INTRODUCTION:

In biopharmaceutical classification system (BCS), drugs with low aqueous solubility and high membrane permeability are categorized as class–II drugs. One of such drugs which fall under this category is Quetiapine. Now-a-days solid dispersion technique is mostly employed to enhance the dissolution rate of poorly soluble drugs. Solid dispersions are a group of solid products consisting of a hydrophilic matrix and a hydrophobic drug¹. As they increase the dissolution rate of drug at the absorption site, there is a gradual increase in the bioavailability too².

The solid dispersions were prepared using various techniques like physical mixing, solvent evaporation, kneading etc. Polymers like sodium starch glycolate, croscarmellose, polyvinyl pyrrolidine etc provides instantaneous degradation of the formulation³. They are effective even at low concentrations. They are added to the formulation to promote the breakup of slugs into smaller fragments in an aqueous environment thereby increasing the available surface area and promoting a more rapid release of the drug substance. They promote moisture penetration and dispersion⁴. Solid dispersions are investigated in many studies because they are highly versatile in their application⁵. Therefore, solid dispersion technologies are particularly promising for improving the oral absorption and bioavailability of BCS Class II drugs^6,7. Anxiety is an emotional state, unpleasant in nature, associated with uneasiness, discomfort and concern or fear about some defined or undefined future threat. Some degree of anxiety is a part of normal life⁸. Schizophrenia is a mental disorder characterized by abnormal behaviour, strange speech, and a decreased ability to understand reality. Other symptoms are false beliefs, unclear or confused thinking, hearing voices that do not exist, reduced social engagement and emotional expression, and lack of motivation. People with schizophrenia often have additional mental health problems such as anxiety, depression, or substance-use disorders⁹.

Quetiapine which is an atypical antipsychotic agent is selected as drug of choice for the present study. It is used for the treatment of schizophrenia, bipolar disorder and major depressive disorder. Quetiapine acts by many mechanisms. It acts as a dopamine, serotonin and adrenergic antagonist. The major active metabolite of Quetiapine is norquetiapine. The drug is highly bound to plasma proteins (83%). The approximate elimination half-life of 7h is observed for parent compound and 9-12h for active metabolite¹⁰. Being a BCS class – II drug and as anxiety is the major problem that is being faced by many people, Quetiapine is selected as drug of choice for present study. Plasdone being a stable, water soluble polyvinylpyrrolidine is an effective binder in formulation of pharmaceuticals was selected for the current study.

The main aim of the current study was to formulate Quetiapine solid dispersions using plasdone K-29/32 and to evaluate its pharmacodynamic property.

MATERIALS AND METHODS:

Quetiapine and Plasdone K-29/32 were gift samples from M/s. Natco Pharma Ltd. (Hyderabad, India). Concentrated hydrochloric acid and methanol were procured form S.D Fine Chem. Ltd. (Mumbai, India). Atropine was commercially procured from Intas Pharmaceuticals Ltd. (Ahmedabad, India).

Preparation of Quetiapine Solid Dispersions by Physical Mixing Method:

The physical mixtures were prepared by weighing calculated amount of Quetiapine and plasdone K-29/32 and then mixing them in a glass mortar by triturating. The resultant physical mixture was passed through 44-mesh sieve and stored in desiccator for further studies¹¹. The amount of drug was kept constant and the concentration of polymer was increased. Different formulations with various drug to polymer ratios were placed in table 1.

Preparation of Quetiapine Solid Dispersions by Solvent Evaporation Method:

Specified quantity of Quetiapine and plasdone K-29/32 were taken in a china dish and few ml of methanol was added and slightly heated until both drug and polymer dissolves. Then it is subsequently allowed to evaporate. The obtained mixture was dried, passed through the sieve no.80, packed in a wide mouthed amber colored glass container and was hermetically sealed and stored^{12, 13}. Different formulations with various drug to polymer ratios were placed in table 2.

