Proteomic characterisation of perhexiline treatment on THP-1 M1 macrophage differentiation

Background

Dysregulated inflammation is important in the pathogenesis of many diseases including cancer, allergy, and autoimmunity. Macrophage activation and polarisation are commonly involved in the initiation, maintenance and resolution of inflammation. Perhexiline (PHX), an antianginal drug, has been suggested to modulate macrophage function, but the molecular effects of PHX on macrophages are unknown. In this study we investigated the effect of PHX treatment on macrophage activation and polarization and reveal the underlying proteomic changes induced.

Methods

We used an established protocol to differentiate human THP-1 monocytes into M1 or M2 macrophages involving three distinct, sequential stages (priming, rest, and differentiation). We examined the effect of PHX treatment at each stage on the polarization into either M1 or M2 macrophages using flow cytometry, quantitative polymerase chain reaction (qPCR) and enzyme linked immunosorbent assay (ELISA). Quantitative changes in the proteome were investigated using data independent acquisition mass spectrometry (DIA MS).

Results

PHX treatment promoted M1 macrophage polarization, including increased STAT1 and CCL2 expression and IL-1β secretion. This effect occurred when PHX was added at the differentiation stage of the M1 cultures. Proteomic profiling of PHX treated M1 cultures identified changes in metabolic (fatty acid metabolism, cholesterol homeostasis and oxidative phosphorylation) and immune signalling (Receptor Tyrosine Kinase, Rho GTPase and interferon) pathways.

Conclusion

This is the first study to report on the action of PHX on THP-1 macrophage polarization and the associated changes in the proteome of these cells.

Determination of the 4-monohydroxy metabolites of perhexiline in human plasma, urine and liver microsomes by liquid chromatography

The use of perhexiline (PHX) is limited by hepatic and neurological toxicity associated with elevated concentrations in plasma that are the result of polymorphism of the cytochrome P450 2D6 isoform (CYP2D6). PHX is cleared by hepatic oxidation that produces three 4-monohydroxy metabolites: cis-OH-PHX, trans1-OH-PHX and trans2-OH-PHX. The current study describes an HPLC-fluorescent method utilising pre-column derivatization with dansyl chloride. Following derivatization, the metabolites were resolved on a C18 column with a gradient elution using a mobile phase composed of methanol and water. The method described is suitable for the quantification of the metabolites in human plasma and urine following clinical doses and for kinetic studies using human liver microsomes. The method demonstrates sufficient sensitivity, accuracy and precision between 5.0 and 0.01, 50.0 and 0.2 and 1.0 and 0.005 mg/l in human plasma, urine and liver microsomes, respectively, with intra-assay coefficients of variation and bias <15%, except at the lowest limit of quantification (<20%). The inter-assay coefficients of variation and bias were <15%. The application of this method to plasma and urine samples of five CYP2D6 extensive metaboliser (EM) patients at steady state with respect to PHX dosing determined that the mean (+/-S.D.) renal clearances of trans1-OH-PHX and cis-OH-PHX were 1.58+/-0.35 and 0.16+/-0.06l/h, respectively. The mean (+/-S.D.) dose recovered in urine as free and glucuronidated 4-monohydroxy PHX metabolites was 20.6+/-11.6%.

CYP2B6, CYP2D6, and CYP3A4 Catalyze the Primary Oxidative Metabolism of Perhexiline Enantiomers by Human Liver Microsomes

The cytochrome P450 (P450)-mediated 4-monohydroxylations of the individual enantiomers of the racemic antianginal agent perhexiline (PHX) were investigated in human liver microsomes (HLMs) to identify stereoselective differences in metabolism and to determine the contribution of the polymorphic enzyme CYP2D6 and other P450s to the intrinsic clearance of each enantiomer. The cis-, trans1-, and trans2-4-monohydroxylation rates of (+)- and (-)-PHX by human liver microsomes from three extensive metabolizers (EMs), two intermediate metabolizers (IMs), and two poor metabolizers (PMs) of CYP2D6 were measured with a high-performance liquid chromatography assay. P450 isoform-specific inhibitors, monoclonal antibodies directed against P450 isoforms, and recombinantly expressed human P450 enzymes were used to define the P450 isoform profile of PHX 4-monohydroxylations. The total in vitro intrinsic clearance values (mean +/- S.D.) of (+)- and (-)-PHX were 1376 +/- 330 and 2475 +/- 321, 230 +/- 225 and 482 +/- 437, and 63.4 +/- 1.6 and 54.6 +/- 1.2 microl/min/mg for the EM, IM, and PM HLMs, respectively. CYP2D6 catalyzes the formation of cis-OH-(+)-PHX and trans1-OH-(+)-PHX from (+)-PHX and cis-OH-(-)-PHX from (-)-PHX with high affinity. CYP2B6 and CYP3A4 each catalyze the trans1- and trans2-4-monohydroxylation of both (+)- and (-)-PHX with low affinity. Both enantiomers of PHX are subject to significant polymorphic metabolism by CYP2D6, although this enzyme exhibits distinct stereoselectivity with respect to the conformation of metabolites and the rate at which they are formed. CYP2B6 and CYP3A4 are minor contributors to the intrinsic P450-mediated hepatic clearance of both enantiomers of PHX, except in CYP2D6 PMs.

