Effectiveness and safety of laropiprant on niacin-induced flushing

Efficacy of Laropiprant in Minimizing Brain Injury Following Experimental Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is one of the most devastating and disabling forms of stroke, yet effective treatments are still lacking. Prostaglandins and their receptors have been implicated in playing vital roles in ICH outcomes. Recently, laropiprant, a DP1 receptor antagonist, has been used in combination with niacin to abolish the prostaglandin D2-(PGD2)-induced flushing. Here, we test the hypothesis that laropiprant limits bleeding and rescues the brain from ICH. Wildtype (WT) and DP1-/- mice were subjected ICH and neurologic deficits and hemorrhagic lesion outcomes were evaluated at 72 hours after the ICH. To test the therapeutic potential of laropiprant, WT mice subjected to ICH were treated with laropiprant at 1 hour after the ICH. The putative effect of laropiprant on limiting hematoma expansion was tested by an in vivo tail bleeding cessation method and an ex vivo coagulation method. Finally, the roles of laropiprant on gliosis and iron accumulation were also investigated. A significant decrease in the injury volume was observed in DP1-/- as well as laropiprant-treated WT mice. The tail bleeding time was significantly lower in laropiprant group as compared with the vehicle group. Significantly lower Iba-1 and Perls' iron staining in DP1-/- and laropiprant-treated WT groups were observed. Altogether, the data suggest that laropiprant treatment post-ICH attenuates brain damage by targeting primary as well as secondary injuries.

Pharmacogenetics of cutaneous flushing response to niacin/laropiprant combination in Hong Kong Chinese patients with dyslipidemia

AIM

Cutaneous flushing with niacin varies between individuals and is substantially reduced by concomitant laropiprant. We investigated associations between baseline phenotypes and selected genotypes and flushing symptoms with niacin/laropiprant combination.

PATIENTS & METHODS

Flushing symptoms were quantified in 196 Chinese dyslipidaemic patients treated with niacin/laropiprant, and associations with phenotypes and selected polymorphisms were analyzed.

RESULTS

Moderate or severe flushing was associated with lower body mass index and the rs2279238 polymorphism in the LXRα on multivariate regression analysis and these factors accounted for 18.9% of the total variance.

CONCLUSION

Lower body mass index and the LXRα polymorphism appear to be associated with flushing symptoms with niacin/laropiprant. Whether these findings can be applicable to other niacin formulations without laropiprant needs to be verified.

Effects of formulation design on niacin therapeutics: mechanism of action, metabolism, and drug delivery

Niacin is a highly effective, lipid regulating drug associated with a number of metabolically induced side effects such as prostaglandin (PG) mediated flushing and hepatic toxicity. In an attempt to reduce the development of these adverse effects, scientists have investigated differing methods of niacin delivery designed to control drug release and alter metabolism. However, despite successful formulation of various orally based capsule and tablet delivery systems, patient adherence to niacin therapy is still compromised by adverse events such as PG-induced flushing. While the primary advantage of orally dosed formulations is ease of use, alternative delivery options such as transdermal delivery or polymeric micro/nanoparticle encapsulation for oral administration have shown promise in niacin reformulation. However, the effectiveness of these alternative delivery options in reducing inimical effects of niacin and maintaining drug efficacy is still largely unknown and requires more in-depth investigation. In this paper, we present an overview of niacin applications, its metabolic pathways, and current drug delivery formulations. Focus is placed on oral immediate, sustained, and extended release niacin delivery as well as combined statin and/or prostaglandin antagonist niacin formulation. We also examine and discuss current findings involving transdermal niacin formulations and polymeric micro/nanoparticle encapsulated niacin delivery.

Niacin as antidyslipidemic drug

Niacin is an important vitamin (B3) that can be used in gram doses to positively modify pathogenetically relevant lipid disorders: elevated LDL cholesterol, elevated non-HDL cholesterol, elevated triglycerides, elevated lipoprotein(a), and reduced HDL cholesterol. This review reports the latest published findings with respect to niacin's mechanisms of action on these lipids and its anti-inflammatory and anti-atherosclerotic effects. In the pre-statin era, niacin was shown to have beneficial effects on cardiovascular end-points; but in recent years, two major studies performed in patients whose LDL cholesterol levels had been optimized by a statin therapy did not demonstrate an additional significant effect on these end-points in the groups where niacin was administered. Both studies have several drawbacks that suggest that they are not representative for other patients. Thus, niacin still plays a role either as an additive to a statin or as a substitute for a statin in statin-intolerant patients. Moreover, patients with elevated triglyceride and low HDL cholesterol levels and patients with elevated lipoprotein(a) concentrations will possibly benefit from niacin, although currently the study evidence for these indications is rather poor. Niacin may be useful for compliant patients, however possible side effects (flushing, liver damage) and contraindications should be taken into consideration.