Evaluation of Physical Parameters for Quetiapine Solid Dispersions:

The prepared solid dispersions were evaluated for various physical parameters such as angle of repose, Carr’s index and Hausner's ratio^14,15. The results were given in table 3.

Drug Content Uniformity for Solid dispersions:

Solid dispersions of Quetiapine were taken and transferred into a 100ml volumetric flask and 40ml of methanol was added to it. It was shaken occasionally for about 30 minutes then it was filtered using Whatmann filter paper. From the filtrate 10ml was taken into 100ml volumetric flask and the volume was made up to 100ml by adding 0.1N hydrochloric acid. About 10ml of the solution from the volumetric flask was taken and centrifuged. Then the filtrate was subsequently diluted and the absorbance was measured at 250nm. This test was repeated six times (N=6) for each formulation.

In vitro Dissolution Studies of Quetiapine Solid dispersions:

Dissolution studies for each formulation were performed in a calibrated 8 station dissolution test apparatus (LABINDIA DS8000) equipped with paddles (USP apparatus II method) employing 900ml of 0.1N hydrochloric acid as a dissolution medium¹⁶. The paddles were operated at 50 rpm and temperature was maintained at 37±1ºC throughout the experiment. The samples were withdrawn at 5, 10, 15, 20, 30, 45 and 60 minutes and replaced with equal volume of same dissolution medium to maintain the constant volume throughout the experiment. Samples with drawn at various time intervals were suitably diluted with same dissolution medium and the amount of the drug dissolved was estimated by Lab India double beam U.V spectrophotometer (UV 3000+) at 250nm. The dissolution studies on each formulation were conducted in triplicate. The dissolution profiles for all formulations were shown in figures 1 and 2.

Dissolution parameters such as first order constant and Hixson-crowell constant were calculated from the dissolution data obtained for various formulations and given in table 3.

Characterization Studies:

Based on the dissolution studies, the optimized formulations were selected, and Fourier transfer infrared (FT-IR) studies were performed to observe the drug–polymer interactions. The results were shown in figure 3.

Evaluation of Anti-Anxiety and Anti-Schizophrenic Activities on Wistar Rats:

Experimental Animals:

Healthy adult male albino mice weighing 20–25g were housed in polypropylene cages, maintained under standardized condition i.e., 12:12 hour light/dark cycle at 25±2⁰C with paddy husk bedding at the animal house, Chebrolu Hanumaiah Institute of Pharmaceutical Sciences, Guntur, India and provided with standard pellet food and had free access to purified drinking water. The guidelines of Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), Ministry of Social Justice and Empowerment, Government of India were followed and prior permission was soughted from Institutional Animal Ethics Committee for conducting the study (1529/PO/Re/11/CPCSEA./CHIPS/IAEC7/PRO-09/2019-20).

Induction of Anxiety and Schizophrenia in Albino Mice:

Anxiety and schizophrenia was induced by chronic administration of Atropine (1mg/kg/day) for 14 days. Animals were randomly divided into four groups with five mice each. Group-I which is a vehicle control, received normal saline (p.o). Group-II, Atropine control received only Atropine (1mg/kg/day – i.p) for 14 days. Group-III and IV animals were injected with Atropine daily up to 14 days and respectively treated with 5 mg/kg (p.o) of Quetiapine pure drug and optimized Quetiapine solid dispersion 5mg/kg (p.o) before 15 minutes of testing on 14^th day.

The anti-anxiety and anti-schizophrenic activities of Quetiapine were evaluated by open field test and Morris water maze method respectively.

Evaluation of Anti-Anxiety Effect on Albino Mice by Open Field Test:

A large open field is used for testing of anxiety and exploratory behaviour as well as locomotion. The open field apparatus was constructed of white plywood and measured 90 x 90cm. Black lines were drawn on the floor with a marker. The lines divided the floor into thirty six 15 x 15cm squares. A central square (15 cm x 15cm) was drawn in the middle of the open field¹⁷. The central square is used because some strains have high locomotor activity and cross the lines of the test chamber many times during a test session. Also, the central square has sufficient space surrounding it to give meaning to the central location as being distinct from the outer locations^18,19. The maze was located in a well ventilated and lightened test room. Behaviour was scored manually.

