INTRODUCTION:

Gastro-retentive Dosage Forms (GRDF) are dosage forms specifically formulated to be retained in the stomach. Floating Drug Delivery Systems (FDDS) represent a type of gastro-retentive dosage forms employed for prolonging gastric residency. Extended oral release of gastrointestinal dosage forms provides several benefits for medications that are absorbed in the upper GIT, as well as for those that exert their effects locally within the stomach.

Lafutidine has not been included in any pharmacopoeias. It is utilized as an antiulcer manager owing to its classification as a new generation H2 receptor blocker. Lafutidine, when orally administered, is both safe and efficient in alleviating symptoms of oral burning. Lafutidine effectively inhibits acid secretions, thus acting against esophageal lesions caused by acid reflux. Previous research indicates that lafutidine therapy is both effective and well tolerated in patients with Acid Peptic Disorders (APDs). Lafutidine exhibits a biological half-life of approximately 2-3 hours, showing site-specific absorption in the upper GIT and resilence in gastric pH. Lafutidine’s attributes render it ideal for the design of prolonged DDS that can release the medication in the gastric contents of the stomach, thereby guaranteeing optimal bioavailability and potent therapeutic outcomes.^1,2,3,4,5

Natural polymers offer numerous benefits such as biocompatibility, natural origin, safety, non-toxicity, cost-effectiveness, biodegradability, and their applications are expanding in the pharmaceutical industry. Various natural polymers are employed to facilitate the DDS to act as drug carriers, aiming to improve therapeutic efficacy. An effort is being made in the present research to create a gastroretentive DDS (ideally through flotation) by employing diverse polymers (natural – Hibiscus gum, Okra gum, lanneacoromandelica gum [LCG] and synthetic – Polyox WSR 303) and effervescent mixtures for the formulation development of Lafutidine regioselective Hydrodynamically Balanced controlled release drug delivery^6,7,8.

MATERIALS AND METHODS:

Materials:

Lafutidine gift sample from Mylan, Polyox, Sodium bicarbonate, Citric acid, Magnesium stearate were purchased from S.D fine Chemicals.

Analytical Method:

Instrument used:

Shimadzu (UV-1700) UV-visible spectrophotometer.

a) Identification of λ_max:

A 0.1N hydrochloric acid (HCL) solution was created with a drug concentration 10µg/mL, and its UV spectrum was analyzed utilizing a Double beam UV/VIS spectrophotometer. The solution was scanned within the range of 200 – 400nm.

b) Development of Standard Plot:

Prepare stock solution of pure drug 1mg/1ml. from stock solution prepare a range of standard concentrations that include 2, 4, 6, 8, 10µg/ml per ml of solution. The dilutions mentioned above were analyzed for absorbance at 236nm using a UV-Spectrophotometer with 0.1N HCL as the blank solution. subsequently a calibration plot was created and the degree of linearity was assessed using the square of the correlation coefficient (R2) obtained from least-square linear regression analysis⁹.

Extraction of H. rosa-sinensis mucilage:

The newly harvested H. rosa-sinensis Linn. leaves were gathered and rinsed with H₂O to eliminate any Soil and rubble. Then the leaves were ground into a powder and soaked in water for 5-6hours. Following this, they were cooked for half an hour and allowed to rest for one hour to guarantee the complete removal of mucilage into the water. Then it was isolated by passing it through a bag made of muslin cloth with multiple to separate the marc from the solution's layers. Three times the amount of filtrate was added with acetone to induce the precipitation of the mucilage. The mucilage was extracted, dried in an oven at 50°C, and subsequently stored in a desiccator for future use.¹⁰

Extraction of okra mucilage:

1. The conventional method for extracting okra mucilage consists of harvesting unripe okra pods, slicing them, and placing the crushed pods into a beaker containing water. The mixture is then soaked for a duration of 12 to 24hours. before the swollen pods are squeezed and the mucilage is extracted using muslin cloth.

2. The okra mucilage was isolated by subjecting the above extraction to centrifugation and treating it with either acetone while continuously stirring to isolate the mucilage. The okra mucilage is extracted and subsequently gathered by passing it through muslin cloth for filtration. The gathered mucilage is initially dried in the shade for a duration of 24hours, followed by drying at a temperature range of 35–45°C in a hot air oven until a stable weight is reached. To prevent moisture absorption, the mucilage is stored in a desiccator.¹¹

Extraction and purification of Lannea Coromandelica gum from raw gum:

Gum was sourced from the L. coromandelica plants. After being collected, the gum was subjected to drying in an oven at 60° to remove impurities. Later on, the gum was separated from the solution using ethanol. The precipitate obtained was subsequently isolated, dehydrated in an oven set at 40°C, and pulverized with a high-speed mechanical blender. After sifting through mesh no. 80, the resulting powder was stored in a descicator for future use¹².

