Design and Characterization of Solid Lipid Nanoparticle Based Transdermal Drug Delivery System

 

Prashant S. Wake^1*, Dr. M. D. Kshirsagar²

¹Research Scholar, P. Wadhwani College of Pharmacy, Yavatmal (M. S.)

²Professor, P. Wadhwani College of Pharmacy, Yavatmal (M. S.)

 

ABSTRACT:

Transdermal drug delivery system (TDDS) is the dosage forms which deliver a therapeutically effective amount of drug across a patient’s skin. The Solid lipid nanoparticles were successfully developed for rasagiline mesylate. SLN dispersions were prepared by melt emulsification and solidification at low temperature method. Physicochemical characterization including particle size, particle size distribution, Zeta potential, scanning electron microscopy, crystallinity study by DSC were carried out. In the Transdermal Drug Delivery System, Formulations F1-F9 was prepared by solvent casting method using 1.5%, 2.5% and 3.5% of HPMC K4M and 20%, 30% and 40% (w/w of dry polymer) of PEG 400. The formulation F5 was selected as the promising formulation on the basis of tensile strength, % elongation, and % drug content. Further, the patch was found to be free of skin irritation. From the results stability study it can be concluded that the patches can be stored at 40°C and 75% RH without any significant stability problems. The formulation satisfied all the pharmaceutical parameters of transdermal films and appears to be promising.

 

 

 

1. INTRODUCTION:

Transdermal drug delivery system (TDDS) is the dosage forms which deliver a therapeutically effective amount of drug across a patient’s skin. It increases patient compliance and avoid first pass metabolism over injectables and oral routes. Solid lipid nanoparticles are at the forefront of the rapidly developing field of nanotechnology with several potential applications in drug delivery, clinical medicine and research as well as in other varied sciences.

 

 

SLN as colloidal drug carrier combines the advantage of polymeric nanoparticles, fat emulsions and liposome; due to various advantages, including feasibility of incorporation of lipophilic and hydrophilic drugs, improved physical stability, low cost, ease of scale-up, and manufacturing. SLNs are prepared by various advanced techniques. The site specific and sustained release effect of drug can better achieved by using SLNs. Nanoparticles have been used extensively for applications in drug discovery, drug delivery, and diagnostics and for many others in medical field.^1-2

 

Present Study was done to prepare the optimize formulation of SLN Loaded Transdermal Drug Delivery System containing Rasagiline Methysylate. Rasagiline is used to treat symptoms of Parkinson's disease both alone and in combination with other drugs. It has shown efficacy in both early and advanced Parkinsons, and appears to be especially useful in dealing with non-motor symptoms like fatigue³.

 

2. MATERIAL AND METHOD:-

Rasagiline Mesylate was supplied as gift sample by Anazeal Research Pvt. Ltd., Mumbai, India. Stearic acid, tween 80, Methanol, Acetone, HPMC K4M, Propylene Glycol 400, DMSO and IPA were procured from from S.D. fine-chem Ltd. All other ingredients were of analytical reagent grade.

 

3. EXPERIMENTAL DETAILS:

3.1 Methodology of the Experiment⁴:

SLNs loaded with Rasagiline Mesylate were prepared using melt emulsification and low-temperature Solidification method. Rasagiline Mesylate was dissolved in methanol and mixed with acetone solution containing stearic acid. The mixtures were sonicated for 15 minute, and then added drop wise to Tween 80 solution, stirred at 3000 rpm for 0.5 h at 70 °C temperature. The mixed solution was transferred to icy water bath and stirring for four hour at 3000 rpm. Different formulations of drug loaded SLN were prepared by varying concentrations of stearic acid as shown in the below Table 1.

Table 1 Composition of solid lipid nanoparticles formulation containing Rasagiline

Ingredients	F1	F2	F3	F4	F5	F6
Rasagilline Mesylate (mg)	100	100	100	100	100	100
Stearic Acid (mg)	1000	1250	1500	1000	1250	1500
Tween 80 (%)	2.5	2.5	2.5	2.0	2.0	2.0
Methanol (ml)	1	1	1	1	1	1
Acetone (ml)	1	1	1	1	1	1

 

3.2 Formulation of transdermal patch⁵

Transdermal patches were prepared by solvent casting method. In this method polymeric solution of HPMC K4M was prepared by dissolving weighed quantity of HPMC K4M in IPA. Then calculated quantity of PEG 400 was added and mixed well till clear solution was obtained. The resultant solution was allowed to stand till all entrapped air bubbles get removed. Then solution was poured into a clean and dry glass petri dish containing DMSO and allowed to dry. The dried patches were carefully removed from the petri dish, checked for any imperfections or air bubbles and cut in to pieces of 4 cm².