Procedure:

Mice were placed on one of the four corners of the open field and allowed to explore the apparatus for 5 minutes. After 5 minutes, mice were returned into their home cages and the open field was cleaned with 70% ethyl alcohol and permitted to dry between tests. To assess the process of habituation to the novelty of the arena, mice were exposed to the apparatus for 5 minutes on 2 consecutive days before the study. The behaviours scored are line crossing, centre square entries, centre square duration, rearing (frequency with which the mice stood on its hind legs in the maze) and freezing time. The results were indicated in table 4.

Evaluation of Anti-schizophrenic Effect on Albino Mice by Morris Water Maze Method:

The Morris water maze is widely used to study spatial memory and learning. Mice were placed on the platform for twenty seconds. Then it was lowered into the water by supporting with hand and bringing it down gently into the water. The animal was left to swim or search for the platform for a maximum of 60 seconds. Mice will learn to search for the platform and climb up. Once mice reach the platform, the timer was stopped and the time was recorded. If it doesn’t find the platform in 60 seconds, then the time for this trial was recorded as one minute. The procedure was repeated for two more trials, starting at a different direction for each trial. Once the animal has completed all three trials, it was dried off with a towel. To begin experimental trials with the water maze, the tank was filled up in such a way that the platform is one inch below the surface of the water. Non-toxic white tempera paint was used to make the water opaque. Each animal should be tested for three consecutive trails, each trial lasting for a maximum of 60 seconds. The animal was monitored until it reaches the platform and the time was recorded which is called as escape latency^20,21. The results were indicated in table 5.

Statistical Analysis:

The results obtained were statistically evaluated. As the procedures performed and the results obtained were in triplicates, the mean along with their standard error of mean (S.E.M) were calculated for drug content and cumulative percentage drug release. Whereas for animal trials, the standard deviation as calculated (S.D).

RESULTS AND DISCUSSION:

Preparation of Quetiapine Solid Dispersions by Physical Mixing and Solvent Evaporation Methods:

Solid dispersions, QTP1 to QTP5 were prepared by physical mixing method using plasdone K-29/32 as carrier in different ratios keeping Quetiapine constant. Similarly, solid dispersions, QTS1 to QTS5 were prepared by solvent evaporation method using plasdone K-29/32 as carrier in different ratios keeping Quetiapine constant. Different formulations with various drug to polymer ratios were placed in table 1.

Table 1: Composition of Quetiapine Solid Dispersions Prepared by Physical Mixing and Solvent Evaporation Methods

S. No	Composition	Drug : Polymer Ratio *(Quetiapine: Plasdone K-29/32)**
1	QTP1	1:0.5
2	QTP2	1:1
3	QTP3	1:2
4	QTP4	1:3
5	QTP5	1:5
6	QTS1	1:0.5
7	QTS2	1:1
8	QTS3	1:2
9	QTS4	1:3
10	QTS5	1:5

Dose of Quetiapine is 25mg

Evaluation of Physical Parameters:

The physical parameter values obtained for various Quetiapine solid dispersions were in the range of good flow characteristics and were given in the table 2. All the solid dispersions prepared were found to be stable and suitable for further studies.

Table 2: Physical Parameters of Quetiapine Solid Dispersions Prepared by Physical Mixing and Solvent Evaporation Methods

Formulation	Angle of Repose (⁰)	Carr’s Index (%)	Hausner’s Ratio	Drug Content (Mean ± S.E.M)
QT (Pure drug)	33	20	1.22	36 ± 0.91
QTP1	30	18	1.19	173 ± 1.05
QTP2	29	17	1.17	170 ± 1.66
QTP3	28	18	1.18	171 ± 1.71
QTP4	28	19	1.19	172 ± 0.98
QTP5	27	18	1.19	172 ± 1.18
QTS1	25	12	1.15	168 ± 1.82
QTS2	24	12	1.14	168 ± 1.54
QTS3	26	13	1.16	169 ± 1.29
QTS4	28	14	1.18	170 ± 1.37
QTS5	28	16	1.18	172 ± 1.42

n=3; S.E.M – Standard error of mean

In-vitro Dissolution Studies of Quetiapine Solid Dispersions:

