Formulation and Evaluation of Nano structured lipid carriers for intranasal delivery of Buspirone hydrochloride

 

Dyandevi Mathure¹*, Jyotsana R. Madan¹, Hemantkumar Arvind Ranpise², Rajendra Awasthi³, Kamal Dua⁴, Kishor Namdev Gujar²

 

ABSTRACT:

The aim of this work was to formulate buspirone hydrochloride (BH) NLCs for intranasal administration to improve BH bioavailability. The BH loaded NLCs were prepared by hot high-pressure homogenization technique using Precirol ATO 5, olive oil and tween 80 as solid lipid, liquid lipid and surfactant, respectively. Carbopol 934P and HPMC K4M were used to convert NLCs dispersion into NLCs based in-situ nasal gelling solution to improve its mucoadhesive property for intranasal administration. A factorial design approach was used to study the effect of independent variable (amount of Precirol ATO 5 and olive oil) on the dependent variables (particle size and percentage entrapment efficiency (%EE). The optimized formulation was characterized for particle size, zeta potential, %EE, and surface morphology. Fourier transform infrared (FTIR) spectroscopy was used to study the possible BH-lipid complex formation. Further, viscosity determination, stability studies, in- vitro drug release, ex-vivo skin permeation studies and ex-vivo nasal toxicity studies of BH loaded NLCs nasal gelling solution were carried out. The BH loaded NLCs (batch F8) showed particle size of 111.8nm, %EE of 78.34% and zeta potential of -44.3mV. Scanning electron microscopy (SEM) confirmed spherical shape of NLCs. In vitro drug release and ex vivo skin permeation studies of BH loaded NLCs and BH loaded NLCs in-situ nasal gelling solution showed 71.26% drug permeation.

 

 

 

INTRODUCTION:

In present years there has been an increase in research work pertaining to CNS drug delivery. In case of drugs giving unwanted side effects orally, nasal route is significantly effective to achieve faster and higher level of drug absorption¹. Intranasal administration of drugs opens a new possibility of noninvasive delivery due to high blood flow, large surface area; avoidance of first pass metabolism, ready accessibility which leads to improvement in bioavailability^2-6.

 

Many CNS drugs with systemic action, earlier marketed in oral dosage forms have recently been marketed in nasal delivery systems. The reason for the switch from oral to nasal is due to the potentially rapid and high systemic availability of nasally administered drugs⁷. Though many lipophilic drugs have already been explored for delivery through the nasal route, however, researchers have also started exploring the possibilities for CNS delivery of hydrophilic drugs via the nasal route to treat chronic CNS diseases viz; Alzheimer’s disease, Parkinson’s disease or anxiety⁸.

 

The key challenge to the formulator is to overcome the protective barriers of the nasal cavity. It has been reported that brain and cerebro-spinal fluid (CSF) is connected by means of olfactory neuron with the open air that is being inhaled through the nasal cavity. As a result, drugs may have direct access to the CNS following intranasal administration, thereby bypassing the blood brain barrier⁹.

 

Nanostructured lipid carriers (NLCs) are colloidal carrier composed of both solid lipid and liquid lipid. NLCs are superior to conventional lipid-based formulation and Solid lipid nanoparticles (SLNs) in respect to high drug loading, smaller particle size, no particle growth, stability in tropical climates and no drug leakage during storage by lipid polymorphism^10-14. Encapsulation of hydrophilic drugs in lipid-based delivery systems remains a challenge. Due to their hydrophilic nature, most hydrophilic drugs are poorly encapsulated into a hydrophobic matrix and tend to rapid partitioning to the external aqueous phase during the preparation process, thus leading to low encapsulation efficiency. NLCs have higher drug loading capacity due to the imperfect crystal structure and it avoids drug expulsion by avoiding lipid crystallization during the manufacturing and storage periods. NLCs also can increase drug solubility in lipid matrix and they can show more controllable release profiles. As BH is having low lipophilicity, NLCs can be a superior carrier to enhance its lipophilicity for good encapsulation efficiency and drug loading capacity^15-16.

 

The major problem persists with nasal solution is that it is cleared off quickly from the nasal cavity. This problem can be overcome by the use of mucoadhesive gel formulation to decrease the mucocilliary clearance and prolong the residence time at the nasal site of absorption¹⁷.

