Prolongation of metallothionein induction combats Aß and α-synuclein toxicity in aged transgenic Caenorhabditis elegans

Neurodegenerative disorders (ND) like Alzheimer's (AD), Parkinson's (PD), Huntington's or Prion diseases share similar pathological features. They are all age dependent and are often associated with disruptions in analogous metabolic processes such as protein aggregation and oxidative stress, both of which involve metal ions like copper, manganese and iron. Bush and Tanzi proposed 2008 in the 'metal hypothesis of Alzheimer's disease' that a breakdown in metal homeostasis is the main cause of NDs, and drugs restoring metal homeostasis are promising novel therapeutic strategies. We report here that metallothionein (MT), an endogenous metal detoxifying protein, is increased in young amyloid ß (Aß) expressing Caenorhabditis elegans, whereas it is not in wild type strains. Further MT induction collapsed in 8 days old transgenic worms, indicating the age dependency of disease outbreak, and sharing intriguing parallels to diminished MT levels in human brains of AD. A medium throughput screening assay method was established to search for compounds increasing the MT level. Compounds known to induce MT release like progesterone, ZnSO4, quercetin, dexamethasone and apomorphine were active in models of AD and PD. Thioflavin T, clioquinol and emodin are promising leads in AD and PD research, whose mode of action has not been fully established yet. In this study, we could show that the reduction of Aß and α-synuclein toxicity in transgenic C. elegans models correlated with the prolongation of MT induction time and that knockdown of MT with RNA interference resulted in a loss of bioactivity.

Development of a copper-clioquinol formulation suitable for intravenous use

Clioquinol (CQ) is an FDA-approved topical antifungal agent known to kill cancer cells. This facilitated the initiation of clinical trials in patients with refractory hematologic malignancies. These repurposing efforts were not successful; this was likely due to low intracellular levels of the drug owing to poor absorption and rapid metabolism upon oral administration. CQ forms a sparingly soluble copper complex (Cu(CQ)2) that exhibits enhanced anticancer activity in some cell lines. We have utilized a novel method to synthesize Cu(CQ)2 inside liposomes, an approach that maintains the complex suspended in solution and in a format suitable for intravenous administration. The complex was prepared inside 100-nm liposomes composed of 1,2-distearoyl-sn-glycero-3-phosphocholine/cholesterol (55:45). The therapeutic activity of the resultant formulation was evaluated in two subcutaneous tumor models (glioblastoma and ovarian cancers) but was not active. We also assessed the ability of the Cu(CQ)2 formulation to increase copper delivery to cancer cells in vitro and its potential to be used in combination with disulfiram (DSF). The results suggested that addition of Cu(CQ)2 enhanced cellular copper levels and the activity of DSF in vitro; however, this combination did not result in a statistically significant reduction in tumor growth in vivo. These studies demonstrate that a Cu(CQ)2 formulation suitable for intravenous use can be prepared, but this formulation used alone or in combination with DSF was not efficacious. The methods described are suitable for development formulations of other analogues of 8-hydroxyquinoline which could prove to be more potent.

Transcriptomic profiling of purified patient-derived dopamine neurons identifies convergent perturbations and therapeutics for Parkinson's disease

While induced pluripotent stem cell (iPSC) technologies enable the study of inaccessible patient cell types, cellular heterogeneity can confound the comparison of gene expression profiles between iPSC-derived cell lines. Here, we purified iPSC-derived human dopaminergic neurons (DaNs) using the intracellular marker, tyrosine hydroxylase. Once purified, the transcriptomic profiles of iPSC-derived DaNs appear remarkably similar to profiles obtained from mature post-mortem DaNs. Comparison of the profiles of purified iPSC-derived DaNs derived from Parkinson's disease (PD) patients carrying LRRK2 G2019S variants to controls identified significant functional convergence amongst differentially-expressed (DE) genes. The PD LRRK2-G2019S associated profile was positively matched with expression changes induced by the Parkinsonian neurotoxin rotenone and opposed by those induced by clioquinol, a compound with demonstrated therapeutic efficacy in multiple PD models. No functional convergence amongst DE genes was observed following a similar comparison using non-purified iPSC-derived DaN-containing populations, with cellular heterogeneity appearing a greater confound than genotypic background.