Dissolution studies were carried on all solid dispersions by using USP paddle method (apparatus II) with 0.1N hydrochloric acid as dissolution medium by maintaining the bath temperature at 37+1^oC and while the paddles were operated at 50 rpm. The dissolution profiles of all solid dispersions were shown in figures 1 and 2. Quetiapine pure drug showed lowest drug release in 60 min. The solid dispersions prepared by physical mixing method showed very less drug release when compared to the dispersions prepared by solvent evaporation technique. Formulation QTS2 containing drug to polymer in 1:1 ratio exhibited maximum drug release of 99.98% in 60 minutes. The dissolution rate enhancement might be due to molecular inclusion of drug molecules into a long chain polymeric material containing hydrophobic and hydrophilic moieties. It was also observed that as the concentration of plasdone K-29/32 increased, the rate of dissolution of solid dispersions was also greatly increased. Recent studies have also supported the benefits of solid dispersion technique to improve drug release²². Certain hydrophilic carriers also enhance the solubility of poorly water soluble drugs^23,24.

Figure 1: Drug Release Profiles of Quetiapine Solid Dispersions Prepared by Physical Mixing Method

Figure 2: Drug Release Profiles of Quetiapine Solid Dispersions Prepared by Solvent Evaporation Method

The DE_30% value obtained for pure drug was 10%. Solid dispersions prepared by physical mixing technique have exhibited dissolution efficiency up to 35% and the dispersions prepared with solvent evaporation method exhibited dissolution efficiency up to 86%. Thus the dissolution rate of Quetiapine solid dispersions prepared by physical mixing method was increased to the extent of 3.33 to 3.50 folds when compared to pure drug. Whereas for solid dispersions prepared by solvent evaporation method at different concentrations of plasdone K-29/32, the dissolution rate was increased by 6.66 to 8.60 folds when compared to the pure drug. Thus the formulation QTS2 prepared by solvent evaporation method using Quetiapine to plasdone k-29/32 in the ratio of 1:1 exhibited highest dissolution rate than any other solid dispersions prepared and hence the said formulation was optimized.

All the formulations including Quetiapine pure drug found to release the drug by first order kinetics. The correlation coefficient (R²) values obtained for all the formulations were in the range of 0.601-0.912 indicating that most of formulations were linear following first order drug release. Hixson-Crowell cube root plots for majority of the formulations including pure drug and marketed formulation were found to be linear. This indicated that the dissolution process depends upon the mass of the drug remained in the dissolution fluids at time rather than surface area as constant. The First order constant and Hixson-Crowell cube root values were given in table 3.

Table 3: Dissolution Parameters of Quetiapine Solid Dispersions

Formulation	% Drug released at 60 min	T₅₀ (min)	DE₃₀%	First Order Rate Constant		Hixson Crowell Cube Root Plot
Formulation	% Drug released at 60 min	T₅₀ (min)	DE₃₀%	K (min^-1)	R²	K (min^-1/3)	R²
QT	11.64	>60	10	0.005	0.601	0.004	0.794
QTP1	45.72	>60	33.3	0.031	0.679	0.136	0.785
QTP2	60.98	49.19	33.3	0.048	0.696	0.135	0.879
QTP3	60.99	49.18	33.3	0.123	0.745	0.167	0.913
QTP4	54.54	55	35	0.161	0.761	0.205	0.930
QTP5	60.98	49.19	33.3	0.182	0.813	0.047	0.914
QTS1	99.72	3	75	0.269	0.858	0.120	0.857
QTS2	99.98	3	86	0.260	0.912	0.148	0.930
QTS3	99.69	3	83.3	0.252	0.842	0.133	0.944
QTS4	88.54	6.5	66.6	0.123	0.870	0.149	0.891
QTS5	88.98	8	72	0.131	0.789	0.141	0.954

R² indicates correlation coefficient, DE is dissolution efficiency

Evaluation of Anti-schizophrenic Effect by Morris Water Maze Method:

The water maze task was developed by Morris. This task can be altered in numerous ways to investigate working memory, reference memory and task strategy. The hippocampus is involved in spatial or relational memory. The water maze specifically tests the spatial memory^30,31.

