar metabolites. Colchicine was excreted into the bile of the rat against a bile/plasma concentration gradient of 800 which resulted from a liver/plasma ratio of 15 and a bile/liver ratio of 60. The biliary excretion of colchicine varied widely among the hamster, dog and rabbit. Of the administered colchicine, 32, 20 and 16 percent were excreted by the hamster, dog and rabbit, respectively, within 2 hours. There was also a species difference in the percentage of the radioactivity present in bile as the parent drug. In the hamster, dog and rabbit, the percentage of radioactivity excreted into the bile as colchicine was 45, 34 and 72 percent, respectively. These species excreted colchicine into the bile against a bile/plasma gradient ranging from 19 to 870. Partition of these gradients between liver/plasma and bile/liver ratios demonstrated that both ratios were greater than one, suggesting that colchicine is excreted by an active process. The liver/bile gradient was always the larger of the two ratios.

Animals↗

[Recurrent aphthous stomatitis: treatment with colchicine. An open trial of 54 cases].

INTRODUCTION: Colchicine is a treatment used for aphthous stomatitis but its efficacy has never been proved. We report the results of an open trial of 54 patients treated with colchicine for aphthous stomatitis. The aim of our study was to assess the long and short term efficacy and tolerance of this molecule in this disease. PATIENTS AND METHODS: The case reports of 64 patients presenting with severe, recurrent aphthous stomatitis treated with colchicine between 1986 and 2000 were analyzed retrospectively. Only immunocompetent patients exhibiting idiopathic aphthous stomatitis or Behçet's disease were included. Ten patients were excluded: 4 cases of Behçet's disease treated with colchicine and systemic corticosteroids, 4 cases of aphthous stomatitis secondary to a hematological cause and 2 patients who were lost to follow-up after 3 month's treatment. Colchicine was prescribed at a dose of 1 to 1.5 mg/d for at least 3 months. All the patients were assessed after 3 month's treatment and all were contacted by phone in May 2000. Our end-point criteria were: the frequency and duration of the episodes, intensity of pain and impact on the quality of life of the patients. RESULTS: Fifty-four patients were included: 39 women (mean age=44 +/- 16.8) and 15 men (mean age=49 +/- 13.5). The disease had progressed for a mean of 11.6 +/- 13.5 years. After 3 month's treatment, 12 patients (22 p. 100) no longer had aphta and were in complete remission, 22 patients (41 p. 100) were significantly improved, since the frequency and duration of the lesions had decreased by at least 50 p. 100 and the latter were no longer painful. Treatment failed or tolerance was poor in 20 patients (37 p. 100). Patients were monitored and assessed for a mean of 4.7 years (range: 6 months to 13 years). Six patients were lost to follow-up. Three patients (6 p. 100) were considered as cured, since they were still in complete remission after suspension of colchicine respectively 6, 24 and 72 months later. Fifteen patients (31 p. 100) had still improved. Among the latter, 10 continued colchicine for a mean of 27 months, and 5 patients stopped treatment, which they considered tedious, after a mean of 16 months. These 15 patients noted a significant reduction in the frequency and duration of the lesions. Moreover, the subjective end-point criteria had improved significantly for them not to wish to change treatment. Thirty patients (63 p. 100) were not improved by the treatment. Some benign adverse events were noted in 10 patients (18.5 p. 100) and led to suspension of treatment in 4 cases. DISCUSSION: This study, which is the first in size (n=54) and duration of follow-up (4.7 years), showed that colchicine is an efficient preventive treatment of severe aphthous stomatitis for 63 p. 100 of patients after 3 month's treatment and that this improvement was lasting in 37 p. 100 of them. Colchicine should therefore be proposed in first intention in severe recurrent aphthous stomatitis, since it is effective, well tolerated and easy to use.

Adult↗

Effect of cyclosporine on colchicine secretion by the kidney multidrug transporter studied in vivo.

The multidrug resistance (MDR) transport protein is a normal constituent of proximal renal tubules although its function has not been defined in vivo. We find that colchicine, an MDR substrate, is secreted into urine by a process which is distinct from the organic cation transporter responsible for tetraethylammonium and N-methylnicotinamide secretion. Cyclosporine (CsA), which reverses MDR in vitro presumably by inhibiting the MDR transporter, inhibits colchicine renal secretion but does not inhibit the net secretion of the organic cation, ranitidine, or the organic anion, p-aminohippurate. After CsA (2 mg/kg i.v.), colchicine renal clearance decreased from 6.23 +/- 0.46 to 3.58 +/- 0.31 ml/min.kg (P less than .05), glomerular filtration rate was unchanged (4.21 +/- 0.08 and 3.88 +/- 0.17 ml/min.kg, before and after CsA, respectively; P = .09) and colchicine secretory ratio decreased from 1.48 +/- 0.11 to 0.92 +/- 0.07 (P less than .05). Cremophor (CsA vehicle) increased colchicine renal clearance (6.77 +/- 0.29 to 7.7 +/- 0.3 ml/min.kg, P less than .05) and colchicine secretory ratio (1.425 +/- 0.071 to 1.621 +/- 0.061, P less than .05). The inhibition of colchicine secretion was long-lived lasting at least 30 hr after CsA. Thus, colchicine is actively secreted into urine by the multidrug transporter in vivo. CsA profoundly inhibits colchicine secretion into urine while having no effect on the secretion of the organic cation ranitidine or the organic anion p-aminohippurate.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Long-term follow-up of patients with primary biliary cirrhosis on colchicine therapy.

We followed up a group of patients with primary biliary cirrhosis who participated in a 4-yr prospective, double-blind controlled trial of colchicine therapy for 4 additional years. All were placed on open label colchicine (0.6 mg twice daily) after the trial was concluded. Of the original group of 28 patients treated with colchicine, 8 died and 5 received transplants (3 of the 5 died). Of the original placebo control group eight patients died and six received transplants (1 of the 6 died). Surviving patients on long-term colchicine therapy (mean period = 8.1 yr, range = 5.3 to 9.1) showed reduction of mean serum alkaline phosphatase from 5.1 times the upper limit of normal values to 1.9 times (p less than 0.01). Mean ALT fell from 1.8 to 1.2 times the upper limit of normal (p = 0.05), and mean serum total bilirubin remained stable (1.6 mg/dl vs. 1.5 mg/dl). Major complications of cirrhosis developed in four patients in the colchicine group and five patients in the original control group. The only side effect of colchicine was diarrhea, which was noted in three patients. The diarrhea resolved with reduction in the dose of colchicine. Colchicine is a safe and inexpensive drug for the long-term treatment of primary biliary cirrhosis. The biochemical parameters of disease activity (alkaline phosphatase and ALT) remain improved after long-term follow-up, and bilirubin values remain stable. However, complications of cirrhosis, deaths and transplantations were not prevented. The clinical usefulness of colchicine in the treatment of primary biliary cirrhosis seems to be limited.

Alanine Transaminase↗