 

Thus, in the present study, we selected buspirone hydrochloride (BH) an anxiolytic agent. BH exhibits the problems of low oral bioavailability (4%) due to extensive first pass metabolism. The usual dose is 15-30 mg daily and has to be taken in three divided doses owing to its short half-life. Intranasal administration can avoid first pass effect and target the brain for treating anxiety. Thus, NLCs in the form of in-situ nasal gels were prepared to increase the permeability of BH to reach the brain and maintain the desired therapeutic effect^18-20.

 

MATERIAL AND METHODS:

Materials:

Buspirone Hydrochloride (BH) was purchased from Avanscure Pvt. Ltd., Mumbai, India, Precirol ATO 5 and Compritol ATO 888, were gifted by Gattefosse India Pvt. Ltd., Mumbai, India. Olive oil, Tween 80 was purchased from Research Lab Fine Chem Industries, Mumbai, India. HPMC K4M and Carbopol 934P were obtained as a gift sample from Colorcon, Mumbai, India. Sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium chloride along with other chemicals was obtained from Loba Chemie Pvt Ltd., Mumbai, India.

 

Methods:

Preliminary screening of solid lipid:

The Solubility of BH was determined in various lipids viz; Precirol ATO 5, Glyceryl monostearate (GMS), Compritol 888 ATO, cetyl palmitate and stearic acid. Briefly, 10 mg of BH was taken in a clean transparent vial. Lipid was added slowly to the drug. The mixture was stirred at a temperature above 5°C of lipid’s melting point to avoid its crystallization. Formation of a clear transparent lipid drug mixture was taken as the endpoint of the study. Quantity of lipid for complete solubilization of the drug was calculated²¹.

 

Preliminary screening of Liquid lipids and Surfactant:

The solubility of BH in various liquid lipids viz, olive oil, oleic acid, linseed oil, soyabean oil and surfactants viz; Span 20, Tween 20, Tween 40, Poloxamer 188 and Tween 80 was determined by adding excess amount of BH in 5 ml of each of the lipids or surfactant in glass vials. The vials were stirred at 50 rpm using a magnetic stirrer (REMI Instruments Division, Mumbai India) and kept at 37±1.0°C for 24 h to achieve equilibrium. These vials were centrifuged (RM-12CREMI Mumbai, India) at 1000-2000 rpm for 30 min. The samples were filtered through 0.45 μm membrane filter using vacuum filtration and BH was determined by diluting the clear supernatant with methanol and analyzed spectrophotometrically (Jasco V-730, Japan) at 238 nm²².

 

Preliminary trials for preparation of BH Loaded Nanostructured Lipid Carrier (NLC) dispersion:

BH loaded NLCs dispersions were prepared using hot high-pressure homogenization technique using various ratios of solid lipid: liquid lipids and three different concentrations of Tween 80 (Table 1). BH was dispersed in melted lipid phase (Precirol ATO 5 and Olive oil). The aqueous phase (distilled water with tween 80) was heated at 80°C and BH loaded hot lipid phase was emulsified in aqueous phase at the same temperature by high speed stirring using TH homogenizer (Omi TH homogenizer, Omni, USA) at 35,000 rpm for 10 min. This pre-emulsion was then subjected to ultrasonication (Probe sonicator, PCI analytics, Mumbai, India) for 20 min. The obtained o/w emulsion was allowed to cool to room temperature forming NLC dispersion²³.

 

Experimental design:

A 3² factorial design was applied for the determination of effect of independent variables. The amount of Precirol ATO 5: Olive oil (X₁) and concentration of Tween 80 (X₂) were selected as independent variables.

Table 1: Preliminary trials for the preparation of NLCs by hot high-pressure homogenization method.

Formulation code	BH (mg)	Precirol ATO 5: Olive oil	Tween 80 (%)	Water (ml)	Particle size (nm)	EE (%)
F1	10	70:25	0.5	30	120	68
F2	10	70:30	1.5	30	111.8	78.34
F3	10	80:15	1	30	138.4	64.5
F4	10	80:20	1.5	30	121	66.5
F5	10	90:10	2	30	97.7	54.3

 

Table 2: Results of Particle size and Entrapment efficiency of BH loaded NLCs dispersion optimized by 3² factorial design.