Metabolic therapeutics in angina pectoris: history revisited with perhexiline

The ever-increasing burden of ischaemic heart disease and its common manifestation chronic angina pectoris calls for the exploration of other treatment options for those patients who despite the maximum conventional pharmacological and surgical interventions continue to suffer. Such exploration has led to the increasing use of new metabolically acting antianginal agents and the re-emergence of an old and somewhat forgotten pharmacological agent, perhexiline maleate. This review aims to update the cardiac nurse with knowledge to manage the care a patient receiving perhexiline maleate treatment and provide a brief review of three new metabolic agents: trimetazidine, ranolazine and etomoxir.

Correlation of CYP2D6 genotype with perhexiline phenotypic metabolizer status

Perhexiline is metabolized by CYP2D6 and has concentration-related hepatoxicity and peripheral neuropathy. The risk of toxicity is reduced using therapeutic drug monitoring. CYP2D6 genotyping before therapy may allow earlier appropriate dosing. This study aimed to determine whether assessment of CYP2D6 genotype in patients on perhexiline could predict accurately metabolizer status as determined by the perhexiline metabolic ratio (MR). Blood samples from patients stabilized on perhexiline were analysed for CYP2D6 genotype and for concentrations of perhexiline and its hydroxy metabolite. The MR was determined. Of 74 patients, five were poor metabolizers (PM) defined by a MR<0.4, and the remainder were extensive metabolizers (EM). The genotypes were: *1/*1 (n=21), *1/*4 (n=18), *1/*2 (n=12), *1/*3 (n=2), *1/*5 (n=1), *1/*9 (n=2), *1/*10 (n=2), *2/*4 (n=4), *2/*2 (n=3), *4/*41 (n=3), *2/*41 (n=1), *41/*41 (n=1), *4/*9 (n=1), *4/*5 (n=1), *5/*6 (n=1) and *4/*6 (n=1). Allele frequencies were consistent with those reported in population studies. The 3 PMs with the lowest MR were predicted by genotype (*4/*5, *5/*6, *4/*6). The other 2 PMs had intermediate metabolizer genotypes and were on CYP2D6 inhibiting drugs. Amongst the EMs, the highest MR was associated with *1 and *2 allele combinations and the MR was progressively lower with the presence of alleles with intermediate function (*9, *10, *41) followed by alleles with no functional product (*3, *4, *5, *6). Thus, a gene-dose effect was observed. Genotype predicted PM phenotype and also intermediate metabolizers. Determination of CYP2D6 genotype before therapy with perhexiline may help predict perhexiline dose requirements and reduce the risk of perhexiline concentration-related toxicity.

Polymorphic hydroxylation of perhexiline in vitro

AIMS

The aims of this study were to examine the in vitro enzyme kinetics and CYP isoform selectivity of perhexiline monohydroxylation using human liver microsomes.

METHODS

Conversion of rac-perhexiline to monohydroxyperhexiline by human liver microsomes was assessed using a high-performance liquid chromatography assay with precolumn derivatization to measure the formation rate of the product. Isoform selective inhibitors were used to define the CYP isoform profile of perhexiline monohydroxylation.