Atypical antipsychotic medications like Quetiapine provides hope in the management of negative symptoms of schizophrenia^32,33. All the animals were subjected to three trials after single training in normal water without any opaqueness. The mice of all the groups showed a decreased time in finding the hidden maze in second trial. This indicates that the animals have built up memory to some extent. The animals treated with QTS2 have founded the hidden maze in very less time in all the three trials when compared to all other groups indicating enhanced memory. This proves the enhanced solubility and availability of Quetiapine in solid dispersion form when compared to pure form. The results were given in table 5.

Table 5: Effect of Quetiapine Solid Dispersions on Escape Latency in Albino Mice

Group	Treatment	Escape Latency (Mean ± S.D)
Group	Treatment	Trial I	Trial II	Trial III
I	Normal saline (p.o) for 14 days	20±0.45	10±0.30	13±0.44
II	Atropine (5 mg/kg – i.p) for 14 days	45±0.94	35±0.66	38±0.50
III	Atropine (5 mg/kg – i.p) for 14 days + Quetiapine pure drug on 14^th day (25 mg/kg – p.o)	25±0.15	12±0.71	15±0.93
IV	Atropine (5 mg/kg – i.p) for 14 days + QTS2 on 14^th day (25 mg/kg – p.o)	10±0.82	05±0.27	08±0.12

n=5; S.D indicates Standard Deviation

CONCLUSION:

Quetiapine solid dispersions prepared using plasdone K-29/32 in 1:1 ratio by solvent evaporation method (QTS2) showed higher dissolution rate. The optimized formulation was subjected to FTIR analysis, which revealed no drug-excipient interactions. Mice when treated with QTS2 and subjected to open field test, have showed an increase in number of line crossings, centre square entries, rearing and time spent in centre square when compared to all other groups indicating reduced anxiety effect of Quetiapine solid dispersions. QTS2 when subjected to Morris water maze test, a decrease in escape latency time was observed indicating memory maintenance of Quetiapine solid dispersions. Thus from the present study, it was concluded that the Quetiapine solid dispersions prepared with plasdone K-29/32 as polymer by solvent evaporation method (QTS2) showed better drug release and enhanced anti-anxiety and anti-schizophrenic effects.

ACKNOWLEDGEMENTS:

The authors are thankful to the management of Chebrolu Hanumaiah Institute of Pharmaceutical Sciences for their sheer support throughout the work. The authors also express their thanks to M/s. Natco Pharma Ltd. (Hyderabad, India) for their generous gift sample of Quetiapine.

ABBREVIATIONS:

BCS-Biopharmaceutical Classification System, CPCSEA-Committee for the Purpose of Control and Supervision of Experiments on Animals, DE-Dissolution Efficiency, FT-IR-Fourier Transfer Infra Red, i.p-intra peritoneal, p.o-per oral, S.D-Standard Deviation, S.E.M-Standard Error of Mean, USP-United States Pharmacopoeia, UV-Ultra Violet.

CONFLICT OF INTEREST:

The authors declare no conflict of interest.

REFERENCES:

1. Lipinski CA. Avoiding investment in doomed drugs, is poor solubility an industry wide problem. Cur. Drug. Discov. 2001; 4(2): 17-19.