Zinc chelation reduces hippocampal neurogenesis after pilocarpine-induced seizure

Several studies have shown that epileptic seizures increase hippocampal neurogenesis in the adult. However, the mechanism underlying increased neurogenesis after seizures remains largely unknown. Neurogenesis occurs in the subgranular zone (SGZ) of the hippocampus in the adult brain, although an understanding of why it actively occurs in this region has remained elusive. A high level of vesicular zinc is localized in the presynaptic terminals of the SGZ. Previously, we demonstrated that a possible correlation may exist between synaptic zinc localization and high rates of neurogenesis in this area after hypoglycemia. Using a lithium-pilocarpine model, we tested our hypothesis that zinc plays a key role in modulating hippocampal neurogenesis after seizure. Then, we injected the zinc chelator, clioquinol (CQ, 30 mg/kg), into the intraperitoneal space to reduce brain zinc availability. Neuronal death was detected with Fluoro Jade-B and NeuN staining to determine whether CQ has neuroprotective effects after seizure. The total number of degenerating and live neurons was similar in vehicle and in CQ treated rats at 1 week after seizure. Neurogenesis was evaluated using BrdU, Ki67 and doublecortin (DCX) immunostaining 1 week after seizure. The number of BrdU, Ki67 and DCX positive cell was increased after seizure. However, the number of BrdU, Ki67 and DCX positive cells was significantly decreased by CQ treatment. Intracellular zinc chelator, N,N,N0,N-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), also reduced seizure-induced neurogenesis in the hippocampus. The present study shows that zinc chelation does not prevent neurodegeneration but does reduce seizure-induced progenitor cell proliferation and neurogenesis. Therefore, this study suggests that zinc has an essential role for modulating hippocampal neurogenesis after seizure.

Mesoporous silica nanoparticle-based H2O2 responsive controlled-release system used for Alzheimer's disease treatment

Metal ions play important roles in amyloid aggregation and neurotoxicity. Metal-ion chelation therapy has been used in clinical trials for Alzheimer's disease (AD) treatment. However, clinical trial studies have shown that long-term use of metal chelator can cause adverse side effect, subacute myelo-optic neuropathy. Nanoparticle engineering processes have become promising approaches for efficiently drugs delivery. A series of modified mesoporous silica nanoparticles (MSNs) using redox, pH, competitive binding, light, and enzyme as actuators have been demonstrated. Recently, significant advances in sensing oxidative stress have been made by taking advantage of specific chemistry between cellular oxidants such as H(2) O(2) . Here we report a biocompatible delivery platform by using H(2) O(2) responsive controlled-release system to realize target delivery of AD therapeutic metal chelator. The advantage of this novel strategy is that metal chelator can only be released by the increased levels of H(2) O(2) , thus, it would not interfere with the healthy metal homeostasis and can overcome strong side effect of metal chelator after long-term use. By taking advantage of the good biocompatibility, cellular uptake properties, and efficient intracellular release of metal chelators, the delivery system is promising for future in vivo controlled-release biomedical applications.

Characterization of clioquinol and analogues as novel inhibitors of methionine aminopeptidases from Mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis claims about five thousand lives daily world-wide, while one-third of the world is infected with dormant tuberculosis. The increased emergence of multi- and extensively drug-resistant strains of M. tuberculosis (Mtb) has heightened the need for novel antimycobacterial agents. Here, we report the discovery of 7-bromo-5-chloroquinolin-8-ol (CLBQ14)-a congener of clioquinol (CQ) as a potent and selective inhibitor of two methionine aminopeptidases (MetAP) from M. tuberculosis: MtMetAP1a and MtMetAP1c. MetAP is a metalloprotease that removes the N-terminal methionine during protein synthesis. N-terminal methionine excision (NME) is a universally conserved process required for the post-translational modification of a significant part of the proteome. The essential role of MetAP in microbes makes it a promising target for the development of new therapeutics. Using a target-based approach in a high-throughput screen, we identified CLBQ14 as a novel MtMetAP inhibitor with higher specificity for both MtMetAP1s relative to their human counterparts. We also found that CLBQ14 is potent against replicating and aged non-growing Mtb at low micro molar concentrations. Furthermore, we observed that the antimycobacterial activity of this pharmacophore correlates well with in vitro enzymatic inhibitory activity. Together, these results revealed a new mode of action of clioquinol and its congeners and validated the therapeutic potential of this pharmacophore for TB chemotherapy.

