Formulation and Optimization of Self Emulsifying Drug Delivery System For Effective Anthelmintic Therapy

 

Kiran C. Mahajan¹*, Dr. Smita S. Pimple², Hemant A. Deokule³

Department of Pharmaceutics, Progressive Education Society’s Modern College of Pharmacy, Nigdi-411044, Dist.-Pune, Maharashtra, India.

 

ABSTRACT:

The present study aims to develop and optimize a self-emulsifying drug delivery system for paediatric patients to improve the oral bioavailability of the anthelmintic drug, Praziquantel (PZQ) and to perform it’s in-vitro dissolution study. The solubility of PZQ was estimated in various vehicles to select proper component combination. Capmul MCM (oil), Cremophore RH40 (surfactant) and PEG400 (co-surfactant) were employed to construct pseudo-ternary phase diagrams. Eight formulations composed of Capmul MCM, at Smix ratios (1:1, 2:1 & 3:1) were selected. The optimized formulation F7 has a mean globule size 14.73 nm with a negative zeta potential -44.43 mV. The results indicated that PZQ loaded SEDDS, showed enhanced solubilization and nanosizing potential to improve the absorption of the drug.

 

 

INTRODUCTION:

The oral route has been a major route of drug delivery for the treatment of various diseases. The delivery of poorly water-soluble molecules by the oral route is difficult because approximately 40% of drug compounds are limited to low aqueous solubility, which leads to restricted oral bioavailability and lack of dose proportionality. Recently so much attention has been focused on self-emulsifying drug delivery systems (SEDDS) to improve the oral bioavailability of the poorly water-soluble drugs.^[1,2]

 

Anthelmintic drugs are used for the treatment of worm’s infections. Praziquantel works by causing severe spasms and paralysis of the worm’s muscles. This paralysis is accompanied and probably caused by a rapid Ca²⁺ influx inside the schistosome. Praziquantel is an anthelmintic drug used in schistosome, tapeworm infections and other fluke infections.^[3,4]  Praziquantel is freely soluble in methanol & in dichloromethane.^[5]  In 2010, WHO recommended that the inclusion of preschool-aged children in large scale treatment programmes.

 

Praziquantel is the drug of choice for treatment of infections with all schistosoma species.^[6] There are certain issues while administrating existing paediatric dosage forms like dose adjustment, swallowing and less stability of dosage forms is a challenging process in small children’s. So that there is a need to develop a special paediatric dosage form which can be administered without any difficulty. This research project is mainly focused on the development of a PZQ loaded SEDDS suitable for the oral administration to the paediatric patients.

 

MATERIALS AND METHODS:

Materials:

PZQ was kindly donated by Microlab Pvt. Ltd, Goa. Capmul MCM was obtained from Abitech Corporation, U.S.A., Cremophore RH40 was procured from BASF, Mumbai & PEG 400 was obtained from Pure Chem. Lab, Pune. All other chemicals were of analytical grade.

 

Methods:

Solubility study:

The solubility of PZQ in various oils (Capmul MCM, Capryol 90, Oleic acid, Arachis oil, Captex 300, Castor oil, Soyabean oil, Isopropyl myristate, Labrafil, Olive oil & Almond oil), surfactants (Cremophore RH 40, Tweens 80, Tweens 20 & Span 20) and co-surfactants (PEG 400, Transcutol & Propylene glycol) was determined. In a vial, 2 ml of required solvent and excess quantity of the drug was added. The equilibrated mixture was removed, filtrate and analyze by using a UV-Visible spectrophotometer (JASCO V-630). All measurements were done in triplicates.^[7,8,9]

 

Preliminary screening of surfactants:

The surfactant to oil in a ratio of 1:1 was mixed (300 mg of the surfactants, Cremophore RH 40, Tweens 80, Tweens 20 & Span 20 were added to 300 mg of the oily phase) and their % transmittance was evaluated at 638.2 nm by using UV-spectrophotometer (JASCO V-630). These emulsions were furthermore observed visually for any turbidity or phase separation.^[10,11]

 

Preliminary screening of co-surfactants:

The selected oily phase and surfactants were used for further screening of the different co-surfactants for their emulsification ability in a ratio of 3:2:1 of oil, surfactant and co-surfactant respectively (it gives 1:1 ratio of Oil to S/Comix). Mixtures of 300 mg oil, 200 mg surfactant and 100 mg of co-surfactant were prepared and evaluated similarly as above.