Preparation of Lafutidine floating tablets:

The formulation of Lafutidine tablets was accomplished through the direct compression method, incorporating polymers such as Hibiscus gum, Okra gum, Mangifera Indica, and Polyox WSR 303. The drug, in addition to excipients like MCC, NAHCO₃, citric acid, and magnesium stearate, was meticulously mixed and compressed¹³.

Table1: Composition of trial formulations

S.No

Excipients

FORMULATION CODE QTY : mg/tab

LF1

LF2

LF3

LF4

LF5

LF6

LF7

LF8

LF9

LF10

LF11

LF12

API

10mg

Avicel 102

195mg

185mg

175mg

195mg

185mg

175mg

195mg

185mg

175mg

195mg

185mg

175mg

Hibiscus gum

10 mg

20 mg

30 mg

10mg

Okra gum

10 mg

20 mg

30 mg

10mg

LCM

10 mg

20 mg

30 mg

10mg

PEO WSR 303

10 mg

20 mg

30 mg

Sodium Bicarbonate

25 mg

Citric Acid

5 mg

Mg. Stearate

5mg

Total

250mg

Effect of sodium bicarbonate concentration:

The buoyancy of in vitro systems was improved by using NAHCO₃ and citric acid as gas-generating agents. The effect of sodium bicarbonate on buoyancy was noted. At a concentration of 5% w/w, the tablets were unable to float. The lack of gas generation may be the reason why the formulation is struggling to stay afloat. The carbon dioxide bubbles generated from the reaction between NAHCO₃ and the acid medium were trapped inside the gel produced by polymers, resulting in a density lower than 1g/cm³, which allowed the tablet to remain buoyant. However, when the concentration of NAHCO₃exceeded 10% w/w, the tablets could not maintain their physical structure for 24hours. The reason for this could be an overabundance of carbon dioxide causing a disturbance in the huge tablet. As a result, buoyant tablets were created with a 10% w/w NAHCO₃concentration¹⁴.

Impact of varying citric acid levels:

The stomach pH increases to around 3.5 when food is present. At this pH, the floating lag time could potentially be prolonged or the tablet might not float at all. Citric acid was added to the formulation in order to guarantee the buoyancy of the tablet by creating an acidic environment for Sodium bicarbonate. Tablets containing 1% w/w citric acid did not float at all. However, as the citric acid concentration was raised to 2%, the floating lag time decreased. Tablets began to disintegrate when the concentration of citric acid surpassed 2% w/w, resulting in inadequate matrix formation to contain the gas generated by the effervescent mixture, which was attributed to diminished tablet integrity. Hence, buoyant tablets were formulated with a citric acid concentration of 2% w/w.^15,16.

Evaluation Parameters:^17,18,19,^20,21,22,

Precompression parameters:

An evaluation of the bulk and tapped density of the formulation powder blends was carried out prior to compression, resulting in the determination of compressibility index and Hausner’s ratio. Additionally, the powder blend's flow properties were assessed through the measurement of the angle of repose.

Assessment of Floating Tablets:

Parameters for post-compression:

Quality control examinations were conducted on the tablets produced, which included tests for weight variation, hardness, thickness, friability, and assessment of content uniformity.

Weight variation:

Ten tablets were randomly selected from each batch and individually weighed to calculate the average weight. A comparison was made between the weight of each tablet and the average weight. Subsequently, the percentage difference in weight was calculated and cross-checked against the USP standards.

Thickness:

Tablet thickness plays a crucial role in replicating the desired appearance. The average thickness of tablets was determined and reported along with any deviations.

Hardness:

Friability:

The Roche friabilator was employed for the purpose of performing the friability test. Ten tablets were weighed and subjected to both attrition and shock inside a plastic chamber that rotated at 25rpm, causing the tablets to drop at a distance of 6 inches with each revolution. Following 100 revolutions, the tablets underwent a de-dusting process and were subsequently reweighed to determine the percentage of friability.

Tablet density:

The tablet's ability to float is heavily influenced by its density. Should the tablet have a lower density than the gastric fluid (1.004g/cc), it will float. The density is calculated through a particular formula.

D=m/v

V=πr ² h

V= Tablet volume (cc), r= tablet radius (cm), h= tablet thickness (g/cc), m= weight of tablet (g).