RESULTS

The rate of perhexiline monohydroxylation with microsomes from 20 livers varied 50-fold. The activity in 18 phenotypic perhexiline extensive metabolizer (PEM) livers varied about five-fold. The apparent Km was 3.3 +/- 1.5 micro m, the Vmax was 9.1 +/- 3.1 pmol min-1 mg-1 microsomal protein and the in vitro intrinsic clearance (Vmax/Km) was 2.9 +/- 0.5 micro l min-1 mg-1 microsomal protein in the extensive metabolizer livers. The corresponding values in the poor metabolizer livers were: apparent Km 124 +/- 141 micro m; Vmax 1.4 +/- 0.6 pmol min-1 mg-1 microsomal protein; and intrinsic clearance 0.026 micro l min-1 mg-1 microsomal protein. Quinidine almost completely inhibited perhexiline monohydroxylation activity, but inhibitors selective for other CYP isoforms had little effect.

CONCLUSIONS

Perhexiline monohydroxylation is almost exclusively catalysed by CYP2D6 with activities being about 100-fold lower in CYP2D6 poor metabolizers than in extensive metabolizers. The in vitro data predict the in vivo saturable metabolism and pharmacogenetics of perhexiline.

Method for the analysis of perhexiline and its hydroxy metabolite in plasma using high-performance liquid chromatography with precolumn derivatization

A high-performance liquid chromatographic method for the analysis of perhexiline and its monohydroxy metabolite in plasma has been developed. After a simple extraction procedure, the analytes are derivatized over a 30-min period with trans-4-nitrocinnamoyl chloride. The derivatized products are monitored at 340 nm following separation on a 5-micron phenyl reversed-phase column under isocratic conditions. The limits of detection for perhexiline and its hydroxy metabolite are 0.03 and 0.02 mg/l, respectively. The between-day and within-day assay coefficients of variation for perhexiline and its hydroxy metabolite at concentrations of 0.2 and 1.0 mg/I were less than 10%. The method has proved robust and suitable for the routine monitoring of perhexiline and hydroxyperhexiline.

[Genetic polymorphism of the metabolism of drugs used in cardiac diseases]

The genetic determinants of the metabolism of certain drugs used in cardiology is one predictable cause of variability in their pharmacokinetics and effects. Genetic polymorphism of the metabolism of drugs is characterised by the existence of several metabolic phenotypes, usually 2, which allow distinction between fast and slow metabolisers. Clinical identification of these phenotypes is relatively simple. The enzymatic deficiency in slow metabolisers concerns a specific metabolic pathway responsible for the biotransformation of the drug but it respects other eventual metabolic pathways. For a given drug and a given metabolic pathway, slow metabolisers are unable to eliminate the parent product by hepatic metabolism. When the drug is given orally, the plasma concentrations of the parent product in slow metabolisers are 5 to 25 times higher than those observed in fast metabolisers. Depending on the given drug, doses usually well tolerated by fast metabolisers may cause excessive effects in slow metabolisers. The pharmacodynamic consequences of genetic polymorphism on the metabolism of drugs depend essentially on the therapeutic index of the drug concerned and on the activity of the metabolites formed by the genetically determined pathway of the parent product. The pharmacokinetic and pharmacodynamic consequences of the two main genetic polymorphisms concerning drugs used in cardiology are discussed: the polymorphism of N acetylation and that of cytochrome P-450 IID6.

Synthesis and pharmacological properties of "soft drug" derivatives related to perhexiline

In the hope of reducing the toxicity of perhexiline, a series of 27 cyclohexylaralkylamines II based on the "soft drug" concept and incorporating an amide function were synthesized. In a preliminary screening, compounds were evaluated for their alpha-adrenolytic activities. Several derivatives, especially N-(cyclohexylphenylmethyl)-2-(cyclohexyl-methylamino)acetamide (3), N-(cyclohexylphenylmethyl)-2-(homoveratrylmethylamino)acetam ide (7), and N-[2-(cyclohexylamino)ethyl]-alpha-cyclohexylbenzeneacetamide (23) had the same activity range as perhexiline in vitro in rat aorta strips. The in vitro metabolism of these three molecules was then investigated and compared to that of perhexiline. The effect upon the alpha-adrenolytic activity of introducing various N-aralkylamine groups on II was examined. Structure/activity relationships are discussed.

The enterohepatic circulation of perhexiline metabolites in the male Wistar rat

1. The biliary excretion of some perhexiline metabolites has been assessed in male Wistar rats with biliary cannulation. 2. After intragastric administration of perhexiline maleate (2 mg/kg body weight) multiple perhexiline metabolites were detected in bile. 3. When aliquots of this metabolite-laden bile were administered intraduoduodenally to further 'recipient' rats with biliary cannulation, similar metabolites were detected in the bile of these rats, but at reduced concentrations equivalent to 30-35% of those present in the bile of 'donor' rats. 4. These findings indicate that in the male Wistar rat, there may be substantial enterohepatic circulation of some perhexiline metabolites.