 

Construction of pseudo-ternary phase diagram:

The pseudo-ternary phase diagrams were constructed by using water titration method. For any mixture, the total of surfactant, co-surfactant and oil concentrations always added to 100%. At desired (ratio of surfactant to co-surfactant) value (1:1, 2:1, 3:1 and 1:2), Smix and oil were mixed at ratio of 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2 and 9:1 in pre-weighed vial. To the resultant mixtures, water was added dropwise till it forms clear or slightly bluish appearance and easily flowable o/w microemulsions. The slightly less clear system, which had a bluish-white or bright white appearance, was defined as an emulsion. After identifying the highest microemulsion region at desired Smix value, that value was put in Design-Expert software version 8 (Stat-Ease, Inc., Minneapolis, MN, trial version) to prepare liquid SEDDS. The phase diagram was constructed by using Central Composite Design software (MN, USA, Trial version).^[12,13,14]

 

Preparation of liquid self-emulsifying formulation loaded with Praziquantel by using central composite design:

Accurately weighed Praziquantel and the selected excipients such as Capmul MCM, Cremophor RH 40 and PEG 400 were added to the vial and mixed by using a magnetic stirrer for 15 min.  Further, the formulations were warmed on a water bath at 40°C to help in solubilization. The formulations were observed for isotropicity and were stored at room temperature until further analysis.^[15,16]

 

Characterization of formulations^[17-25]:

X-ray diffraction (XRD) analysis:

X-ray diffraction (XRD) studies were studied by using X-ray diffractometer with Cu-K𝛼 radiation (Voltage 40 kV and the current 30 mA). The scanning angle ranged from 5 to 25° of 2θ.

 

Transmittance test:

The stability of SEDDS formulation on dilution was checked measuring the transmittance by using a UV-visible spectrophotometer.  The transmittance of each sample was measured at 638.2 nm.

 

Determination of self-emulsification time:

A quantity of 1ml of each formulation was added to 900 ml of distilled water under continuous stirring (50 rpm) using USP dissolution test apparatus II at 37 ± 0.5ºC. The time required to disperse the system completely and uniformly was determined and the emulsification time was recorded in seconds.

 

Cloud point measurement:

Each formulation was diluted with distilled water in the ratio of 1:250 and placed in a water bath with a gradual increase in temperature. The point at which cloudiness occurs was noted as a cloud point.

 

Globule size determination:

Mean globule size and the polydispersity index of the resulting emulsions were determined by using photon correlation spectroscopy (Nanophox, Sympatec, Germany). The sample temperature was set at 25°C and detection was carried out at a scattering angle of 90°.

 

Determination of zeta potential:

The zeta potential was measured by using photon correlation spectroscopy.

 

Determination of drug content:

Self-emulsifying formulations were dissolved in methanol. Then solution was filtered and determined the absorbance on UV-Visible spectrophotometer by using diluted self-emulsifying formulation without drug as a blank at 263 nm.

 

In-vitro dissolution studies:

In-vitro release test was performed in 900 mL (0.1N HCl) is maintained at 37 ± 0.5°C using USP type-II dissolution test apparatus. 5 ml aliquots were collected periodically (2, 5, 10, 15, 20, 25, 30, 45 and 60 min.) and replaced with fresh dissolution medium. After filtration through 0.45 μm pore- sized membrane filter, analysis was carried out by using UV-Visible spectrophotometer at 263 nm

 

Stability study:

The stability test was evaluated according to the ICH guidelines on the topic of Q 1 A (R2): stability testing of new drug substances and products. The liquid filled capsules filled with liquid-SEDDS (F7) were stored in air-tight glass containers and protected from light. These samples were maintained under accelerated conditions (40°C ± 2°C, 75 ± 5% RH) with humidity and temperature control, were taken at 1, 2, 3 and 6 months^[26]. Appearance, self-emulsifying properties, % transmittance, % drug content and % drug release of SEDDS were evaluated.

 

RESULTS AND DISCUSSION:

The self-emulsifying drug delivery system (SEDDS) provides an opportunity for the improvement of the in-vitro performance of poorly water-soluble drugs and thus it serves as an ideal carrier for the delivery of drugs belonging to the Biopharmaceutics Classification System (BCS) classes II and IV. The current study was performed to define the role of self-emulsifying formulations to enhance the solubility and bioavailability of the anthelmintic drug, Praziquantel.

 

Solubility study:

The solubility of a drug in excipients plays an important role in determining the stability of the formulation, as many formulations undergo precipitation before undergoing in situ solubilization. Also, for a successful formulation of PZQ loaded SEDDS, the entire dose of PZQ should be soluble in SEDDS ingredients. The solubility of PZQ in various oils, surfactants and co-surfactants are presented in Table no. 1 & 2.

 

Table 1: Solubility of PZQ in various oils

Data expressed as mean ± SD (n = 3)

 

Table 2: Solubility of PZQ in various surfactants & co-surfactants

Data expressed as mean ± SD (n = 3)

Among various vehicles screened, Capmul MCM was selected as the oil phase showing the highest solubilization capacity (57.94 ± 0.70 mg/ml). Cremophore RH40 (95.09 ± 0.75 mg/ml) was used as surfactant & PEG 400 (70.49 ± 0.84 mg/ml) was chosen as co-surfactant.

 

Table 3: Emulsification ability of selected surfactants and co-surfactants by using Capmul MCM as an oily phase

Data expressed as mean ± SD (n = 3)

 

Preliminary screening of surfactants for their emulsification ability::

It has been reported that well-formulated SEDDS is dispersed within seconds under gentle stirring conditions. The results showed that (Table no. 3) the highest % transmittance, i.e. highest emulsification efficiency, is acquired by the following order Cremophore RH 40 > Tween 80 > Tween 20 > Span 20. The Cremophore RH 40 possessed the highest transmittance value and Span 20 as the lowest value.