2. Chavda HV, Patel CN, Anand IS. Biopharmaceutics classification system. Sys. Rev. Pharm. 2010; 1(2): 62 – 69.

3. Chauhan B, Shimpi S, Paradkar A. Preparation and evaluation of Glibenclamide-polyglycolized glycerides solid dispersions with silicon dioxide by spray drying technique. Eur. J. Pharm. Sci. 2005;26:219-30.

4. Chiou WL, Riegelman S. Pharmaceutical applications of solid dispersion systems. J. Pharm. Sci. 1971; 60(9): 1281-1302.

5. Punitha S, Srinivasa RG, Srikrishna T, Lakshman KM. Solid dispersions: a review. Research J. Pharm. and Tech. 2011; 4(3): 331-334.

6. Sameer S, Raviraj S, Baghel and Lalit Y. A review on solid dispersion. Int. J. Pharm. Life Sci. 2011; 2(9): 1078-1095.

7. Sneha DB. A review on solid dispersion as a technique for enhancement of bioavailability of poorly water soluble drugs. Research J. Pharm. and Tech. 2014; 7(12): 1485-1491.

8. Martin IM, Ressler KJ, Binder E, Nemeroff CB. The neurobiology of anxiety disorders: Brain imaging, genetics and psychoneuroendocrinology. Psychiatr. Clin. North Am. 2013; 32(3): 549-575.

9. Marcotte E, Pearson D, Srivastava L. Animal models of schizophrenia: a critical review. J. Psychiatry. Neurosci. 2001; 26(4): 395–410.

10. Goldstein JM. Quetiapine fumarate (Seroquel): a new atypical antipsychotic. Drugs. Today. 1999; 35(3): 193-210.

11. Sucheta B, Dyandevi M, Mithun VKP, Rajendra DP. Solubility enhancement of antihypertensive agent by solid dispersion technique. Int. J. Pharm. Life. Sci. 2011; 2(8): 970-975.

12. Jennifer BD, Markus V, Klaus K. Improving Fenofibrate solubility for oral delivery using solid dispersions. Eur. J. Pharm. Biopharm. 2008; 68(2): 283-288.

13. Balaji N, Sai KV, Harikrishna GK. Formulation and evaluation of Simvastatin solid dispersions for dissolution rate enhancement. Research Journal of Pharmaceutical Dosage Forms and Technology. 2011; 2(5): 210-214.

14. Sharda S, Bishambar S, Kirtika M, Monalisha N, Neha K, Shalini M. Solid dispersions: A tool for improving the solubility and dissolution of metronidazole. Int. J. Drug. Deliv. 2013; 5(1): 94-98.

15. Venkates KK, Arunkumar N, Varma PRP, Rani C, Neema G. Formulation and in vitro characterization of valsartan solid dispersions. Research J. Pharm. and Tech. 2009; 2(3): 502-506.

16. Appa RB, Shivalingam M, Kishore RYV, Somesekhara R, Rajesh K, Sunitha N. Formulation and evaluation of aceclofenac solid dispersions for dissolution rate enhancement. Int. J. Pharm. Sci. Drug. Res. 2010; 2(1): 146-150.

17. Brown RE, Corey SC, Moore AK. Differences in measures of exploration and fear in MHC-congenic C57BL/6J and B6-H-2K mice. Behav. Genet. 1999; 26(3): 263-271.

18. Carrey N, McFadyen MP, Brown RE. Effects of chronic methylphenidate administration on the locomotor and exploratory behaviour of prepubertal mice. J. Child. Adolesc. Psychopharmacol. 2000; 10(4): 277-286.

19. Haja SS, Sindhura S, Anusha S, Jaya PP, Sengotuvelu S, Sivakumar T. Evaluation of anti-anxiety activity of alcoholic extract of Cyndon dactylon linn. in experimental animal models. Research J. Science and Tech. 2012; 4(5): 197-202.

20. Nunez J. Morris water maze experiment. J. Vis. Exp. 2008; 19(4): 1-2.

21. Monirul I, Ramanjaneyulu J, Veeresh BD, Mohibul H, Narayana SVB. Studies on memory enhancing property of bravobol- a polyherbal formulation in experimentally induced alzheimers disease in experimental animals. Asian. J. Res. Pharm. Sci. 2015; 5(2): 86-90.