 

 

Table 2 Composition of Transdermal Patches of formulation containing SLN of Rasagiline

 

 

 

4. EVALUATION:

4.1 Evaluation of solid lipid nanoparticles:^6-7

4.1.1 Measurement of particle size:

The average particle size of SLN formulations were measured by Zetasizer DTS (Malvern Instrument, UK). The samples of SLN dispersions were diluted with deionized water. The results of average particle size were obtained from instrumental based calculation system and data reported in Table.

 

4.1.2 Measurement of Zeta Potential:

Zeta potential of SLN formulations were determined by Zetasizer (Malvern Instruments, UK). Samples were appropriately diluted with deionized water to obtain 50 and 200 Kcps for the measurements. Samples were placed in the cubit available for instrument and zeta potential measured directly.

 

 

4.1.3 TEM:

Solid lipid nanoparticles were observed by transmission electron microscopy. Samples of SLN were diluted to ten time and then mounted on gold plate. The mounted plates were dried and examined under a transmission electron microscope (Philips Morgangni 268D, Netherland) without using any kind of stain. The CCD camera and soft image system was employed with the transmission electron microscope to visualize SLN. The photomicrograph of solid lipid nanoparticles is given in Figure 1.

 

4.1.4 Encapsulation efficiency of solid lipid nanoparticles:

Amount of drug encapsulated in solid lipid nanoparticles were calculated as encapsulated efficiency (EE). Solid lipid nanoparticles were kept in dialysis tube (molecular weight cut off 12 KD, HiMedia Laboratories Pvt. Ltd., India) and dialyzed. Thirty milliliter of 30% v/v PEG 400 in phosphate buffer (pH-6) solution was used as dialyzing medium. Dialysis of solid lipid nanoparticles was performed for two hour. The one hundred miligram of dialyzed solid lipid nanoparticles were taken from dialysis bag and analyzed for drug content by high performance liquid chromatography (HPLC), (Shimadzu, Japan). The samples were suitably diluted and filtered through Millipore membrane filter (0.2 μm; Millipore Corporation, USA), an aliquot of 20 μl was injected into HPLC column and assayed for drug content.

 

Amount of testosterone found in solid lipid nanoparticles

EE% =----------------------------------------------------------------------X 100

Amount of testosterone added during preparation of solid lipid nanoparticles

 

 

4.2 Evaluation of Transdermal Drug Delivery Systems^8-10:

4.2.1 Thickness of the patch:

The thickness of the films was determined by measuring the thickness at random sites on the formulated films using micrometer screw gauge and the average thickness was determined.

 

4.2.1 Tensile strength:

The tensile strength of the patches was determined by using a tensile strength instrument. Average reading of three patches was taken as the tensile strength. The transdermal patch was fixed to the assembly, the weights required to break the patch was noted, and simultaneously elongation was measured with the help of a pointer mounted on the assembly and calculated the tensile strength of the patch using the following formula

 

T. S. = break force/ a.b (1+ΔL/L)

 

Where a, b and L are width, thickness and length of the patch respectively.

ΔL is the elongation of patch at break point.

Break force = Weight required to break the patch (Kg)

 

4.2.2 Weight uniformity:

The prepared patches will be dried at 60°c for 4 hrs before testing. A specified area of patch will be cut in different parts of the patch and weigh in digital balance. The average weight and standard deviation values will be calculated from the individual weights.

 

4.2.3 Folding endurance:

Folding endurance of the film was determined by repeatedly folding a small strip of film at the same place till it broke. The number of times, the film could be folded at the same place without breaking, gave the value of folding endurance.

 

 

4.2.4 Percentage moisture content:

The prepared films will be weighed individually and will be kept in a desiccators containing fused calcium chloride at room temperature for 24 hrs. After 24 hrs the films will be reweighed and determine the percentage moisture content from the below mentioned formula.

 

                          Initial weight- Final weight

Percentage =  ---------------------------------------------×100

moisture content             Final weight

 

4.2.5 Percentage moisture uptake:

Films will be weighed and kept in desiccators at room temperature for 24 hrs containing saturated solution of potassium chloride in order to maintain 84% RH. After 24 hrs, the films will be reweighed and the percentage moisture uptake will be determined from the below mentioned formula.

 

                           Final weight- Initial weight

Percentage =  ---------------------------------------------×100

moisture uptake             Initial weight

 

4.2.6 Drug content

The uniformity of drug content of the transdermal film was determined, based on dry weight of drug and polymer used by means of a UV spectrophotometer method. The formulated patch was cut into pieces and dissolved in 10 ml of methanol/ chloroform. The resulting solution was quantitatively transferred to volumetric flasks, and appropriate dilutions were made with phosphate buffer pH 7.4 and filtered through 0.22 μ filter and analyzed for ketoprofen content at 268.81 nm by using UV spectrophotometer.

