Sarpogrelate reduces mechanical hemolysis in patients with heart valve prostheses

Pharmacokinetics of a new once-daily controlled-release sarpogrelate hydrochloride compared with immediate-release formulation and the effect of food

WHAT IS KNOWN AND OBJECTIVE

Sarpogrelate is a selective 5-hydroxytryptamine receptor subtype 2A antagonist that inhibits platelet aggregation and vasoconstriction. The aim of this study was to compare the pharmacokinetics of a sarpogrelate controlled-release formulation (CR) with those of the immediate-release formulation (IR). The effect of food on the pharmacokinetics of CR sarpogrelate was also evaluated.

METHODS

A randomized, open-label, 3-period, 3-treatment crossover study was conducted in 50 healthy male subjects. Subjects were allocated into one of six sequence groups. In one period, a 100-mg IR formulation was administered three times at 6-h intervals, and in the other two periods, a 300-mg CR formulation was administered once to fasting and once to fed subjects. Each period was separated by a 7-day washout period. Serial blood samples were collected up to 24 h after the first drug administration in each period. The plasma concentrations of sarpogrelate were analysed by liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated by non-compartmental methods.

RESULTS AND DISCUSSION

After the administration of the IR formulation, the plasma concentration reached a peak at 0·48 h and the drug was eliminated with a half-life (t1/2 ) of 0·7 h. After administration of the CR formulation, the plasma concentration reached a peak at 0·5 h and the drug was eliminated with a t1/2 of 3·23 h. The geometric mean ratios (CR/IR) for sarpogrelate area under the plasma concentration-time curve (AUC) and the maximum plasma drug concentration (Cmax) were 1·2040 (90% confidence interval (CI): 1·0992-1·3188) and 0·9462 (90% CI: 0·8504-1·0529). When CR was administered to fed subjects, the time to peak concentration was prolonged to 3·97 h and t1/2 was shortened to 1·45 h. The geometric mean ratios (fasting/fed) for sarpogrelate AUC and Cmax were 0·8573 (90% CI: 0·7687-0·9561) and 0·6452 (90% CI: 0·5671-0·7341).

WHAT IS NEW AND CONCLUSION

After the administration of CR and IR formulations of the same daily dose of sarpogrelate hydrochloride, the overall systemic exposure was slightly higher for the CR than for the IR formulation, whereas peak concentration was comparable between the two formulations. Food reduced the bioavailability of sarpogrelate CR.

Erythrocyte-protective effect of sarpogrelate hydrochloride (Anplag ®), a selective 5-HT2 receptor antagonist: an in vitro study

Sarpogrelate hydrochloride (Anplag(®); Mitsubishi Tanabe Pharma Corporation, Osaka, Japan) is a selective S(2)-serotonergic receptor antagonist and is used as an antiplatelet agent. Sarpogrelate has been reported to increase erythrocyte deformability and suppress shear stress-induced hemolysis. In this study, we tested the protective effect of sarpogrelate on erythrocytes in an in vitro model. We compared the normalized index of hemolysis (NIH) between the group that was treated with sarpogrelate (n = 5) and the control group (n = 5) in a mock circulation under a shear force generated by a centrifugal pump. In the former group, 300 mg/day sarpogrelate was orally administered to a human volunteer for 2 days before blood collection. The NIH was significantly lower in the sarpogrelate group than it was in the control group (0.0012 ± 0.0009 vs. 0.0027 ± 0.0005 g/100 l, respectively; p = 0.016). Sarpogrelate suppressed shear stress-induced hemolysis in an in vitro model suggesting that sarpogrelate has a protective effect on erythrocytes under mechanical shear stress.

[Hemolytic anemia following mitral valve surgery]

Mitral valvuloplasty which is currently the most popular surgical procedure in MVD may be complicated mostly by restenosis or valvular leakage. Hemolysis occurs less frequently and by far less commonly than in prosthetic valves but deserves to be known. Delay between valvuloplasty and hemolytic anemia occurrence may vary within a wide range (from some weeks to several years as in the case we report here). A careful follow-up of the patients who undergo MV repair will help to identify this complication which is related not to the size of the regurgitation flow but to the velocity of the jet. Surgery is the unique treatment of this kind of anemia.

Functions of 5-HT2A receptor and its antagonists in the cardiovascular system

The serotonin (5-hydroxytryptamine, 5-HT) receptors have conventionally been divided into seven subfamilies, most of which have several subtypes. Among them, 5-HT(2A) receptor is associated with the contraction of vascular smooth muscle, platelet aggregation and thrombus formation and coronary artery spasms. Accordingly, selective 5-HT(2A) antagonists may have potential in the treatment of cardiovascular diseases. Sarpogrelate, a selective 5-HT(2A) antagonist, has been introduced clinically as a therapeutic agent for the treatment of ischemic diseases associated with thrombosis. Molecular modeling studies also suggest that sarpogrelate is a 5-HT(2A) selective antagonist and is likely to have pharmacological effects beneficial in the treatment of cardiovascular diseases. This review describes the above findings as well as the signaling linkages of the 5-HT(2A) receptors and the mode of agonist binding to 5-HT(2A) receptor using data derived from molecular modeling and site-directed mutagenesis.