Effect of lipid excipients on in vitro pancreatic lipase activity

Purpose. To study the effects of two lipid excipients. Pecel(R) and Gelucire 44/14((R)) on the in vitro pancreatic lipase activity. Methods. A 50muL reaction mixture. consisting of 45 muL (H-3) triolein as the radiolabeled substrate, 2.5 muL Peceol or Gelucire 44/14 (0.05-0.5%), either alone or in combination, 2.5muL colipase (100mug/mL), and 2.5muL pancreatic lipase (1 mg/mL), was incubated for 10 min at room temperature. At the end of incubation, the reaction was stopped by the addition of an extraction solvent containing chloroform, methanol, and n-heptane (12.5:14:10), and the mixture vortxed briefly. Subsequently, 250 muL of 50 mM sodium carbonate was Lidded and the aqueous and organic phase separated by centrifugation for 5 min Lit 1000 g. One hundred microliters of the supernatant was transferred to a scintillation counter and then radioactivity measured after the addition of 3.6 mL of scintillation fluid. Pancreatic lipase activity was determined by measuring the amount of free fatty acid released into the incubation medium and expressed as mumol free fatty acid released/min. Results. When used alone, Peceol inhibited the pancreatic lipase activity significantly in a concentration-dependent manner, with a maximum inhibition of 57% at 0.4% of the excipient [p<0.05, one-way analysis of variance (ANOVA)]. Similarly, Gelucire 44/14 alone caused inhibition of lipase activity in a concentration-dependent manner. However, the maximum inhibition (30%) was smaller in magnitude compared with the former agent. When the two excipients were used in combination, the inhibitory effects on the enzyme activity were similar to those observed with the individual agents (p<0.05, one-way ANOVA). However, the maximum inhibition of 30% was lower than that observed with Peceol alone. Conclusions. The results from this Study suggest that these lipid excipients inhibit in vitro pancreatic lipase activity and should be taken into consideration when developing oral formulations using these agents.