Safety and tolerability of extended-release niacin-laropiprant: Pooled analyses for 11,310 patients in 12 controlled clinical trials

BACKGROUND

The Heart Protection Study 2-Treatment of HDL to Reduce the Incidence of Vascular Events (HPS2-THRIVE) showed that adding extended-release niacin-laropiprant (ERN-LRPT) to statin provided no incremental cardiovascular benefit vs placebo (PBO). ERN-LRPT was also associated with an excess of serious adverse experiences (AEs), some of which were unexpected (infections and bleeding). These findings led to the withdrawal of ERN-LRPT from all markets.

OBJECTIVE

We examined the safety profile of ERN-LRPT vs the comparators ERN alone and statins in the ERN-LRPT development program to assess whether similar safety signals were observed to those seen in HPS-THRIVE and whether these might be attributed to ERN or LRPT.

METHODS

Postrandomization safety data from 12 clinical studies, 12 to 52 weeks in duration and involving 11,310 patients, were analyzed across 3 treatments: (1) ERN-LRPT; (2) ERN-NSP (ERN, Merck & Co, Inc or Niaspan [NSP], Abbott Laboratories); and (3) statin-PBO (statin or PBO).

RESULTS

The safety profiles of ERN-LRPT and ERN-NSP were similar, except for less flushing with ERN-LRPT. Nonflushing AEs reported more frequently with ERN-LRPT or ERN-NSP than with statin-PBO were mostly nonserious and typical of niacin (nausea, diarrhea, and increased blood glucose). There was no evidence for an increased risk of serious AEs related to diabetes, muscle, infection, or bleeding.

CONCLUSIONS

Pooled data from 11,310 patients revealed that, except for reduced flushing, the safety profile of ERN-LRPT was similar to that of ERN-NSP; LRPT did not appear to adversely affect the side-effect profile of ERN. The inability to replicate the unexpected AE findings in HPS2-THRIVE could be because of the smaller sample size and substantially shorter duration of these studies.

Benefits and harm of niacin and its analog for renal dialysis patients: a systematic review and meta-analysis

PURPOSE

Clinical trials have shown that niacin and its analog, niacinamide, significantly reduce serum phosphate in patients undergoing dialysis. This review aimed to assess the benefits and harm of niacin and niacinamide in renal dialysis patients.

METHODS

PubMed, EMBASE, and Cochrane Library were searched, without language limitation, randomized controlled trials (RCTs). Standard methods, consistent with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, were used. Reviewer Manager software, version 5.2, was used for meta-analysis.

RESULTS

Five RCTs with a sample size of 230 patients were included. The meta-analysis showed that niacin and niacinamide significantly decreased serum phosphorus levels [weight mean difference (WMD) -0.88; 95 % confidence interval (CI) -1.19 to -0.57] as well as the calcium × phosphorus product (Ca × P) (WMD -9.15; 95 % CI -13.23 to -5.08), and increased high-density lipoprotein (HDL) levels (WMD 9.30; 95 % CI 5.86-12.74) in renal dialysis patients. Niacin significantly increased the risk of flushing [relative risk (RR) 33; 95 % CI 4.71-232.12] in these patients, while the risk of thrombocytopenia was significantly increased in the niacinamide group (RR 2.82; 95 % CI 1.14-6.94). However, sensitivity analysis showed that our finding regarding thrombocytopenia should be regarded with a low degree of certainty.

CONCLUSION

Niacin and its analog effectively improved phosphorus metabolism in renal dialysis patients. However, niacin can cause flushing and niacinamide probably cause thrombocytopenia. Further larger sample size and well-designed RCTs are needed.

Apple pectin for the reduction of niacin-induced flushing

BACKGROUND

Niacin, or vitamin B3, when used in high doses can significantly improve the levels of all major lipoproteins. Despite these benefits, the use of niacin is greatly limited secondary to benign yet bothersome cutaneous flushing primarily involving the face and upper extremities. Pretreatment with aspirin or other prostaglandin inhibitors has demonstrated significant reductions in niacin-induced flushing (NIF), but other treatment options are needed. Clinical and anecdotal evidence suggests the ingestion of pectin-containing fruits (eg, apple) mitigates NIF; however, clinical trials evaluating this are nonexistent.

OBJECTIVE

That pretreatment with encapsulated apple pectin would limit the incidence, severity, time of initiation, and duration of NIF.

METHODS

We enrolled 100 niacin-naïve subjects (n = 25 per group) and preteated them in a double-blind manner with apple pectin, apple pectin + aspirin, aspirin, or placebo, followed by a one-time 1000 mg dose of niacin extended-release (niacin ER). Subjects then assessed major flushing parameters hourly for the next 6 hours with a validated visual analog scale.

RESULTS

Apple pectin and aspirin each significantly lowered the duration of NIF and produced nonsignificant but positive improvements in all other major flushing parameters compared with placebo.

CONCLUSION

Apple pectin may potentially be an alternative to aspirin for the prevention of NIF. Larger trials are needed to further evaluate the benefit of pectin on NIF.