22. Dharna A, Neelam S, Sukhbir S, Sandeep A. Solid dispersions: a review on drug delivery system and solubility enhancement. Int. J. Pharm. Sci. Res. 2013; 4(5): 2094-2105.

23. Srikanth MV, Murali MB, Sunil SA, Sreenivasa RN, Praveen KK, Ramana MKV. Studies on the effect of hydrophilic carriers in the dissolution rate enhancement of poorly soluble drug, Bicalutamide. Research J. Pharm. and Tech. 2010; 3(2): 592-595.

24. Kranthi KRM, Narasimha RB, Ravindra RK. Study on effect of excipients in enhancing the solubility of Nateglinide by solid dispersions. Asian. J. Pham. Res. 2012; 2(4): 144-147.

25. Perry E, Perry R. Acetylcholine and hallucinations: disease-related compared to drug-induced alterations in human consciousness. Brain. Cognition. 1995; 28(2): 240–258.

26. Minzenberg M, Poole J, Benton C, Vinogradov S. Association of anticholinergic load with impairment of complex attention and memory in schizophrenia. Am. J. Psychiatry. 2004; 161(2): 116–124.

27. Barak S. Modeling cholinergic aspects of schizophrenia: focus on the antimuscarinic syndrome. Behav. Brain. Res. 2009; 204(4): 335–351.

28. Blanchard DC, Griebel G, Blanchard RJ. Mouse defensive behaviors: Pharmacological and behavioral assays for anxiety and panic. Neurosci. Biobehav. Rev. 2001; 25(2): 205-218.

29. Choleris E, Thomas AW, Kavaliers M, Prato FS. A detailed ethological analysis of the mouse open field test: effects of diazepam, chlordiazepoxide and an extremely low frequency pulsed magnetic field. Neurosci. Biobehav. Rev. 2001; 25(3): 235-260.

30. D'Hooge R, Deyn PP. Applications of the Morris water maze in the study of learning and memory. Brain. Res. 2001; 36(1): 60-90.

31. Lakshmi K, Karishma SK, Chandrasekhar GNSS, Narendrababu A, Bhargav KN. Terminalia chebula Retz improve memory and learning in Alzheimer’s model: (experimental study in rat). Research J. Pharm. and Tech. 2018; 11(11): 4888-4891.

32. Silveri K, Akondi BR, Swathi M. Genestein, a phytoestrogens for the treatment of schizophrenia. Int. J. Sci. Eng. Res. 2014; 4(7): 296-321.

33. Jayanth PC, Prasanna KK, Niranjan BM. Evaluation of nootropic potential of Krill oil in Diazepam induced amnesic mice. Res. J. Pharmacology and Pharmacodynamics. 2016; 8(3): 111-114.

Received on 07.10.2019 Modified on 27.11.2019

Research J. Pharm. and Tech 2020; 13(5):2359-2365.

DOI: 10.5958/0974-360X.2020.00424.2

Group	Treatment	Parameters (Mean ± S.D)
Group	Treatment	No. of Line Crossings	No. of Centre Square Entries	Centre Square Duration (in sec)	No. of Rearing Signs	Freezing Time (in sec)
I	Normal saline (p.o) for 14 days	51±1.97	02±1.64	24±1.47	10±1.97	30±1.18
II	Atropine (5 mg/kg – i.p) for 14 days	25±2.01	0	0	07±1.42	240±1.45
III	Atropine (5 mg/kg – i.p) for 14 days + Quetiapine pure drug on 14^th day (25 mg/kg – p.o)	85±1.73	03±1.83	41±1.61	25±1.64	45±1.29
IV	Atropine (5 mg/kg – i.p) for 14 days + QTS2 on 14^th day (25 mg/kg – p.o)	103±1.81	05±1.51	72±1.25	36±1.39	25±1.77