Studies on the metabolism of perhexiline in man

We have studied the disposition of perhexiline and its two major metabolites, M1 and M3, in healthy volunteers and in patients with biliary T-tube drains after cholecystectomy. In healthy volunteers the genetic control for impaired hepatic oxidation is identical for debrisoquine, sparteine, and perhexiline. Poor metabolizers demonstrate markedly reduced production and excretion of the major metabolite, M1. Their production of M3 is also reduced, but to a lesser degree than for M1, confirming substrate stereoselectivity by hepatic oxidases. Biphasic urinary elimination of M1 and M3 is seen in intact extensive oxidizers, whereas only the first phase is apparent in patients with biliary T-tube drainage. This suggests the possibility of enterohepatic recycling of these compounds, which may account for their prolonged elimination. More than 90% of an ingested dose of perhexiline maleate remains unaccounted for at 24 h after ingestion, even in extensive metabolizers. A careful, radiolabelled tissue-distribution study is warranted to elucidate the complicated metabolic fate of perhexiline.

Perhexiline maleate treatment for severe angina pectoris--correlations with pharmacokinetics

Perhexiline maleate, which causes inhibition of myocardial fatty acid catabolism with a concomitant increase in glucose utilization, is particularly useful in the management of patients with severe angina pectoris. While perhexiline exerts no significant negative inotropic or dromotropic effects, its short- and long-term use has hitherto been restricted because of complex pharmacokinetics and the eventual development, in many patients, of hepatitis and peripheral neuropathy. Correlations between perhexiline dose, plasma drug concentrations, efficacy and development of toxicity were examined prospectively in 3 groups of patients. The first group (n = 29) were patients in whom perhexiline was added to previously prescribed anti-anginal medication for short-term (pre-surgical or post-myocardial infarction) control of angina pectoris. Over a mean treatment period of 18 +/- 2 (SEM) days, 13 patients experienced a marked reduction in frequency and severity of attacks. No adverse effects occurred. A second group of patients (n = 19) were treated chronically with 50-400 mg/day of perhexiline, dosage being adjusted to minimize symptoms. Over a mean treatment period of 8.8 +/- 1.7 months, 5 patients became asymptomatic, while 9 developed evidence of hepatitis or neurotoxicity, with concomitant plasma perhexiline concentrations of 720-2680 ng/ml. Subsequently, a further group of similar patients (n = 22) were treated for 12.4 +/- 2.6 months, perhexiline dosage being adjusted to maintain plasma perhexiline concentrations below 600 ng/ml. Nine patients became asymptomatic, while none developed adverse effects. It is concluded that perhexiline is useful both as a short-term adjunct to anti-anginal therapy and in the long-term management of patients unsuitable for coronary artery bypass grafting. The risk of long-term toxicity can be reduced markedly by maintenance of plasma drug concentrations below 600 ng/ml without significantly compromising anti-anginal efficacy.

Stereoselective pharmacokinetics of perhexiline

Blood plasma and urine excretion pharmacokinetics of the (+) and (-) enantiomers of perhexiline have been determined in oral single-dose studies in eight human volunteers, and compared with the pharmacokinetics of the racemate drug in the same subjects. The (-) enantiomer is more rapidly metabolized and eliminated, and is stereoselectively hydroxylated to the cis-monohydroxy-perhexiline. The peak plasma concn of unchanged perhexiline is greater, while that of the cis-monohydroxy-perhexiline metabolite is lower, after administration of the (+) enantiomer than after the (-) enantiomer or the racemate. Similarly, the AUC values for unchanged perhexiline and for the trans-monohydroxy-perhexiline metabolite are greatest and the AUC value for the cis-monohydroxy-perhexiline metabolite is lowest for the (+) enantiomer. The three stereoisomeric forms of perhexiline all had the same times to peak plasma concn of the unchanged drug or of the cis-metabolite, and all three forms had a similar plasma elimination half-life for unchanged perhexiline. Metabolism of racemic perhexiline to the cis-monohydroxy metabolite is the major mechanism of elimination of the drug in man and has been shown to be polymorphic in human populations. The (-) enantiomer which shows stereoselective metabolism to the cis metabolite might therefore show a greater polymorphic effect. Studies with rat-liver microsomal preparations in vitro showed that, in contrast to the human studies in vivo, hydroxylation of perhexiline yields mostly the trans-monohydroxy metabolite. The DA strain of rats exhibited slower rates of hydroxylation in vitro than Wistar or Lewis strains of rats.