Batch Code	Coded Values		Actual Values		Result
	X1	X2	X1 (Precirol ATO 5: Olive oil (% w/w)	X2 (Tween 80) (% w/v)	Particle Size (nm)	Entrapment Efficiency (%)
F1	-1	-1	90:10	1	116	60.58
F2	-1	0	90:10	1.5	110	58.7
F3	-1	+1	90:10	2	97.7	54.3
F4	0	-1	85:15	1	138.4	64.5
F5	0	0	85:15	1.5	122	63.2
F6	0	+1	85:15	2	118.9	59.2
F7	+1	-1	70:30	1	126.7	74.6
F8	+1	0	70:30	1.5	111.8	78.34
F9	+1	+1	70:30	2	110.8	72.31

Coded levels: X₁: Precirol ATO (%): Olive oil (+1): 70:30, (0):85:15, (-1): 90:10

X₂: Tween 80 (%): (+1): 1, (0):1.5, (-1): 2

 

Particle size (nm) (Y₁) and % entrapment efficiency (% EE) (Y₂) were selected as dependent variables. Various models, such as linear, 2FI (Two factor interaction) cubic and quadratic were fitted to the data for two responses simultaneously using Design Expert Software (11.1.2.0, Stat-Ease Inc., USA). The experimental design with corresponding formulations is presented in Table 2.

 

Characterization of NLCs dispersion:

Particle Size and Zeta potential determination:

Particle size and zeta potential were measured using Malvern Zetasizer Nano ZS 90 at 25°C. For the particle size determination, BH loaded NLCs dispersion was appropriately diluted with double-distilled water, followed by filtration through Whattman filter paper before measurement. Depending upon particles electrophoretic mobility, zeta potential was determined²⁴.

 

Entrapment Efficiency:

The percent entrapment efficiency of BH loaded NLCs dispersion was determined by centrifugation method. About 5 ml of NLCs dispersion was taken in a centrifuge tube and centrifuged (REMI- C24 BL, Remi Elektrotechnik Ltd., Vasai, India) at 15000 rpm for 45 min. After centrifugation, the supernatant was removed and diluted with methanol. The concentration of free drug in the supernatant was determined by UV- spectroscopy (UV 1800, Shimadzu, Japan). Entrapment efficiency (% EE) was calculated using the following equation²⁵.

 

 

 

 

Fourier-transform infrared spectroscopy (FTIR):

The BH loaded NLCs dispersion (batch F8) was lyophilized (Labconco, Free Zone 2.5 plus, Missouri, USA) and used for FTIR examination. The FTIR spectrum of pure BH, physical mixture of BH with Precirol ATO5 (1:1) (PM) and lyophilized NLCs (batch F8) were recorded over a range of 4000-400 cm^-1 to distinguish atomic structures and components using FTIR spectrophotometer (IR Prestige-21, Shimadzu Corp., Tokyo, Japan) by potassium bromide disc method^26,27.

 

Differential scanning Calorimetry:

Thermal characteristics of pure BH, PM and lyophilized NLCs (batch F8) were evaluated using differential scanning calorimetry (DSC 4000, Perkin Elmer, Massachusetts, United States). The samples were placed in aluminum pans. An empty aluminum pan was used as a reference. The DSC measurements were carried out at a heating rate of 10°C/min from 30°C to 300°C under nitrogen atmosphere (20 ml/min)²⁸.

 

Morphological characterization:

The morphology of BH loaded NLCs dispersion (batch F8) was determined by using scanning electron microscopy. (JEOL JSM-6360A, Japan).

 

In-vitro drug release:

The In-vitro study was carried out using Type II dissolution apparatus. A dialysis bag (2 x 2 cm, molecular weight cut off: 1200 - 14,000 Dalton; HiMedia Laboratories Pvt. Ltd., Mumbai, India) containing BH loaded NLCs dispersion equivalent to 5 mg of BH to be tested was attached to the paddle. The bag was immersed in 900 ml pH 7.4 phosphate buffer in dissolution apparatus. Temperature conditions were maintained at 37±0.5°C. The samples were withdrawn at predetermined time interval and each sample was replaced with fresh medium to maintain sink condition. The percent drug release at different time interval was analyzed spectrophotometrically at 238 nm²⁹.