 

4.2.7 Uniformity of dosage unit test:

An accurately weighed portion of the patch will be  cut into small pieces and transferred to a specific volume volumetric flask, dissolved in a suitable solvent and sonicate for complete extraction of drug from the patch and made up to the mark with same. The resulting solution will be allowed to settle for about an hour, and the supernatant will be suitably diluted to give the desired concentration with suitable solvent. The solution will be filtered using 0.2m membrane filter and analyzed by suitable analytical technique (UV or HPLC) and the drug content per piece will be calculated.

 

4.2.8 Stability studies as per ICH guidelines:

Stability studies will be conducted according to the ICH guidelines by storing the TDDS samples at 40±0.5°c and 75±5% RH for 6 months. The samples will be withdrawn at 0,30,60,90 and180 days and drug content will be analyzed.

 

5. RESULTS AND DISCUSSION:

5.2.1 Characterization of Solid Lipid Nanoparticle:

5.2.1.1 Particle size, Particle size distribution and Zeta potential:

The d₉₀ for F1, F2, F3, F4, F5 and F6 determined using Malvern Mastersizer showed The particle sizes of formulations were increases as the concentration of tween 80 decreases as shown in table 3.The zeta potential of the SLN dispersion is given in the table 3. Zeta potential for F3 and F6 dispersion it was -25.7 and -21.8. The presence of drug causes a diminution of surface charge of all the investigated samples because probably a share of drug is situated on the lipid nanoparticles surface.

 

5.2.1.1 Drug entrapment efficiency:

From the results given in table 3, it has been observed that, the high lipid concentration containing formulation F3 have higher entrapment as compare to other formulations. The F3 dispersion has 71.767% entrapment, while F1 and F2 have 60.585% and 67.367% respectively. Same as seen in F6 as compare to F4 and F5.

 

 

Table 3: Particle size distribution, zeta potential and entrapment efficiency of different formulations of SLN

 

 

5.2.3 TEM

 

Figure 1 Electron photomicrograph SLN formulation

 

5.3 Evaluation of transdermal drug delivery systems

Table 4 Thickness, tensile strength, % Elongation and folding endurance of transdermal patch

*Mean value ±SD (n=3)

 

Table 5 % moisture absorption, %   moisture Loss, Drug Content (%), Surface pH and Weight variation of transdermal patch

*Mean value ±SD (n=3)

5.5 Stability Study:

The promising formulation F5 was subjected at 40 ± 0.5°C temperature and 75 ± 5 % RH for 1 month to check the stability. The results of thickness, drug content, folding endurance and other parameters after 1 month storage of prepared transdermal patches are shown in table 6.

 

Table 6 Comparison between Predicted value and Experimental value of checkpoint formulation

Parameter	At 0 day*	After 30 days*
Thickness	0.17±009	0.17±008
Tensile strength	442.74± 1.316	442± 1.498
% Elongation	38.66 ± 0.37	38.36 ± 0.92
Folding endurance	>300	>300
% Moisture Absorption	5.48 ± 0.789	4.55 ± 0.168
% Moisture loss	6.78 ± 0.136	4.89 ± 0.765
Drug content	99.51 ± 0.819	98.65 ± 1.658
Surface pH	6.15 ± 0.649	5.68 ± 0.168
Weight Uniformity	0.816 ± 0.009	0.781 ± 0.248

 

5. CONCLUSION:

The Solid lipid nanoparticles were successfully developed for rasagiline mesylate. SLN dispersions were prepared by melt emulsification and solidification at low temperature method. Physicochemical characterization including particle size, particle size distribution, Zeta potential, scanning electron microscopy, crystallinity study by DSC were carried out. It was seen that increasing the stearic acid concentration led to higher entrapment and by increasing the concentration of tween 80 lead to smaller the particle size. In the Transdermal Drug Delivery System, Formulations F1-F9 was prepared using 1.5%, 2.5% and 3.5% of HPMC K4M and 20%, 30% and 40% (w/w of dry polymer) of PEG 400. The formulation F5 was selected as the promising formulation on the basis of tensile strength, % elongation, % drug content and mainly cumulative % drug diffusion. Further, the patch was found to be free of skin irritation. From the results stability study it can be concluded that the patches can be stored at 40°C and 75% RH without any significant stability problems. The formulation satisfied all the pharmaceutical parameters of transdermal films and appears to be promising, would be able to offer benefits such as sustained drug release, reducing frequency of administration, improving bioavailability, and thereby may help to improve patient compliance.

 

6. REFERENCES

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4.       American Psychiatric Association: Diagnostic and statistical Manual of Mental Disorders, Fourth Edition. Washington, DC: American Psychiatric Association, 1994.

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6.       Bhandari R., Kaur  P., A Method to Prepare Solid Lipid Nanoparticles with Improved Entrapment  Efficiency of Hydrophilic Drugs. Current Nanoscience, 2013(9) 1573-4137.

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Received on 26.03.2017       Accepted on 15.05.2017     

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