Pharmacokinetics and distribution of clioquinol in golden hamsters

Clioquinol (5-chloro-7-iodo-8-quinolinol) is a zinc and copper chelator that can dissolve amyloid deposits and may be beneficial in Alzheimer's disease. Prion diseases are also degenerative CNS disorders characterised by amyloid deposits. The pharmacokinetics and tissue distribution of drugs active against prions may clarify their targets of action. We describe the pharmacokinetics of clioquinol in hamster plasma, spleen and brain after single and repeated oral or intraperitoneal administration (50 mg kg(-1)), as well as after administration with the diet. A single intraperitoneal administration led to peak plasma clioquinol concentrations after 15 min (Tmax), followed by a decay with an apparent half-life of 2.20 +/- 1.1 h. After oral administration, Tmax was reached after 30 min and was followed by a similar process of decay; the AUC(0-last) was 16% that recorded after intraperitoneal administration. The Cmax and AUC values in spleen after a single administration were about 65% (i.p.) and 25% (p.o.) those observed in blood; those in liver were 35% (p.o.) those observed in blood and those in brain were 20% (i.p.) and 10% (p.o.) those observed in plasma. After repeated oral doses, the plasma, brain and spleen concentrations were similar to those observed at the same times after a single dose. One hour after intraperitoneal dosing, clioquinol was also found in the ventricular CSF. Clioquinol was also given with the diet; its morning and afternoon concentrations were similar, and matched those after oral administration. No toxicity was found after chronic administration. Our results indicate that clioquinol, after oral administration with the diet, reaches concentrations in brain and peripheral tissues (particularly spleen) that can be considered effective in preventing prion accumulation, but are at least ten times lower than those likely to cause toxicity.

Oral administration of metal chelator ameliorates motor dysfunction after a small hemorrhage near the internal capsule in rat

Cerebral hemorrhage leads to local production of free iron, radicals, cytokines, etc. To investigate whether a decrease of iron-mediated radical production influences functional recovery after intracerebral hemorrhage (ICH), a modified ICH rat model with a small hemorrhage near the internal capsule (IC) accompanied with relatively severe motor dysfunction was first developed. Then clioquinol (CQ), an iron chelator that reduces hydroxyl radical production, was orally administrated. Injection of different doses of Type IV collagenase (1.4 mul 1-200 U/ml) into the left striatum near the IC in Wistar rats showed that injection of 7.5 U/ml collagenase resulted in a small hemorrhoidal lesion near the IC with relatively severe motor dysfunction (IC model). Retrograde labeling of neurons in the sensory-motor cortex and axons in the corticospinal tract using Fluoro-gold (FG) injection into the spinal cord (C3-C4) showed that few labeled neurons in the sensory-motor cortex were detected in the IC model, FG-labeled axons disappeared, and FG-including ED-1-positive cells appeared within 24 hr in the IC. Assessments of behavior and histologic analysis after oral administration of CQ in the IC model indicated that oral administration of CQ prevented a decrease of FG-labeled neurons, and resulted in better motor-function recovery. CQ inhibited hydrogen peroxide-induced cell toxicity in oligodendrocytes in vitro, but not in neurons. Our data suggests that CQ ameliorated motor dysfunction after a small hemorrhage near the IC by a mechanism that is related to reduction of chain-reactive hydroxyl radical production in oligodendrocytes.