 

Preparation of BH NLCs loaded in-situ nasal gelling solution:

For the preparation of BH NLCs loaded in-situ nasal gelling solution, Carbopol 934P (0.2%) was dispersed in water and HPMC K4M (0.6%) was added slowly. The prepared NLCs dispersion (F8 batch) (10 ml) and benzalkonium chloride (1%) were further added to the polymer mixture. Final volume was made up to 30 ml with distilled water. The pH of formulation was adjusted by 0.5M sodium hydroxide solution. The final concentration of BH in the gelling solution was 0.1%w/v. A similar procedure was followed for the preparation of the pure BH gelling solution (0.1% w/v).

 

Characterization of BH NLCs loaded in-situ nasal gelling solution:

BH NLCs loaded in-situ nasal gelling solution showed the gelling time of 4.6±0.32 sec and more than satisfactory gelling capacity. High viscosity was obtained at nasal pH, (2567±0.53 at pH 5 and 7762±0.25 at pH 6) using 0.2% carbopol 934P and 0.6% HPMC K4M.

 

Ex-vivo Permeation Study:

The sheep nasal mucosal membrane was used for permeation study. The study was performed using Franz diffusion cell (Orchid Scientifics, Nashik, Maharashtra, India). In-situ nasal gelling solution and a pure BH loaded gelling solution (0.1% w/v BH in Carbopol 934 P) were studied for permeation. The solutions were positioned in the donor compartment which was in contact with the mucosal surface of the membrane, whereas the receptor compartment was filled with 15 ml of phosphate buffer (pH 7.4). The temperature was maintained at 37°C. Sample (1 ml) was withdrawn at different time intervals and sink conditions were maintained by replacing equal volume of fresh medium. Percent BH permeation was determined using a UV spectrophotometer at 238 nm.

 

Ex-vivo sheep nasal toxicity study:

Ex-vivo nasal toxicity studies were performed using freshly isolated sheep nasal mucosa obtained from the slaughterhouse. After cleaning with saline solution, sections of the mucosa were treated with BH NLCs dispersion and BH NLC loaded in-situ nasal gelling solution (BH-INF). Untreated mucosa was used as the control. After a period of 8 h, all the samples were washed with distilled water and stained using hematoxylin and eosin. All the sections were examined to detect damage to the mucosa if any, on an optical microscope^30,31.

 

Accelerated stability studies:

Stability studies of BH NLCs loaded in-situ nasal gelling solution (BH-INF) were carried out as per ICH Q1A guidelines. BH-INF were kept in screw cap bottles and kept in stability chamber for a period of 6 months at 25±5°C/60±5% RH, 40±5°C/75±5% RH. The samples were analyzed periodically for physical appearance and ex-vivo permeation for 6 months. The sampling intervals were 0, 2, 3 and 6 months (s).

 

RESULTS AND DISCUSSION:

Preliminary screening of Solid lipids, Liquid lipids and surfactant:

The solubility of BH was determined in various solid lipids and liquid lipids. BH had maximum solubility of 20 mg/mg and 25.71 mg/mg in Precirol ATO 5 and olive oil, respectively (Table 3). Thus, solid lipids and liquid lipid in which drug had highest solubility were selected for fabrication of NLCs.

 

Table 3: Solubility study results of BH in different solid lipids, liquid lipids, and surfactants.

Components	Solubility
Solubility of BH in different solid lipids (mg/mg (amount mg required to dissolve 10 mg of BH)
Compritol 888 ATO	300 ± 0.53
Cetyl Palmitate	500 ± 0.35
Stearic Acid	600 ± 0.86
Precirol ATO 5	20 ± 0.63
Glyceryl Monostearate	80 ± 0.28
Solubility of BH in different liquid lipids (solubility mg/ml)
Olive oil	25.71± 0.25
Oleic acid	18.98±0.43
Linseed oil	12.65±0.28
Soyabean oil	7.87±0.39
Solubility of BH in different surfactants (solubility mg/ml)
Span 20	13.8±0.21
Tween 20	16.5± 0.46
Tween 40	19.1±0.53
Tween 80	31.3 ± 0.23
Poloxamer 188	26.8 ± 0.62

 

Screening of surfactants:

Surfactant plays a major role in stabilization of colloidal particles. It was observed that BH presented highest solubility in Tween 80 (Table 3). Thus, Tween 80 was selected as a surfactant for further formulation development.

