Concentration-time profile for perhexiline and hydroxyperhexiline in patients at steady state

Randomized controlled trial of perhexiline on regression of left ventricular hypertrophy in patients with symptomatic hypertrophic cardiomyopathy (RESOLVE-HCM trial)

BACKGROUND

The presence and extent of left ventricular hypertrophy (LVH) is a major determinant of symptoms in patients with hypertrophic cardiomyopathy (HCM). There is increasing evidence to suggest that myocardial energetic impairment represents a central mechanism leading to LVH in HCM. There is currently a significant unmet need for disease-modifying therapy that regresses LVH in HCM patients. Perhexiline, a potent carnitine palmitoyl transferase-1 (CPT-1) inhibitor, improves myocardial energetics in HCM, and has the potential to reduce LVH in HCM.

OBJECTIVE

The primary objective is to evaluate the effects of perhexiline treatment on the extent of LVH, in symptomatic HCM patients with at least moderate LVH.

METHODS/DESIGN

RESOLVE-HCM is a prospective, multicenter double-blind placebo-controlled randomized trial enrolling symptomatic HCM patients with at least moderate LVH. Sixty patients will be randomized to receive either perhexiline or matching placebo. The primary endpoint is change in LVH, assessed utilizing cardiovascular magnetic resonance (CMR) imaging, after 12-months treatment with perhexiline.

SUMMARY

RESOLVE-HCM will provide novel information on the utility of perhexiline in regression of LVH in symptomatic HCM patients. A positive result would lead to the design of a Phase 3 clinical trial addressing long-term effects of perhexiline on risk of heart failure and mortality in HCM patients.

A mechanism of perhexiline's cytotoxicity in hepatic cells involves endoplasmic reticulum stress and p38 signaling pathway

Perhexiline is a coronary vasodilator for angina treatment that was first developed in the 1960s. Perhexiline enjoyed worldwide success before reports of severe side effects, such as hepatotoxicity and neurotoxicity, caused its withdrawal from most of the markets. The underlying mechanism of the cytotoxicity of perhexiline, however, is not yet well understood. Here we demonstrated that perhexiline induced cellular damage in primary human hepatocytes, HepaRG cells and HepG2 cells. Analysis of gene and protein expression levels of endoplasmic reticulum (ER) stress markers showed that perhexiline caused ER stress in primary human hepatocytes and HepG2 cells. The splicing of XBP1 mRNA, a hallmark of ER stress, was observed upon perhexiline treatment. Using Gluc-Fluc-HepG2 cell line, we demonstrated that protein secretion was impaired upon perhexiline treatment, suggesting functional deficits in ER. Inhibition of ER stress using ER inhibitor 4-PBA or salubrinal attenuated the cytotoxicity of perhexiline. Directly knocking down ATF4 using siRNA also partially rescued HepG2 cells upon perhexiline exposure. In addition, inhibition of ER stress using either inhibitors or siRNA transfection attenuated perhexiline-induced increase in caspase 3/7 activity, indicating that ER stress contributed to perhexiline-induced apoptosis. Moreover, perhexiline treatment resulted in activation of p38 and JNK signaling pathways, two branches of MAPK cascade. Pre-treating HepG2 cells with p38 inhibitor SB239063 attenuated perhexiline-induced apoptosis and cell death. The inhibitor also prevented the activation of CHOP and ATF4. Overall, our study demonstrated that ER stress is one important mechanism underlying the hepatotoxicity of perhexiline, and p38 signaling pathway contributes to this process. Our finding shed light on the role of both ER stress and p38 signaling pathway in drug-induced liver injury.

Comparison of CYP2D metabolism and hepatotoxicity of the myocardial metabolic agent perhexiline in Sprague-Dawley and Dark Agouti rats

1. Perhexiline, a chiral anti-anginal agent, may be useful to develop new cardiovascular therapies, despite its potential hepatotoxicity. 2. This study compared Dark Agouti (DA) and Sprague-Dawley (SD) rats, as models of perhexiline's metabolism and hepatotoxicity in humans. Rats (n = 4/group) received vehicle or 200 mg/kg/d of racemic perhexiline maleate for 8 weeks. Plasma and liver samples were collected to determine concentrations of perhexiline and its metabolites, hepatic function and histology. 3. Median (range) plasma and liver perhexiline concentrations in SD rats were 0.09 (0.04-0.13) mg/L and 5.42 (0.92-8.22) ng/mg, respectively. In comparison, DA rats showed higher (p < 0.05) plasma 0.50 (0.16-1.13) mg/L and liver 24.5 (9.40-54.7) ng/mg perhexiline concentrations, respectively, 2.5- and 3.7-fold higher cis-OH-perhexiline concentrations, respectively (p < 0.05), and lower plasma metabolic ratio (0.89 versus 1.55, p < 0.05). In both strains, the (+):(-) enantiomer ratio was 2:1. Perhexiline increased plasma LDH concentrations in DA rats (p < 0.05), but had no effect on plasma biochemistry in SD rats. Liver histology revealed lower glycogen content in perhexiline-treated SD rats (p < 0.05), but no effects on lipid content in either strain. 4. DA rats appeared more similar to humans with respect to plasma perhexiline concentrations, metabolic ratio, enantioselective disposition and biochemical changes suggestive of perhexiline-induced toxicity.

Effect of CYP2D6 metabolizer status on the disposition of the (+) and (−) enantiomers of perhexiline in patients with myocardial ischaemia

AIMS

This study investigated the effects of increasing doses of rac-perhexiline maleate and CYP2D6 phenotype and genotype on the pharmacokinetics of (+) and (-)-perhexiline.

METHODS

In a prospective study, steady-state plasma concentrations of (+) and (-)-perhexiline were quantified in 10 CYP2D6 genotyped patients following dosing with 100 mg/day rac-perhexiline maleate, and following a subsequent dosage increase to 150 or 200 mg/day. In a retrospective study, steady-state plasma concentrations of (+) and (-)-perhexiline were obtained from 111 CYP2D6 phenotyped patients receiving rac-perhexiline maleate.

RESULTS

In the prospective study, comprising one poor and nine extensive/intermediate metabolizers, the apparent oral clearance (CL/F) of both enantiomers increased with the number of functional CYP2D6 genes. In the nine extensive/intermediate metabolizers receiving the 100 mg/day dose, the median CL/F of (+)-perhexiline was lower than that of (-)-perhexiline (352.5 versus 440.6 l/day, P<0.01). Following the dosage increase, the median CL/F of both enantiomers decreased by 45.4 and 41.4%, respectively. In the retrospective study, the median (+)-/(-)-perhexiline plasma concentration ratio was lower (P<0.0001) in phenotypic extensive/intermediate (1.41) versus poor metabolizers (2.29). Median CL/F of (+) and (-)-perhexiline was 10.6 and 24.2 l/day (P<0.05), respectively, in poor metabolizers, and 184.1 and 272.0 l/day (P<0.001), respectively, in extensive/intermediate metabolizers.

CONCLUSIONS

Perhexiline's pharmacokinetics exhibit significant enantioselectivity in CYP2D6 extensive/intermediate and poor metabolizers, with both enantiomers displaying polymorphic and saturable metabolism via CYP2D6. Clinical use of rac-perhexiline may be improved by developing specific enantiomer target plasma concentration ranges.