Pharmacological strategies for the prevention of Alzheimer's disease

This review examines key pharmacological strategies that have been clinically studied for the primary or secondary prevention of Alzheimer's disease. Much information (neuropsychological, genetic and imaging) is already available to characterise an individual's risk for developing Alzheimer's disease. However, regulatory pathways for obtaining a prevention indication are less well charted, and such trials tend to involve 3- to 7-year studies of 1000 - 5000 individuals, depending on baseline status. Treatments developed for prevention will also need to have superior safety. For these reasons, > 100 proprietary pharmacological products are currently being developed for an Alzheimer's disease treatment, but only a few are being studied for prevention. Randomised trial data are available for antihypertensive agents (calcium channel blockers, angiotensin-converting enzyme inhibitors), pravastatin, simvastatin, conjugated oestrogen, raloxifene, rofecoxib, CX516 (AMPA agonist) and cholinesterase inhibitors regarding efficacy for Alzheimer's disease prevention. At least four large prevention trials of conjugated oestrogen, selenium and vitamin E, Ginkgo biloba and statins are currently underway. Strategies using other agents have not yet been evaluated in Alzheimer's disease prevention clinical trials. These include anti-amyloid antibodies, active immunisation, selective secretase inhibitors and modulators, microtubule stabilisers (e.g., paclitaxel), R-flurbiprofen, xaliproden, ONO-2506, FK962 (somatostatin releaser), SGS 742 (GABA(B) antagonist), TCH 346 (apoptosis inhibitor), Alzhemedtrade mark, phophodiesterase inhibitors, rosiglitazone, leuprolide, interferons, metal-protein attenuating compounds (e.g., PBT2), CX717, rasagaline, huperzine A, antioxidants and memantine. Studies combining lifestyle modification and drug therapy have not been conducted. Full validation of surrogate markers for disease progression (such as amyloid imaging) should further facilitate drug development. Reducing the complexity of prevention trials and gaining regulatory consensus of design is a high priority for the field.

Determination of 5-chloro-7-iodo-8-quinolinol (clioquinol) in plasma and tissues of hamsters by high-performance liquid chromatography and electrochemical detection

This paper describes a method of determining clioquinol levels in hamster plasma and tissue by means of HPLC and electrochemical detection. Clioquinol was separated on a Nucleosil C18 300 mm x 3.9 mm i.d. 7 microm column at 1 ml/min using a phosphate/citrate buffer 0.1M (400 ml) with 600 ml of a methanol:acetonitrile (1:1, v/v) mobile phase. The retention times of clioquinol and the IS were, respectively, 11.6 and 8.1 min; the quantitation limit (CV>8%) was 5 ng/ml in plasma and 10 ng/ml in tissues. The intra- and inter-assay accuracies of the method were more than 95%, with coefficients of variation between 3.0 and 7.7%, and plasma and tissue recovery rates of 72-77%. There was a linear response to clioquinol 5-2000 ng/ml in plasma, and 10-1000 ng/g in tissues. The method is highly sensitive and selective, makes it possible to study the pharmacokinetics of plasma clioquinol after oral administration and the distribution of clioquinol in tissues, and could be used to monitor plasma clioquinol levels in humans.

Otic drops used to clear a blocked grommet: an in vitro prospective randomized controlled study with blinded assessment

Clinicians often prescribe otic drops anecdotally to try and clear grommets blocked with blood. We carried out an in vitro double-blind randomized controlled study comparing the efficacy of sodium bicarbonate, Locorten Vioform and olive oil drops in clearing Shah grommets placed in 'artificial ears' and blocked with blood in a standardized fashion. There were 33 grommets in each group, and drops were inserted three times a day for 7 days. Olive oil drops cleared 17 of 33 (51.51%), Locorten Vioform cleared one of 33 (3%) and sodium bicarbonate cleared zero of 33 (0%) blocked grommets. Statistical comparison between pairs indicates that olive oil was significantly better than both Locorten Vioform (P < 0.001) and sodium bicarbonate drops (P < 0.001) at clearing grommets blocked with blood.

Comparative frequency of patch test reactions to topical antibiotics

BACKGROUND

Neomycin, clioquinol and fusidic acid are all topical antibiotics widely used in dermatological practice in the U.K., either as a single agent or in combination with topical corticosteroids. However, an adverse effect of topical antibiotics is contact sensitization.

OBJECTIVES

To examine the frequency of positive patch test reactions to fusidic acid, clioquinol and neomycin.