 

Preliminary trials for preparation of BH Loaded Nanostructured Lipid Carrier (NLCs) dispersion:

During preliminary trials, it was observed that the particle size was reduced as the concentration of Liquid lipid increases. Tween 80 was used as surfactant during these trials to prepare NLCs (Table 1). The lowest particle size of NLCs was obtained for batch F2. It has been reported that use of surfactants prevents particle aggregation, improves physical stability, and promotes particle properties of NLCs³². Based on the results of preliminary trials, further experiments were carried out.

 

Experimental design:

The two independent variables selected were solid lipid: liquid lipid (Precirol ATO 5: Olive oil) and Tween 80 concentration and the dependent variable were particle size (PS), entrapment efficiency (%EE). Nine experiments were designed and each variable was tested at 3 designated levels - 1, 0 and +1 (Table 2). The mean particle size and %EE (dependent variable) of BH loaded NLCs dispersion obtained at various levels of 2 independent variables (X₁ and X₂) were subjected to multiple regression analysis to yield full model second order polynomial equation. Response surface plots were plotted to identify the impact of significant variables utilizing Design-Expert^® Software 11.1.2.0. Model summary statistics, fit summary and ANOVA were applied to determine the significance and magnitude of interaction between independent and dependent variables. The regression model was used to generate the contour plots and 3D surface plots to analyze interactions of the independent variables^33,34. The results of the regression output and response of model summary statistics of BH loaded NLCs dispersions are presented in Table 4. The corresponding equations for the model summary statistics are:

 

Y₁ (PS) = 124.11+4.26X₁-8.95X₂+0.60X₁X₂-14.27X₁²+3.48X₂²

Y₂ (% EE) = 63.16+8.61 X₁-2.31 X₂+1 X₁ X₂+4.17 X₁²-2.50 X₂²

 

Where, X₁ and X₂ represent the coded values of the Precirol ATO 5: Olive oil (X₁) and Tween 80 (X₂), respectively.

 

Statistical analysis:

The information is expressed as the mean ± standard deviation. The statistical analysis was finished utilizing Design master software 11.1.2.0. ANOVA repeated measures analysis of variance was used to assess the significance of the difference between quantitative variables. P < 0.05 was statistically significant. The focus was on model maximizing the adjusted r² and the predicted r².

 

The particle size values showed a wide variation ranging from 97.7 to 138.4 nm, while % EE values varied from 54.3% to 78.34%. A significantly high % EE was achieved in BH loaded NLCs dispersion (78.34%) at X₁ (70:30) and X₂ (1.5%) in batch F8 and this batch showed particle size of 111.8 nm.

 

Response surface plots:

The response surface plot (Figure 1A) signifies the effect of the amount of Precirol ATO 5: olive oil (X₁) and the tween 80 (X₂) on the response Y₂ (% EE). Amongst the various solid lipid: lipid liquid ratios, 70:30 ratio gave the highest entrapment efficiency as was observed in batches (F7-F9). On increasing Tween 80 from 1% to 1.5% the entrapment efficiency increases, however on further increase in Tween 80 there is no further increase in %EE.

 

The response surface plot (Figure 1B) signifies the effect of the amount of Precirol ATO 5: Olive oil (X₁) and Tween 80 (X₂) on the response Y₁ (particle size) A low concentration of Precirol ATO 5 along with a high concentration of olive oil (70:30) led to a decrease in particle size. The F8 batch exhibits particle size of 111.8 nm which clearly indicates that on increasing liquid lipid concentration and decreasing solid lipid concentration the particle size decreases.

 

 

Table 4: Results of ANOVA for particle size as response Y1 and % EE as response Y2.

