Development of propofol-loaded microemulsion systems for parenteral delivery

Development and evaluation of camptothecin loaded polymer stabilized nanoemulsion: Targeting potential in 4T1-breast tumour xenograft model

Targeted delivery of anticancer agents is poised to improve cancer therapy, for which polymers can serve as targeting ligands or nanocarriers for chemotherapeutic agents. In this study, we have developed and evaluated the efficacy of a camptothecin (CPT)-loaded polymer stabilized nanoemulsion (PSNE) for the passive targeted delivery to breast cancer. Based on the pseudo-ternary phase diagrams, PSNEs were developed using capmul MCM:poloxamer 407 (4:1), solutol HS 15:simulsol P23 (1:2) and water. CPT polymer mixture was developed by solvent evaporation technique. The PSNEs were characterized for droplet size distribution, plasma protein adsorption, drug release, in-vivo targeting potential, hemolytic potential, cytotoxicity, genotoxicity, in-vivo biodistribution and CPT lactone ring stability. The developed PSNEs showed uniform droplet distribution, extended drug release (76.59±6.12% at 24h), acceptable hemolytic potential, significant cytotoxicity (IC₅₀=176±4.3ng/mL) and genotoxicity against MCF-7 cancer cells but low DNA damage potential in human peripheral blood lymphocytes. The efficiency of PSNEs for the targeted delivery of CPT into the tumour regions was documented in 4T1-breast tumour xenografted BALB/c mice. In-vivo biodistribution study shows that 7105.84±568.46ng/g of CPT was passively targeted from PSNE to breast cancer tissue. About 80% of the lactone form was stable for 24h. Taken together, our study provides a promising strategy for developing PSNE-targeted drug delivery system for the breast cancer therapy.

Simultaneous determination of kolliphor HS15 and miglyol 812 in microemulsion formulation by ultra-high performance liquid chromatography coupled with nano quantity analyte detector

A novel method for simultaneous determination of kolliphor HS15 and miglyol 812 in microemulsion formulation was developed using ultra-high performance liquid chromatography coupled with a nano quantitation analytical detector (UHPLC–NQAD). All components in kolliphor HS15 and miglyol 812 were well separated on an Acquity BEH C₁₈ column. Mobile phase A was 0.1% trifluoroacetic acid (TFA) in water and mobile phase B was acetonitrile. A gradient elution sequence was programed initially with 60% organic solvent, slowly increased to 100% within 8 min. The flow rate was 0.7 mL/min. Good linearity (r>0.95) was obtained in the range of 27.6–1381.1 μg/mL for polyoxyl 15 hydroxystearate in kolliphor HS15, 0.8–202.0 μg/mL for caprylic acid triglyceride and 2.7–221.9 μg/mL for capric acid triglyceride in miglyol 812. The relative standard deviations (RSD) ranged from 0.6% to 1.7% for intra-day precision and from 0.4% to 2.7% for inter-day precision. The overall recoveries (accuracy) were 99.7%–101.4% for polyoxyl 15 hydroxystearate in kolliphor HS15, 96.7%–99.6% for caprylic acid triglyceride, and 94.1%–103.3% for capric acid triglyceride in miglyol 812. Quantification limits (QL) were determined as 27.6 μg/mL for polyoxyl 15 hydroxystearate in kolliphor HS15, 0.8 μg/mL for caprylic acid triglyceride, and 2.7 μg/mL for capric acid triglyceride in miglyol 812. No interferences were observed in the retention time ranges of kolliphor HS15 and miglyol 812. The method was validated in terms of specificity, linearity, precision, accuracy, QL, and robustness. The proposed method has been applied to microemulsion formulation analyses with good recoveries (82.2%–103.4%).

"Micro to macro (M2M)"--A novel approach for intravenous delivery of propofol

PURPOSE

Propofol emulsions have limited shelf life and safety concerns for injection. Microemulsions of propofol are thermodynamically stable and simpler to manufacture, but cause additional pain on injection. We propose a novel micro to macro (M2M) approach of destabilizing a microemulsion immediately prior to injection.

METHODS

Microemulsions of propofol were prepared at two to three times the drug loadings of commercial formulations. We determined suitable microemulsion compositions which destabilize into macroemulsions after two or three fold dilutions with water. Droplet growth after dilution was measured with dynamic light scattering. Increasing solution turbidity after dilution was also measured optically with millisecond resolution. Experimental data was analyzed in the context of a coalescence model.

RESULTS

Microemulsions rapidly coalesce into larger droplet size macroemulsions after dilution according to the phase diagram shift. The resulting macroemulsions are metastable retaining their droplet size for several hours. Droplet growth occurs on the order of seconds and a metastable size of about 1 micron is reached in minutes. Rates of droplet growth and metastable droplet sizes depend on the surfactant composition. The coalescence model predicts droplet growth with good agreement but only after accounting for the finite probability of coalescence from each collision.

CONCLUSIONS

The M2M concept has been demonstrated for the anesthetic drug propofol which may improve stability and manufacturability in addition to reducing pain on injection. This approach could be adapted to other hydrophobic vesicant drugs as well.