METHODS

To compare the frequency of allergic patch test reactions over 1 year, we patch tested all patients attending the St John's Institute of Dermatology contact dermatitis clinic for one calendar year with fusidic acid, neomycin and clioquinol.

RESULTS

We patch tested 1119 patients. Positive patch test reactions to neomycin were noted in 40 patients (3.6%), compared with eight patients (0.7%) to clioquinol and three patients (0.3%) to fusidic acid. The frequency of medicament allergy to neomycin was thus five times more common than to clioquinol and ten times more common than to fusidic acid. Although fusidic acid is not part of our extended standard series, it is in our medicaments series. Therefore, in the second part of our study, we reviewed all cases of positive patch test reactions to fusidic acid over the last 20 years. We found that the frequency of hypersensitivity has decreased since the early 1980s despite increasing usage; the current average frequency being 1.62 patch-tested patients per year (1.45%) of those patch tested to the medicaments series). The most common diagnosis in such patients was stasis dermatitis (54.2%).

CONCLUSIONS

The frequency of fusidic acid allergy in an eczema population is low and is comparable with published data from over 10 years ago.

Treatment of Alzheimer's disease with clioquinol

As heavy metal ions may be implicated in the formation of senile plaques in Alzheimer-afflicted brains, treatment with clioquinol was tested in 20 patients with Alzheimer's disease. Clioquinol is a chelator that crosses the blood-brain barrier and has greater affinity for zinc and copper ions than for calcium and magnesium ions. Treatment was given for 21 days at doses of 20 mg/day to 10 patients and 80 mg/day to another 10 patients. The study was blind to the dosages but included no controls. Cerebrospinal fluid (CSF) investigations revealed a significant increase at day 7 and a decrease at day 21 in Tau protein and growth-associated protein (GAP43). These proteins are increased in Alzheimer's disease and considered as rather stable markers. The initial increase may indicate a temporary cytotoxicity to the brain and/or an increased release into the CSF from stores in the tissue, possibly from senile plaques where the proteins are accumulated. The levels of CSF-Tau protein correlated positively and significantly with the serum levels of copper and also with the serum copper/zinc ratio. Clinical ratings showed slight improvement after 3 weeks treatment with clioquinol in this open study.

[Perianal streptococcal dermatitis]

Two boys aged 6 and 9 years presented with persistent sharply circumscribed perianal erythema. One boy had no other skin findings; the other had additional lesions on the genitalia and extremities. The diagnosis of perianal streptococcal dermatitis was made after streptococci were cultured from skin swabs. This primarily childhood disease should be distinguished from candidiasis and perianal atopic dermatitis. As in our cases, topical therapy is usually ineffective and oral penicillin remains the treatment of choice.

Patient compliance with short-term topical aural antibiotic therapy

Little is known about patient compliance with topical aural antibiotic regimens. The compliance of 50 patients with unilateral otitis externa attending an otolaryngology clinic was studied by comparing the weight of dispensed topical ear preparations before and after completion of a 7-day-course of treatment. A standard was obtained from controlled administration of the preparation under laboratory conditions and the performance of different delivery systems evaluated. Thirty-seven patients re-attended for review with their medication. A total of 34 of 50 patients entering the study (70%) satisfied conventional criteria for compliance. However, over-use of preparations was common and stricter criteria are proposed and applied. Compliance was significantly increased when someone other than the patient administered the preparation.

The same chemicals induce different neurotoxicity when administered in high doses for short term or low doses for long term to rats and dogs

Dose- and term-dependent differences in the location and nature of brain lesions induced in rats and dogs by 2,5-hexanedione (2,5-HD), misonidazole, clioquinol, and acrylamide are reported. Subchronic neuropathies ("distal axonopathy") were induced by low-dose administration of these neurotoxicants and at high doses, lesions caused by acute or subacute neurotoxicity were found in the central nervous system (CNS). In rats, 2,5-HD induced extracellular edema, nerve cell degeneration, and axonal degeneration in the cerebellar and vestibular nuclei. Similar lesions were observed in misonidazole-treated dogs and clioquinol induced nerve cell degeneration in the hippocampus and malacia in the piriform lobes of these animals. In rats, acrylamide induced degeneration of Purkinje cells. Although the mechanism(s) underlying the differential neurotoxicity of high and low doses of these neurotoxicants remains unclear, we suggest certain biochemical mechanisms, cytotoxic edema and excitotoxicity, as factors in the production of such lesions after high-dose treatment.