Further studies on the pharmacokinetics of perhexiline maleate in humans

We have performed single-dose pharmacokinetic studies on perhexiline in eight young volunteers, each given 300 mg of Pexid orally, using an h.p.l.c. method for the separation and quantification of the drug and its monohydroxy metabolites in plasma and urine. The plasma concentration of the cis-monohydroxyperhexiline (peak of 473 +/- 43 ng/ml at 7.5 +/- 2.0 h) was always higher than for unchanged perhexiline (peak of 112 +/- 20 ng/ml at 6.5 +/- 2.0 h) whereas the concentration of the transmetabolite was either low or undetectable in plasma. These findings indicate the occurrence of stereospecific pre-systemic metabolism of perhexiline which reduces the bioavailability of the parent drug. The plasma elimination half-life of perhexiline was 12.4 +/- 6.1 h (range 7-23 h) while that for cis-monohydroxyperhexiline was 19.9 +/- 7.7 h (range 10-29 h). Not more than 0.3% of unchanged perhexiline was excreted in the urine over five days in eight subjects. Between 3 and 23% of the orally administered drug was excreted as the cis- or trans-monohydroxy metabolites, the ratio of trans to cis metabolites being 0.52 +/- 0.20.

[Clinical pharmacology of calcium inhibitors]

The pharmacokinetics of the commercially available calcium antagonists, diltiazem (Tildiem), nifedipine (Adalate), perhexiline (Pexid), and verapamil (Isoptine) are well known; the pharmacokinetics of bepridil (Cordium) need further study. The properties of nicarpidine, a molecule currently being tested, will also be described. These products are well absorbed from the gastrointestinal tract but undergo variable degrees of transformation during the first passage through the liver. The bioavailabilities of bepridil, diltiazem and nifedipine are of the order of 40 to 60%; those of verapamil and nicarpidine are lower, 10-20% and 15-30%, respectively. The rates of absorption vary according to the derivatives and galenic preparations; in general, they are rapid; peak plasma concentrations are usually obtained one to four hours after administration. Protein binding is high but does not interfere in the distribution; the volumes of distribution of bepridil, diltiazem and verapamil are large (4-5 l/kg); those of nifedipine and nicardipine are smaller (l l/kg). The halflives of diltiazem, nifedipine, nicardipine and verapamil are short (1 to 5 hours); those of bepridil and perhexiline are longer (2 to 3 days). The main method of elimination is by hepatic transformation with high plasma clearance rates: diltiazem and verapamil have pharmacologically active derivatives whose contributions to the overall activities of the drugs are not fully understood. Physiopathological changes of the pharmacokinetic properties of diltiazem and verapamil (elderly patients, hepatic failure) have been described.

Single-dose pharmacokinetics of perhexiline administered orally to humans

A high-performance liquid chromatographic method for the simultaneous determination of perhexiline and its major metabolites, the cis- and trans-monohydroxyperhexilines M1 and M3, respectively, in human plasma or urine has been developed. Perhexiline and its metabolites are extracted from plasma or urine and derivatized with 1-fluoro-2,4-dinitrobenzene. The extracted dinitrophenyl derivatives of drug and metabolites are separated on a Spherisorb S5 ODS column by gradient elution. The limits of detection for perhexiline and its monohydroxy metabolites were 15 and 3 ng/ml, respectively. The inter-assay coefficients of variation for 100 ng/ml perhexiline, 100 ng/ml M1 and 400 ng/ml M3 were 10.5, 7.6 and 5.6%, respectively (n = 9). The method has been employed in a limited kinetic study with five healthy adult male volunteers who received 150-mg and 300-mg Pexid tablets at an interval of one week. In four subjects perhexiline exhibited marked first pass effects, with plasma M1 levels higher than unchanged perhexiline; in the urine M1 was the predominant metabolite except in one subject who had higher M3 than M1 in the 300-mg Pexid study. The fifth subject exhibited a defective capacity to hydroxylate perhexiline; M1 and M3 were not detectable in plasma, and the urinary excretion of the monohydroxyperhexilines was relatively less, with M3 present in higher amounts than M1.

