Paradoxical high-density lipoprotein reduction induced by fibrate therapy

Paradoxical and bidirectional drug effects

A paradoxical drug reaction constitutes an outcome that is opposite from the outcome that would be expected from the drug's known actions. There are three types: 1. A paradoxical response in a condition for which the drug is being explicitly prescribed. 2. Paradoxical precipitation of a condition for which the drug is indicated, when the drug is being used for an alternative indication. 3. Effects that are paradoxical in relation to an aspect of the pharmacology of the drug but unrelated to the usual indication. In bidirectional drug reactions, a drug may produce opposite effects, either in the same or different individuals, the effects usually being different from the expected beneficial effect. Paradoxical and bidirectional drug effects can sometimes be harnessed for benefit; some may be adverse. Such reactions arise in a wide variety of drug classes. Some are common; others are reported in single case reports. Paradoxical effects are often adverse, since they are opposite the direction of the expected effect. They may complicate the assessment of adverse drug reactions, pharmacovigilance, and clinical management. Bidirectional effects may be clinically useful or adverse. From a clinical toxicological perspective, altered pharmacokinetics or pharmacodynamics in overdose may exacerbate paradoxical and bidirectional effects. Certain antidotes have paradoxical attributes, complicating management. Apparent clinical paradoxical or bidirectional effects and reactions ensue when conflicts arise at different levels in self-regulating biological systems, as complexity increases from subcellular components, such as receptors, to cells, tissues, organs, and the whole individual. These may be incompletely understood. Mechanisms of such effects include different actions at the same receptor, owing to changes with time and downstream effects; stereochemical effects; multiple receptor targets with or without associated temporal effects; antibody-mediated reactions; three-dimensional architectural constraints; pharmacokinetic competing compartment effects; disruption and non-linear effects in oscillating systems, systemic overcompensation, and other higher-level feedback mechanisms and feedback response loops at multiple levels. Here we review and provide a compendium of multiple class effects and individual reactions, relevant mechanisms, and specific clinical toxicological considerations of antibiotics, immune modulators, antineoplastic drugs, and cardiovascular, CNS, dermal, endocrine, musculoskeletal, gastrointestinal, haematological, respiratory, and psychotropic agents.

Low incidence of paradoxical reductions in HDL-C levels in dyslipidemic patients treated with fenofibrate alone or in combination with ezetimibe or ezetimibe/simvastatin

BACKGROUND

Fibrates have been reported to cause paradoxical decreases in HDL-C in certain patients.

DESIGN AND METHODS

This post-hoc analysis explored the frequency/magnitude of HDL-C reductions in a pooled database of mixed dyslipidemic patients (LDL-C:3.4-5.7 mmol/L;TG:1.7-5.7 mmol/L) receiving placebo (PBO), fenofibrate (FENO), ezetimibe plus FENO (EZE+FENO), or EZE/simvastatin plus FENO (EZE/SIMVA+FENO) for 12 weeks.

RESULTS

PBO-treated patients had the highest incidence of HDL-C reductions from baseline (45%) compared with patients taking FENO (14%), EZE+FENO (9%), or EZE/SIMVA+FENO (9%). Reductions <30% reflected natural variability since the largest reduction in HDL-C approached 30% in the PBO group. Only 3 patients exhibited HDL-C reductions ≥30% (i.e., 2 patients in the FENO group and 1 in the EZE+FENO group). There were no differences in demographic/biochemical characteristics between patients with and without HDL-C reductions.

CONCLUSIONS

The incidence of paradoxical HDL-C reductions was low in mixed dyslipidemic patients receiving FENO alone or combined with EZE or EZE/SIMVA.

Modulating effects of chlorogenic acid on lipids and glucose metabolism and expression of hepatic peroxisome proliferator-activated receptor-alpha in golden hamsters fed on high fat diet

OBJECTIVE

To examine the effects of chlorogenic acid (CGA) on lipid and glucose metabolism under a high dietary fat burden and to explore the possible role of peroxisome proliferator-activated receptor-alpha (PPAR-alpha) in these effects.

METHODS

Twenty male golden hamsters were randomly divided into CGA treatment group (n=10, given peritoneal injection of CGA solution prepared with PBS, 80 mg CGA/kg body weight daily), and control group (n=10, given PBS i.p. at the average volume of the treatment group). Animals in both groups were given 15% high fat diet. Eight weeks after treatment with CGA, the level of biochemical parameters in fasting serum and tissues and the expression of hepatic mRNA and protein PPAR-alpha were determined.

RESULTS

Eight weeks after treatment with CGA, the levels of fasting serum triglyceride (TG), free fatty acid (FFA), total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), glucose (FSG), and insulin (FSI) were significantly lower in the GGA treatment group than in the control group. CGA also led to higher activity of hepatic lipase (HL), lower contents of TG and FFA in liver, and lower activity of lipoprotein lipase (LPL) in skeletal muscle. Furthermore, CGA significantly elevated significantly elevated the expression level of mRNA and protein expression in hepatic PPAR-alpha.

CONCLUSION

CGA can modify lipids and glucose metabolism, which may be attributed to PPAR-alpha facilitated lipid clearance in liver and improved insulin sensitivity.

A paradoxical severe decrease in serum HDL-cholesterol after treatment with a fibrate

There have been a handful of reports in the literature of a paradoxical decrease in serum high density lipoprotein (HDL)-cholesterol in patients on fibrate drugs. The reason for this decline in cardioprotective HDL-cholesterol is not known and may have potential deleterious effects on the patient. This report describes a decrease in serum HDL-cholesterol in a patient on both simvastatin and bezafibrate. This patient also developed abnormal renal function, probably interstitial nephritis. In addition, the literature of fibrate induced serum HDL-cholesterol decline is reviewed and possible mechanisms for this phenomenon discussed.