Combination dermatological products: a comparison of betamethasone dipropionate/clotrimazole/gentamicin sulphate and flumethasone pivalate/clioquinol creams

The combination creams, betamethasone dipropionate/clotrimazole/gentamicin sulphate and flumethasone pivalate/clioquinol, were compared in patients with corticosteroid responsive dermatoses and/or cutaneous fungal and/or bacterial infections. Medication was applied to affected areas twice daily for 28 days. Of 67 patients enrolled, 31 treated with betamethasone/clotrimazole/gentamicin and 33 given flumethasone pivalate/clioquinol were evaluated for efficacy and safety each week during therapy and once 14 days post-therapy. Disease signs and symptoms were less severe in the group given betamethasone/clotrimazole/gentamicin than in the comparative group at days 7 (P = 0.04), 21 (P = 0.02), 28 (P = 0.09), and 42 (P = 0.09) and at patients' last valid visit (P = 0.06). By the last valid visit, signs/symptoms had improved by 82% for patients treated with betamethasone/clotrimazole/gentamicin versus 68% for those treated with flumethasone pivalate/clioquinol. Patients given betamethasone/clotrimazole/gentamicin had statistically significantly better therapeutic responses than those given flumethasone pivalate/clioquinol at day 7 and, by the last valid visit, 19/31 (61%) patients given betamethasone/clotrimazole/gentamicin compared to 15/33 (45%) given flumethasone pivalate/clioquinol had a complete cure or an excellent therapeutic response. Median time of onset of relief of erythema and pruritus was approximately 2 days, regardless of treatment. No adverse reactions were reported.

Effects of metal-containing drugs taken simultaneously with clioquinol upon clinical features of SMON

In order to explore the effects of metals upon the subsequent onset of several clinical events in SMON, a retrospective cohort study was attempted. Study subjects were 216 "exposed" patients and 149 "unexposed" patients. "Exposure" was defined as the simultaneous ingestion of metal-containing drugs with clioquinol before the onset of neurological disorders. These two cohorts were identified from 531 patients among 832 patients, collected by the nationwide survey in 1975 and 1976. Effects provoked by ingestion of five metals (alminum, calcium, magnesium, copper and bismuth) were evaluated by relative risks with and without adjustment of the total amount of clioquinol ingested. Adjusted relative risks were estimated by maximum likelihood method. Significance of relative risk was determined by its 95% confidence interval. Following major findings emerged from the present analysis. (1) Simultaneous ingestion of Al-, Ca-, Mg-, Cu- or Bi-containing drugs with clioquinol significantly reduced the risk of developing motor disturbances. (2) Risk of developing visual disturbances were favorably modified by Al-containing drugs. (3) Clinical severity was significantly reduced by ingestion of Al-, Ca-, Mg- or Bi-containing drugs. (4) About 2-fold increase in risk of unfavorable clinical course was demonstrated by Al-containing drugs. (5) Onset of both green-fur on the tongue and relapse appeared unrelated to the metal-containing drugs ingested. (6) Combined ingestion of two kinds of metal-containing drugs with clioquinol appeared to yield more favorable effects than single ingestion of metal-containing drugs. (7) Al- or Bi-containing drugs demonstrated the strongest association with clinical features of SMON, followed by the drugs containing Mg or Ca. Cu-containing drugs had little association.