 

Preliminary screening of co-surfactants:

In the present study, three co-surfactants, namely PEG 400, transcutol and propylene glycol and were compared. Capmul MCM as an oil and Cremophor RH40 used as surfactant showed good % transmittance with all of the cosurfactants (Table no. 3) by following order, transmittance 99.60% with PEG 400 > Transcutol 97.16% > 92.87% with propylene glycol. Based on the results of preliminary screening, Capmul MCM as oily phase, Cremophor RH40 as surfactant and PEG 400 as cosurfactant was selected.

 

Construction of pseudo-ternary phase diagram:

A simple pseudo-ternary phase diagram comprises of oil, water and Smix, where each corner in the phase diagram represents 100% of that particular component. Based on the data obtained from the solubility study and preliminary screening of surfactants & cosurfactant, Campul MCM was used as the oil phase, Cremophore RH40 as surfactant and PEG400 used as co-surfactant for constructing different phase diagrams. The pseudo-ternary phase diagram composed of (Capmul MCM + Cremophor RH40 + PEG 400) in different surfactant/co-surfactant ratio of 1:1, 1:2, 2:1, 3:1 were constructed by using water titration method as shown in figure no. 1 (a), (b), (c) and (d) respectively. The shaded region indicates a micro/nanoemulsion region and the wider region indicates better self-nanoemulsifying ability.

 

Table 4: Characterization parameters of PZQ-SEDDS formulations

Data expressed as mean ± SD (n = 3)

 

Figure 2 (a) XRD spectra of pure drug

 

Figure 2 (b) XRD spectra of optimized formulation (F7)

 

 

Fig. 3: Globule size distribution of F7 formulation

 

X-ray diffraction (XRD) analysis:

XRD studies of Praziquantel pure drug showed several sharp peak at 5-25⁰θ. The SEDDS prepared for Praziquantel optimized formulation (F7) revealed that sharp peak of mixture was observed at 15-25⁰θ. The XRD patterns are shown in figure no. 2 (a) and (b).

 

Determination of self-emulsification time:

The results of self-emulsification time were shown in table no. 4. The lowest self-emulsification time was observed for formulation F7 is 20.33 second.

 

Cloud point measurement:

The cloud point of all the SEDDS formulations were above 63.4^◦C as shown in table no. 4

 

Globule size determination:

The average globule size of F7 formulation was found to be 14.73 nm which was found to be minimum amongst all other formulation as shown in fig. no. 3. The polydispersity index of F7 formulation was found to be 0.117.

 

Zeta potential determination:

The zeta potential of all SEDDS formulations with values ranging from −22.13. to −62.83 mV, indicating a stable system and well-separated emulsion globules.

 

Drug content:

The content of the drug in selected SEDDS formulations was reported in the range of 95.05-99.64%.

 

In-vitro dissolution studies:

In-vitro dissolution studies were performed in 0.1 N HCl using USP type-II dissolution apparatus, to compare the release of drug from different SEDDS formulations (F₁-F₈). SEDDS formulation was subjected to dissolution study and their profiles are presented in Figure no. 4 and 5. F7 optimized formulation showed a maximum drug release of 98.65 % after 30 min. Thus, it can be concluded that the formulated SEDDS improved the solubilization and release rate of PZQ.

 

Fig. 4 In-vitro drug release profile of formulations F1 to F4

 

Fig. 5 In-vitro drug release profile of formulations F5 to F8

 

Table 5: Stability study data of F7 formulation of liquid SEDDS (at 40˚C ± 2˚C/ 75%RH ± 5%RH)

 

Stability study of F7 liquid SEDDS formulation:

The effect of stability condition on storage for 6 months on F7 formulation was studied. The percent transmittance, drug content and drug release were not reduced considerably. From a stability study, it can be concluded that the F7 formulation retained its stability and it was found to be stable during the sixth-month stability study.

 

CONCLUSION:

In this study, self-emulsifying drug delivery system of Praziquantel was prepared and evaluated for paediatric patients. The excipients were selected based on the saturation solubility performance. After performing optimization study, oil (Capmul MCM C8), surfactant (Cremophor RH 40) and co-surfactant (PEG 400) which showed the highest solubility was evaluated further for emulsification ability. The preliminary screening data of selected surfactant and co-surfactant showed more than 99% transmittance with water. The prepared all SEDDS formulations showed cloud point above 63.4°C. The globule size of all formulations was found to be in the nanometric range from 14.73 to 212.8 nm and the zeta potential ranged from -22.13 to -62.83 mV indicating good stability. In-vitro drug release profile of F7 in 0.1N HCL depicted a gradual release pattern with 98.65 % release after 30 minutes. The optimized F7 SEDDS formulation of Praziquantel showed a significant increase in drug release rate.

 

ACKNOWLEDGEMENT:

The authors sincerely acknowledge Microlab Pvt. Ltd. Goa for providing gift sample of Praziquantel.

 

CONFLICT OF INTRESTS:

None declared by the authors.

 

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Accepted on 01.12.2020           © RJPT All right reserved

Research J. Pharm. and Tech 2021; 14(11):5831-5837.