Source	Sum of square	DF	Mean Square	F Value	p-value probe>F	Remarks
Particle size as response Y1
Model	1022.62	5	204.52	13.35	0.00291	Significant
A*	109.23	1	109.23	7.13	0.0757	Significant
B*	480.61	1	480.61	31.38	0.0112	Significant
AB	1.44	1	1.44	0.094	0.7792	Significant
A2	407.08	1	407.08	26.58	0.0142	Significant
B2	24.27	1	24.27	1.58	0.2972	Significant
% EE as response Y2
Model	528.30	5	105.66	52.46	0.0040	Significant
A*	444.96	1	444.96	220.93	0.0007	Significant
B*	32.06	1	32.06	15.92	0.0282	Significant
AB	3.98	1	3.98	1.98	0.2545	Significant
A2	34.81	1	34.81	17.28	0.0253	Significant
B2	12.48	1	12.48	6.20	0.0885	Significant

 

 

Figure 1: Response surface plots for (A) percentage entrapment efficiency and (B) particle size.

 

Characterization NLCs dispersion:

Particle Size:

The amount of lipid had a great effect on particle size, since a small increase in amount of lipid decreased particle size significantly. Based on the factorial design studies, batch F8 with particle size 111.8 nm (Figure 2A) was selected for further loading into in-situ nasal gelling solution.

 

 

Figure 2: Particle size (A) and zeta potential (B) of buspirone hydrochloride loaded nano structured lipid carrier’s dispersion (Batch F8).

 

Zeta potential:

The estimation of zeta potential predicts the stability of colloidal dispersions. BH loaded NLCs dispersion (batch F8) which shows the highest entrapment efficiency (78.34 %) and lowest particle size (111.8 nm) has a zeta potential of -44.3 mV (Figure 2B). This indicates a strong electrostatic repulsion, rendering the formulation stable.

 

Fourier-transform infrared spectroscopy (FTIR):

The FTIR spectra of pure BH, PM, and lyophilized NLCs (batch F8) are presented in Figure 3A. The FTIR spectrum of pure BH revealed the characteristic absorption bands at 2952.31cm^-1 (C-H stretching), 1674 cm^-1 (C=O stretching), 1480.41 cm^-1 (C=C stretching), 1273.36 cm^-1 (C-N stretching). The existence of all the characteristic peaks of BH in PM and lyophilized NLCs confirms the presence of BH in NLCs dispersion (batch F8), indicating no chemical interaction between the drug and lipid matrix. However, the intensity of the characteristic peaks of BH was decreased in the spectrum of lyophilized NLCs which might be attributed to change in molecular environment and intermolecular interactions associated with dispersed drug molecule in lipid components.

 

Figure 3: FTIR spectrum (A) and DSC thermogram (B) of buspirone hydrochloride, physical mixture and lyophilized nano structured lipid carriers (Batch F8).

Differential Scanning Calorimetry:

DSC thermogram gives the information about crystalline or amorphous nature of the drug. In the thermogram of pure BH, two endothermic peaks at 190.49°C and 204.72°C were recorded corresponding to its melting point, confirmed crystalline nature of BH (Figure 3B). The thermogram of physical mixture showed two discrete endothermic peaks, the first endothermic peak at 58.62°C and the second endothermic peak at 192.49°C (Figure 3B). A slight shift in the BH peak was recorded in the thermogram of PM which may be due to the interaction of the BH with the lipid matrix. The DSC thermogram presented in (Figure 3B) reveals the disappearance of BH peak in the BH NLCs loaded in-situ nasal gelling solution which suggested that the drug is completely enclosed within the lyophilized NLCs.

 

Morphological Characterization:

Figure 4A shows the SEM image of NLCs dispersion (batch F8) indicating spherical shape and nano size of the particles.

 

In-vitro drug release:

Figure 4B shows the percent cumulative release of NLCs dispersion batches F1-F9. The cumulative percent release of NLCs dispersion ranges from 53.21±0.32 to 71.26±0.52%.

 

Figure 4: Scanning electron micrograph (Batch F8) (A), percentage drug release profile of buspirone hydrochloride from synthesized nano structured lipid carriers’ dispersions (batches F1-F9) (B), and Ex-vivo permeation for nano structured lipid carriers loaded in-situ nasal gelling solution and plain gel (C).