Metabolism of 14C-iodochlorhydroxyquin in the dog and the rat

The disposition and metabolism of iodochlorhydroxyquin (clioquinol), an amebicidal drug with neurotoxic properties, were studied in dogs and rats with 14C-labelled drug. Pharmacokinetic studies in the dog demonstrated that the compound was well absorbed; the bioavailability was 36% of the dose of 1 mg/kg. The serum half-life was 1.3-1.8 h. In both the dog and the rat, biliary excretion was a major route of elimination. The dog excreted 27% of an intravenously administered dose (1 mg/kg) in the bile within 2 h; the rat excreted 39% of the dose (5 mg/kg i.v.) in less than 3 h. Elimination via the renal route was also substantial in both species. Urinary and biliary metabolites were separated by TLC (thin layer chromatography) and identified as sulfate and glucuronide conjugates in both species. No evidence for any other metabolites was found. A significant difference was observed between the dog and the rat in the extent of conjugation; the percentage radioactivity in the urine accounted for by the unchanged compound was six to twenty times greater for the dog than for the rat. The species differences in the disposition and metabolism of the compound might explain its greater toxicity in the dog than in the rat.

Percutaneous absorption of iodochlorhydroxyquin in humans

Iodochlorhydroxyquin (I) is used in the treatment of diaper rash and other skin disorders, and is presumed to undergo little or no percutaneous absorption. The absorption of (I) from a 3% cream was studied in 5 normal male subjects after a single application of the cream for 12 h. Plasma levels of the drug were followed for 24 h after initial application while urinary excretion was measured for 54 h. (I) was extracted from plasma and urine and assayed by high-performance liquid chromatography. The drug in the range of 0.37-0.56 micrograms/ml was detected in plasma 2 h after application and persisted throughout the treatment period. The mean excretion rate after 12 h of application was 58.4 micrograms/h and the excretion rate was 8.8 micrograms/h at 42 h posttreatment. The elimination rate constant was calculated to be 0.15 h-1. Approximately 40% of the drug was absorbed over the 12-h application period. From the above results it is apparent that significant percutaneous absorption of (I) occurs.

Appearance of intoxication in rats by intraperitoneal administration of clioquinol

The investigation was undertaken to study the neurological symptoms in rats caused by maintaining high plasma concentration of about 30 nmol/ml or more, of clioquinol. Clioquinol suspension which was prepared using polysorbate 80 was administered intraperitoneally to rats and plasma and tissue concentrations were determined. On administration of clioquinol of 100 and 200 mg/kg, the mean plasma concentrations of clioquinol reached maximum values of 30 and 58 nmol/ml, respectively, after 0.5-1 h and thereafter decreased rapidly. With 400 mg/kg, however, plasma concentration reached maximum value of about 75 nmol/ml and fell slowly. By single and repeated administration of the suspension, clioquinol was distributed in the liver and kidney at a high concentration, and also in the nervous system. In experiments on appearance of neurotoxicity in rats by repeated administration of the suspension, all of 10 rats administered intraperitoneally with 100 mg/kg/d did not develop any neurological symptoms for about 30 d. On the other hand, one of 10 and 7 of 13 rats administered with 200 and 400 mg/kg/d, respectively, developed ataxia in the hind legs or all legs on the 3rd to the 12th day after starting administration. Pathologically, a slight change of the peripheral nerve, central chromatolysis of the anterior horn neuron and severe neuronal degeneration of the Ammon's horn were observed in the rats with ataxia.

Travellers' diarrhoea: prevention by chemoprophylaxis

The chemoprophylaxis of travellers' diarrhoea by iodochlorhydroxyquinoline combinations, neomycin and phthalsulphathiazole, furazolidone, bismuth salicylates and streptotriad is reviewed. Streptotriad is regarded as a highly effective prophylactic against travellers' diarrhoea. Some elementary food hygiene precautions are detailed.

Comparative merits of two topical corticosteroid antimicrobial drugs

The anti-inflammatory and antimicrobial activities of two topical creams, one containing halcinonide, neomycin and nystatin (HNN), and the other betamethasone valerate, gentamicin, iodochlorhydroxyquin and tolnaftate (BGI), were compared in a randomized, parallel study of 154 patients (eighty-seven secondarily infected eczematous dermatoses; sixty-seven cutaneous candidiasis). Repeated clinical assessments showed that the two creams produced equivalent therapeutic responses both in patients with infected eczematous lesions and candidiasis. HNN and BGI creams eradicated the bacterial pathogens isolated prior to treatment in 80% and 76%, respectively, of the patients with eczematous dermatoses. The organism most frequently isolated in these patients was S. aureus. Local irritation prompting discontinuance of therapy occurred in just one patient receiving HNN, and two patients receiving BGI.