Polymorphic hydroxylation of perhexiline maleate in man

Long term perhexiline maleate therapy causes peripheral neuropathy and hepatic damage in certain subjects. An association between these adverse reactions and a genetically determined relative inability to hydroxylate debrisoquine has been described. This association could indicate either that the effects of perhexiline impair debrisoquine oxidation thus producing a phenocopy, or that perhexiline is polymorphically hydroxylated and that the polymorphism is controlled by the same alleles as control the debrisoquine polymorphism. To test the second possibility, a study investigating the hydroxylation status of a population of healthy volunteer subjects has been performed using perhexiline maleate. Hydroxylation phenotyping was performed on 50 normal volunteers. A standard oral dose was given and plasma and urinary perhexiline, 4-monohydroxyperhexiline (MI metabolite), and 4'monohydroxyperhexiline (MIII metabolite) was measured. The 24-hour plasma perhexiline concentration, the 24-hour plasma MI metabolite concentration, and 12 to 24-hour urinary MI metabolite excretion were clearly bimodal, suggesting the existence of a polymorphism for perhexiline hydroxylation. Poor metabolisers represent 6% of the population studied. Known poor metabolisers of debrisoquine are also poor metabolisers of perhexiline, while known extensive metabolisers of debrisoquine are also extensive metabolisers of perhexiline, indicating that in white British subjects the hydroxylation polymorphism is under identical genetic control for both compounds. The poor metaboliser sub-group exhibited the highest plasma perhexiline levels. Perhexiline phenotyping separates the poor and extensive metaboliser phenotypes much more clearly than other tests and defines a sub-group at risk from perhexiline toxicity. Pretreatment phenotyping using this test, followed by exclusion of poor metabolisers from perhexiline therapy, should substantially reduce the incidence of major adverse effects.

Pharmacokinetics of perhexiline maleate in anginal patients with and without peripheral neuropathy

Perhexiline maleate (Pexid) which has been in general use in France with good results for the treatment of angina pectoris since 1973, may be associated with severe side effects including peripheral neuropathy. The present study is a comparison of the pharmacokinetics of perhexiline maleate in anginal patients with and without signs of peripheral neuropathy. Compared to the latter, those with neuropathy had higher plasma levels of perhexiline, slower hepatic metabolism and a longer plasma half-life. Thus, peripheral neuropathy associated with perhexiline maleate treatment appears to be a direct toxic effect due to accumulation of the drug. The accumulation might result either from a decreased volume of distribution secondary to a loss of body weight, possibly drug-induced, or to slow hepatic metabolism of perhexiline of genetic origin or due to hepatic disease, possibly drug-induced. The neuropathy is rarely an isolated event, as it is often associated with one or more adverse effects of perhexiline.

[Perhexilline maleate: relationship between side-effects, plasma concentrations and rate of metabolism (author's transl)]

In three individuals (2 male and 1 female) with severe side-effects apparently related to the regular ingestion for a period of at least 5 months of perhexiline maleate, the authors studied the rate of fall in plasma levels of the drug, of its monohydroxylated metabolite, blood transaminase and glucose levels following the interruption of therapy. The relationship between these data would indicate two hypotheses which could be tested during future studies: the manner in which the body metabolises the drug would appear to vary in relation to plasma concentration and/or hepatic involvement.

[Neurological disorders and perhexiline maleate therapy. Clinical study of 10 cases. Neuropathological, pharmacocinetic and biochemical studies (author's transl)]

Ten new cases of perhexiline induced peripheral neuropathies are reported. The authors emphasize the possible association of other neurological disorders: cerebellar symptoms in one case, complex tremor in two other cases, marked decrease of photomotor reflexes in one case and disgeusia in another one. The pharmacocinetic study of 4 cases revealed the presence of a low metabolism of the drug in one of them. Polymorphous inclusions have been seen in Schwann cell and endothelial cell cytoplasm in the three patients with electron microscopic study of the nerves. The pathological study of one case showed the demyelination of spinal cord posterior columns. In another case, who died from hepatic coma, the biochemical study of cerebral lipids revealed the low values of cerebrosides and sulfatides in cerebellum and cerebral white matter.

[Hypoglycemia in 2 patients treated with perhexiline maleate]

Hypoglycaemia occurred in two patients treated with perhexiline maleate. The responsibility of the medication is discussed in each case. Blood insulin levels were increased. Blood perhexiline levels decreased very rapidly in the first patient, though much more slowly in the second.