 

Preparation of BH NLCs loaded in-situ nasal gel:

The BH NLCs loaded in-situ nasal gelling solution was prepared by using carbopol 934P (0.2%) and HPMC K4M (0.6%). Low concentration of polymeric components is used to obtain lowered buffering capacity and thermal gelation threshold. The use of carbopol in in-situ gelling system is substantiated by the property of its aqueous solution to transform into stiff gels when pH is raised^35,36. The rheological properties of gel may be improved by the addition of viscosity enhancing polymer such as HPMC K4M. Gel prepared using a combination of these polymers resulted in clear, transparent gel with good rheological properties.

 

Characterization of BH NLCs loaded in-situ nasal gel

Ex-vivo permeation studies:

Ex-vivo permeation study of BH NLCs loaded in-situ nasal gelling solution was performed using sheep nasal mucosa. The result of permeation study was shown in Figure 4C. BH NLCs loaded in-situ nasal gelling solution showed permeation of BH (71.26%) through the sheep nasal mucosa in 8 h. Plain BH loaded gel is a Carbopol 934P based gel representing a simple, aqueous system with buspirone hydrochloride dispersed in the matrix. Permeation studies of BH from plain BH loaded gel determines the permeation properties of the drug. From Figure 4C, it was observed that plain BH loaded gel gives 60% permeation through sheep nasal mucosa in 8h, as compared to NLCs loaded in situ nasal gelling solution which shows 71.26 % BH permeation.

 

Ex-vivo nasal toxicity study:

These studies were performed to determine the toxicity of the components of the formulation onto the nasal mucosa, if any. The untreated nasal mucosa i.e. controls (Figure 5A) showed intact basement membrane with epithelial layer. Nasal tissue treated with BH NLCs dispersion and BH INF (Figure 5 B and C) showed no signs of toxicity to epithelial layer, indicating the safety of the selected excipients used in NLCs dispersion and safety of developed NLCs in-situ gelling solution. Thus, NLCs based in situ nasal gelling solution (BH-INF) is safe for administration through the nasal route.

 

Accelerated stability studies:

The BH NLCs loaded in-situ nasal gelling solution was subjected to ex-vivo permeation study to determine the percentage drug permeated in 8 h. The results showed that formulation had comparable ex-vivo permeation (Table 5), thus suggesting that BH NLCs loaded in-situ nasal gelling solution of BH were stable.

 

Figure 5: Ex-vivo nasal toxicity study for (A) untreated mucosa (control), (B) mucosa treated with buspirone hydrochloride loaded nano structured lipid carrier’s dispersion, and (C) mucosa treated with buspirone hydrochloride loaded in-situ nasal gelling solution

 

 

Table 5: Stability study of BH NLCs loaded in-situ nasal gelling solution

Parameters	Testing points
	0 day	1st month	2nd month	3rd month	6th month
Ex-vivo permeation (%)	71.26±0.22	70.63±0.63	71.89±0.52	72.00±0.28	71.98±0.26
Physical appearance	Homogeneous Clear solution with no sedimentation	Homogeneous Clear solution with no sedimentation	Homogeneous Clear solution with no sedimentation	Homogeneous Clear solution with no sedimentation	Homogeneous Clear solution with no sedimentation

 

CONCLUSION:

In the current study hot high-pressure homogenization method was used to prepare BH loaded nanostructured lipid carriers of optimum particle size of 111.8 nm. BH loaded NLCs dispersion (Batch F8) showed better physical stability and a high entrapment efficiency. Further, the prepared BH NLCs were loaded in in-situ nasal gelling solution which showed the desired properties of clarity, appearance, consistence and gelling capacity at nasal pH. Ex-vivo drug permeation studies indicate that the effect of drug was prolonged by prepared optimized NLCs loaded in-situ nasal gelling solution. The Ex-vivo nasal toxicity studies show no sign of toxicity. Thus, BH NLCs loaded gelling solution proved the potential for intranasal drug delivery of BH over the conventional gelling solution formulation.

 

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

 

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Received on 02.03.2020            Modified on 14.06.2020

Accepted on 10.08.2020         © RJPT All right reserved