Neurotoxicity of halogenated hydroxyquinolines: clinical analysis of cases reported outside Japan

An analysis is presented of 220 cases of possible neurotoxic reactions to halogenated hydroxyquinolines reported from outside Japan. In 80 cases insufficient information was available for adequate comment and in 29 a relationship to the administration of clioquinol could be excluded. Of the remainder, a relationship to clioquinol was considered probable in 42 and possible in 69 cases. In six of the probable cases the neurological disturbance consisted of an acute reversible encephalopathy usually related to the ingestion of a high dose of clioquinol over a short period. The most common manifestation, observed in 15 further cases, was isolated optic atrophy. This was most frequently found in children, many of whom had received clioquinol as treatment for acrodermatitis enteropathica. In the remaining cases, a combination of myelopathy, visual disturbance, and peripheral neuropathy was the most common manifestation. Isolated myelopathy or peripheral neuropathy, or these manifestations occurring together, were infrequent. The onset of all manifestations (except toxic encephalopathy) was usually subacute, with subsequent partial recovery. Older subjects tended to display more side effects. The full syndrome of subacute myelo-optic neuropathy was more frequent in women, but they tended to have taken greater quantities of the drug.

Primary irritant dermatitis from topical clioquinol

During the 2-year period 1976--1977, seven patients were studied with primary irritant dermatitis from topical preparations containing clioquinol. During the same period contact hypersensitivity to the compound was recorded in 35 eczema patients. Six of the seven patients with clioquinol irritancy had used creams containing 3% large crystal clioquinol and fluorinated steroids. One patient had used 6% small crystal clioquinol cream. Challenge tests with 3% small crystal and large crystal clioquinol creams showed that crystal size did not affect the appearance of irritant dermatitis.

Percutaneous absorption of clioquinol (Vioform)

The percutaneous absorption of clioquinol from three different preparations for skin treatment (Vioform cream, Locacorten-Vioform cream and Vioform-Hydrocortisone cream) was evaluated. After topical dosages corresponding to 30 mg clioquinol, concentrations in the blood were below the detection limit of the analytical procedure, i.e., smaller than 0.02 micrograms/ml; therefore the percutaneous absorption was evaluated by measuring cumulative urinary excretion of clioquinol and was compared to that found after an equivalent oral dose. The study was carried out in 4 healthy volunteers. The topical preparations were applied under occlusive dressings. Following epicutaneous application of the three topicals in quantities containing 30 mg clioquinol each, the urinary excretion of the drug was between 1.2 and 3.6% of the applied dose. When the same dose of clioquinol was administered orally to two volunteers, 52.4 and 92.9% of the dose was excreted in the urine. Taking the urinary elimination as the minimal amount of drug absorbed, the extent of percutaneous absorption from the three dermatological preparations amounted to 1.2-3.6% of the applied dose. There was no difference in the pattern of urinary excretion products among the three topicals and the oral formulation. The bulk of clioquinol was excreted as glucuronide (mean: 96 +/- 3%) and only a small fraction was excreted as sulfate (mean: 3.8 +/- 3%). A small amount of free clioquinol (1.1%) was measured in 1 subject only after the oral dose.

Iodochlorhydroxyquin-hydrocortisone treatment of fungal infections. Double-blind trial

A double-blind multicenter study compared the antifungal effectiveness of an iodochlorhydroxyquin-hydrocoritsone cream with that of its individual components in 354 patients with cutaneous fungal infections. After seven days of treatment, the combination was considerably better than hydrocortisone or the cream vehicle with respect to erythema, scaling, itching, and patients' and physicians' evaluations. The proportion of patients in the iodochlorhydroxyquin-hydrocortisone and iodochlorhydroxyquin groups who changed from positive results on potassium hydroxide examination at baseline to negative results on potassium hydroxide examination after treatment was significantly greater than that in the hydrocortisone and placebo groups. The conversion rate associated with the iodochlorhydroxyquin-hydrocortisone and the iodochlorhydroxyquin treatments was significantly different from that associated with hydrocortisone alone or placebo treatment.