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Design of cationic nanostructured heterolipid matrices for ocular delivery of methazolamide.

Youshia J, Kamel AO, El Shamy A, Mansour S - Int J Nanomedicine (2012)

Bottom Line: Solid lipid nanoparticles (SLNs) formulated from one type of lipid (homolipid) suffer from low drug encapsulation and drug bursting due to crystallization of the lipid into the more ordered β modification, which leads to decreased drug entrapment and faster drug release.The results showed that increasing the ratio of CSA to Compritol increased the EE% and PS, while increasing the concentration of Tween 80, decreased PS with no significant effect on EE%.The ZP values of all formulae were positive, and greater than 30 mV.

View Article: PubMed Central - PubMed

Affiliation: Pharmaceutics and Industrial Pharmacy Department, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt.

ABSTRACT
Solid lipid nanoparticles (SLNs) formulated from one type of lipid (homolipid) suffer from low drug encapsulation and drug bursting due to crystallization of the lipid into the more ordered β modification, which leads to decreased drug entrapment and faster drug release. This study assessed the feasibility of using nanostructured lipid matrices (NLMs) for ocular delivery of methazolamide-(MZA) adopting heterolipids composed of novel mixtures of Compritol (®) and cetostearyl alcohol (CSA), and stabilized by Tween 80(®). The systems were prepared using the modified high shear homogenization followed by ultrasonication method, which avoids the use of organic solvents. A 3(2) full factorial design was constructed to study the influence of two independent variables, namely the ratio of CSA:Compritol and the concentration of Tween 80, each in three levels. The dependent variables were the entrapment efficiency percentages (EE%), mean particle size (PS), polydispersity index (PDI), and zeta potential (ZP). In vivo intraocular pressure (IOP) lowering activity for the selected formulae was compared to that of MZA solution. The results showed that increasing the ratio of CSA to Compritol increased the EE% and PS, while increasing the concentration of Tween 80, decreased PS with no significant effect on EE%. The ZP values of all formulae were positive, and greater than 30 mV. The best formula, composed of 4% CSA, 2% Compritol, 0.15% stearylamine, and 2% Tween 80, with EE% of 25.62%, PS of 207.1 nm, PDI of 0.243, and ZP of 41.50 mV, showed in vitro sustained release properties for 8 hours and lowered the intraocular pressure by 8.3 mmHg within 3 hours, with this drop in pressure lasting for 12 hours.

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Change in mean PS of MZA-loaded NLMs after refrigeration for 1 month at 4°C.Abbreviations: MZA, methazolamide; NLM, nanostructured lipid matrix.
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f9-ijn-7-2483: Change in mean PS of MZA-loaded NLMs after refrigeration for 1 month at 4°C.Abbreviations: MZA, methazolamide; NLM, nanostructured lipid matrix.

Mentions: To assess the effect of aging on the prepared NLMs, mean PS was measured following one month of refrigeration; the results of this are presented in Figure 9. Student’s t-test analysis demonstrated that formulae NLM-1 and NLM-3 containing 0.5 wt% Tween 80 and formulae NLM-4 and NLM-5 containing 1 wt% Tween 80 showed significant change in mean PS (P < 0.01). However, all formulae were stable at 2 wt% Tween 80, with no significant change in mean PS. This indicates that a higher concentration of Tween 80 leads to very high stability. As a general conclusion, NLMs showed very good stability after 1 month, with the mean PS of all formulae remaining below 500 nm (including those that showed a significant increase in PS). This may be attributed to the high positive charge induced by the presence of stearylamine, which would be expected to cause repulsion between particles, so avoiding their aggregation and coalescence, in addition to the stabilizing effect of Tween 80.


Design of cationic nanostructured heterolipid matrices for ocular delivery of methazolamide.

Youshia J, Kamel AO, El Shamy A, Mansour S - Int J Nanomedicine (2012)

Change in mean PS of MZA-loaded NLMs after refrigeration for 1 month at 4°C.Abbreviations: MZA, methazolamide; NLM, nanostructured lipid matrix.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3367493&req=5

f9-ijn-7-2483: Change in mean PS of MZA-loaded NLMs after refrigeration for 1 month at 4°C.Abbreviations: MZA, methazolamide; NLM, nanostructured lipid matrix.
Mentions: To assess the effect of aging on the prepared NLMs, mean PS was measured following one month of refrigeration; the results of this are presented in Figure 9. Student’s t-test analysis demonstrated that formulae NLM-1 and NLM-3 containing 0.5 wt% Tween 80 and formulae NLM-4 and NLM-5 containing 1 wt% Tween 80 showed significant change in mean PS (P < 0.01). However, all formulae were stable at 2 wt% Tween 80, with no significant change in mean PS. This indicates that a higher concentration of Tween 80 leads to very high stability. As a general conclusion, NLMs showed very good stability after 1 month, with the mean PS of all formulae remaining below 500 nm (including those that showed a significant increase in PS). This may be attributed to the high positive charge induced by the presence of stearylamine, which would be expected to cause repulsion between particles, so avoiding their aggregation and coalescence, in addition to the stabilizing effect of Tween 80.

Bottom Line: Solid lipid nanoparticles (SLNs) formulated from one type of lipid (homolipid) suffer from low drug encapsulation and drug bursting due to crystallization of the lipid into the more ordered β modification, which leads to decreased drug entrapment and faster drug release.The results showed that increasing the ratio of CSA to Compritol increased the EE% and PS, while increasing the concentration of Tween 80, decreased PS with no significant effect on EE%.The ZP values of all formulae were positive, and greater than 30 mV.

View Article: PubMed Central - PubMed

Affiliation: Pharmaceutics and Industrial Pharmacy Department, Faculty of Pharmacy, Ain Shams University, Cairo, Egypt.

ABSTRACT
Solid lipid nanoparticles (SLNs) formulated from one type of lipid (homolipid) suffer from low drug encapsulation and drug bursting due to crystallization of the lipid into the more ordered β modification, which leads to decreased drug entrapment and faster drug release. This study assessed the feasibility of using nanostructured lipid matrices (NLMs) for ocular delivery of methazolamide-(MZA) adopting heterolipids composed of novel mixtures of Compritol (®) and cetostearyl alcohol (CSA), and stabilized by Tween 80(®). The systems were prepared using the modified high shear homogenization followed by ultrasonication method, which avoids the use of organic solvents. A 3(2) full factorial design was constructed to study the influence of two independent variables, namely the ratio of CSA:Compritol and the concentration of Tween 80, each in three levels. The dependent variables were the entrapment efficiency percentages (EE%), mean particle size (PS), polydispersity index (PDI), and zeta potential (ZP). In vivo intraocular pressure (IOP) lowering activity for the selected formulae was compared to that of MZA solution. The results showed that increasing the ratio of CSA to Compritol increased the EE% and PS, while increasing the concentration of Tween 80, decreased PS with no significant effect on EE%. The ZP values of all formulae were positive, and greater than 30 mV. The best formula, composed of 4% CSA, 2% Compritol, 0.15% stearylamine, and 2% Tween 80, with EE% of 25.62%, PS of 207.1 nm, PDI of 0.243, and ZP of 41.50 mV, showed in vitro sustained release properties for 8 hours and lowered the intraocular pressure by 8.3 mmHg within 3 hours, with this drop in pressure lasting for 12 hours.

Show MeSH
Related in: MedlinePlus