Thromboelastographic and pharmacokinetic profiles of micro- and macro-emulsions of propofol in swine

PURPOSE

Compared with traditional macroemulsion propofol formulations currently in clinical use, microemulsion formulations of this common intravenous anesthetic may offer advantages. The pharmacokinetics and coagulation effects as assessed by thromboelastography of these formulations were characterized in swine.

METHODS

Yorkshire swine (20-30 kg, either sex, n=15) were sedated, anesthetized with isoflurane, and instrumented to obtain a tracheostomy, internal jugular access and carotid artery catheterization. Propofol (2 mg/kg, 30 s) was administered as a macroemulsion (10 mg/ml; Diprivan; n=7) or a custom (2 mg/kg, 30 s) microemulsion (10 mg/ml; n=8). Arterial blood specimens acquired pre- and post-injection (1 and 45 min) were used for thromboelastography. Arterial blood specimens (n=12 samples/subject, 60 min) were serially collected, centrifuged and analysed with solid-phase extraction with UPLC to determine propofol plasma concentrations. Non-compartmental pharmacokinetic analysis was applied to plasma concentrations.

RESULTS

No changes were noted in the thromboelastographic R time (p=0.74), K time (p=0.41), alpha angle (p=0.97), or maximal amplitude (p=0.71) for either propofol preparation. Pharmacokinetic parameters k (p=0.45), t(1/2) (p=0.26), C(o) (p=0.89), AUC(0-infinity) (p=0.23), CL (p=0.14), MRT (p=0.47), V(ss) (p=0.11) of the two formulations were not significantly different.

CONCLUSION

The microemulsion and macroemulsion propofol formulations had similar pharmacokinetics and did not modify thromboelastographic parameters in swine.

Biocompatible microemulsions and their prospective uses in drug delivery

Efficacy of lipophilic drugs is often hindered due to their poor aqueous solubility leading to low absorption after in vivo administration. A part of the administered dose is absorbed and reaches the pharmacological site of action and the remainder causes toxicity and undesirable side effects due to unwanted biodistribution. Enhancement in drug efficacy and lowering of drug toxicity could be achieved through encapsulation and delivery of the lipophilic drugs in aqueous based delivery systems. Microemulsions are macroscopically homogeneous pseudoternary and ternary colloidal assemblies having polar and nonpolar micro domains. Their dispersed phases in nanodimension have good shelf-life (due to thermodynamic stability), large surface area, low viscosity (in some compositions), and ultraslow surface tension. These properties qualify them to be prospective drug delivery systems provided they are composed of biocompatible excipients. Due to the existence of polar, nonpolar, and interfacial microdomains, encapsulation of different kinds of drugs is possible. The review entails reports on development and characterization of biocompatible microemulsion systems and their evaluation as probable vehicles for encapsulation, stabilization, and delivery of bioactive natural products and prescription drugs.

Design and evaluation of microemulsions for improved parenteral delivery of propofol

The objective of this investigation was to evaluate the potential of the microemulsions to improve the parenteral delivery of propofol. Pseudo-ternary phase diagrams were plotted to identify microemulsification region of propofol. The propofol microemulsions were evaluated for globule size, physical and chemical stability, osmolarity, in vitro hemolysis, pain caused by injection using rat paw-lick test and in vivo anesthetic activity. The microemulsions exhibited globule size less than 25 nm and demonstrated good physical and chemical stability. Propofol microemulsions were slightly hypertonic and resulted in less than 1% hemolysis after 2 h of storage with human blood at 37 degrees C. Rat paw-lick test indicated that propofol microemulsions were significantly less painful as compared to the marketed propofol formulation. The anesthetic activity of the microemulsions was similar to the marketed propofol formulation indicating that they do not compromise the pharmacological action of propofol. The stability studies indicated that the microemulsions were stable for 3 months when stored at 5 +/- 3 degrees C. Thus, microemulsions appeared to be an interesting alternative to the current propofol formulations.

Formulation of parenteral microemulsion containing itraconazole

The aim of this study was to develop an aqueous parenteral formulation containing itraconazole (ITZ) using an o/w microemulsion system. A mixture of benzyl alcohol and medium chain triglyceride (3/1) was chosen as the oil phase. Pseudoternary phase diagrams of the microemulsion formations were constructed in order to determine the optimum ratio of oils, the concentration range of surfactant and cosurfactant and the optimum ratio between them. Consequently, the suitability of the chosen microemulsion system as a parenteral formulation was evaluated using droplet size analysis and hemolysis tests. Among the surfactants and cosurfactants screened, a mixture of polyoxyethylene (50) hydrogenated castor oil and ethanol (3/1) showed the largest o/w microemulsion region in the phase diagram. The average droplet size of the microemulsions was < 150 nm, and the hemolysis test showed this formulation to be nontoxic to red blood cells. The pharmacokinetic profiles of the ITZ-microemulsion for itraconazole and its major metabolite, hydroxyitraconazole, were compared with those of a PEG 400 solution and cyclodextrin formulations in rats. Overall, these results highlight the potential of an ITZ-microemulsion formulation for the parenteral route.