Determination of drug content:

Ten tablets were analyzed to determine their drug content. The tablets were pulverized into a fine powder, and a quantity equal to the mass of a single Lafutidine tablet was precisely measured and added to a 100ml volumetric flask containing 50ml of water. The blend was subsequently permitted to rest in order to guarantee the full solubility of the medication, and then topped up to the desired volume with water. The solution obtained was appropriately diluted, and the absorption was assessed utilizing a double beam spectrophotometer. The concentration of the drug was subsequently determined using the Standard plot.²³

Invitro buo yancy studies:^24,25,26,

The buoyancy in vitro was evaluated through the measurement of the delay in floating. Tablets were placed in a beaker filled with 200ml of 0.1 N HCl. The Floating Lag Time (FLT) was measured as the period it took for the tablet to rise to the surface, while the Total Floating Time (TFT) was recorded as the duration the tablet stayed afloat.

Water uptake determination or swelling study:

The hydration rates of formulations were determined by immersing tablets in a test medium to analyze the relationship between drug release and polymer hydration rates. The tablets were positioned in dissolution apparatus baskets that were rotating at a speed of 50rpm, using simulated gastric fluid for the model drug at a temperature of 37±0.5ºC. After 1, 2, 3, 4, 5 and 6 hours, each sample was removed, dried, and weighed. The trial was carried out three times for every time interval, and the rise in mass caused by absorbed fluid (Q) was computed at each time interval utilizing a designated formula.

100 (Ww-Wi)

Q = ---------------

Where

The mass of the sample after hydration is represented by Ww.

The initial weight of the dry sample is denoted as Wi.

Invitro Dissolution Studies:

An in vitro dissolution study was performed using a United States Pharmacopeia (USP) type II (paddle) apparatus, which operated at a rotational speed of 100 revolutions per minute (rpm). The dissolution medium consisted of 900ml of 0.1 N HCl, and the temperature was meticulously controlled at 37⁰C±0.5⁰C. At designated time points throughout a 12hour duration, a 10ml portion of the mixture was withdrawn from the dissolution device and substituted with new dissolution fluid that had been preheated. The samples underwent filtration using Whatman filter paper and were suitably diluted with 0.1N HCl. Later on, the solutions' absorbance was measured at 236nm with a UV spectrophotometer.²⁷

Stability studies:^28,29

An accelerated storage condition at a temperature of 40° ±2° C and 75% ±5% RH in a humidity chamber was utilized to conduct a stability study of the optimized batch1. This research utilized FTIR Spectra to assess the variations in evaluation parameters and the in vitro release profile over a duration of three months, with assessments conducted at 30-day intervals.

RESULTS AND DISCUSSION³⁰

The current study explores the use of Lafutidine as an effective treatment for ulcers, showing promise in reducing dosing frequency and improving compliance. Lafutidine has been developed into floating tablets for gastroretention, allowing for sustained and controlled release over a prolonged duration.

Analytical Method:

Table 2: Calibration curve of lafutidine

Concentration	Absorbance (nm)
0	0
2 µg/ml	0.137
4 µg/ml	0.258
6 µg/ml	0.395
8 µg/ml	0.527
10 µg/ml	0.659

Figure1: Calibration curve of lafutidine

Evaluation properties of Powder blends of different batches

Table 4: Blend characterization of formulations of trial batches.

Formulation	BD (gm/cm³)	TD (gm/cm³)	CI (%)	HR	Angle of repose (θ)
F1	0.314	0.348	12.6	1.144	27.8
F2	0.316	0.348	12.06	1.137	28.6
F3	0.318	0.350	12.43	1.136	29.4
F4	0.309	0.356	13.02	1.129	28.3
F5	0.308	0.362	13.11	1.132	27.5
F6	0.321	0.354	12.89	1.145	29.4
F7	0.317	0.358	13.21	1.137	29.5
F8	0.315	0.362	11.94	1.127	28.6
F9	0.322	0.36	13.05	1.138	29.3
F10	0.318	0.366	13.11	1.143	28.4
F11	0.326	0.365	13.42	1.141	29.2
F12	0.329	0.53	13.28	1.146	27.6

Characterization of prepared Formulations:

Table5: physicochemical properties for Formulation

F. No	Weight variation(mg)	Thickness (mm)±SD	Density(g/cc)	Hardness(kp)±SD	Friability (%)	Drugcontent (%) ±SD
LF1	240-255	2.4±2-9	0.897	3.82±0.01	0.52	99.89±0.73
LF2	250-260	2.2±2.8	0.897	3.81±0.05	0.61	100.56±0.78
LF3	245-255	2.6±2.9	0.880	3.87±0.11	0.54	100.88±0.54
LF4	250-254	2.3±2.5	0.897	3.82±0.10	0.59	99.98±0.28
LF5	247-260	2.5±2.6	0.872	3.91±0.02	0.68	100.21±0.26
LF6	255-259	2.6±2.7	0.895	3.84±0.04	0.58	99.67±0.42
LF7	243-250	2.2± 3	0.884	3.88±0.02	0.59	100.32±0.51
LF8	246-260	2.4±2.6	0.888	3.87±0.12	0.62	100.65±0.12
LF9	248-259	2.5±2.8	0.865	3.95±0.14	0.52	100.81±0.92
LF10	244-255	2.2±2.9	0.895	3.84±0.06	0.64	100.97±0.24
LF11	255-260	2.8±3	0.840	3.16±0.08	0.51	99.98±0.18
LF12	240-255	2.1±2.7	0.882	3.34±0.19	0.59	99.89±0.16

In Vitro Buoyancy Studies:

Table6: Characterization of floating properties

F. NO	Floating lag time(seconds) ± SD	Floating time(hrs)	Matrix Integrity
LF1	120 ± 0.22	4	-
LF2	115 ± 0.19	6	-
LF3	100 ± 0.23	7	+
LF4	127± 0.29	4	-
LF5	90 ± 0.32	6	+
LF6	82 ± 0.38	7	+
LF7	94± 0.27	6	-
LF8	99± 0.35	8	+
LF9	85± 0.28	10	+
LF10	75± 0.35	7	+
LF11	70± 0.39	9	+
LF12	60 ± 0.26	11	+

Swelling studies:

Table7: Selling Index for formulations

S No.	F. NO	%Ofswelling
S No.	F. NO	1 hr	2 hrs	3 hrs	4 hrs	5 hrs	6 hrs
1	LF1	The tablets displayed the greatest degree of erosion.
2	LF2	The tablets displayed the greatest degree of erosion.
3	LF3	0.82	0.99	1.49	2.06	2.37	2.51
4	LF4	The tablets displayed the greatest degree of erosion.
5	LF5	1.15	2.05	2.17	2.26	2.41	2.86
6	LF6	1.86	2.32	2.39	2.43	2.56	3.07
7	LF7	1.99	2.28	2.46	2.64	2.90	3.86
8	LF8	2.22	2.41	2.58	2.78	3.04	3.28
9	LF9	2.29	2.56	2.69	2.91	3.18	3.99
10	LF10	2.48	2.57	2.67	3.18	3.82	4.31
11	LF11	2.75	2.90	3.23	3.46	3.84	4.39
12	LF12	2.50	2.85	3.40	3.69	3.84	4.79

Dissolution profiles for formulations (LF1 to LF12) as polymers.

Table8: Invitro drug release profile for F1 to F6.

Time	Cumulative % Drug released
	LF1	LF2	LF3	LF4	LF5	LF6
1	35.98	33.19	30.75	50.62	39.70	28.31
2	60.11	49.82	48.77	62.30	48.33	34.76
3	80.17	69.06	57.15	77.15	56.97	44.53
4	91.33	78.31	65.17	85.91	67.12	52.03
6		93.04	73.02	92.65	84.80	69.36
8			90.52		95.34	77.51
10						96.10
12

Table 9: Invitro drug release profile for LF7 to LF12.

Time	Cumulative % Drug released
	LF7	LF8	LF9	LF10	LF11	LF12
1	18.48	25.87	15.25	37.09	14.65	18.97
2	28.77	36.86	21.88	44.94	22.84	21.76
3	36.80	47.55	29.46	59.82	37.38	32.43
4	43.08	54.18	34.69	67.15	44.7	46.76
6	50.58	63.25	53.40	74.65	51.68	53.28
8	95.60	88.23	72.17	93.19	60.58	65.23
10		96.51	89.84		97.03	79.78
12			97.62			96.67

Figure 2: In vitro drug rele ase study of F1 to F12 formulations.

Evaluation of drug release kinetics:

Table10: Evaluation of drug release kinetics

Batch no	R²values (Correlation coefficient)
	Zero order	First order	Higuchi	Korsmeyer- Peppas
				R² value	n value
F12	0.977	0.825	0.964	0.966	0.682

Figure: Zero order plot for F12 formulation Figure: First order plots for F12 formulation

Figure3: Korsmeyer-peppas plot for F12 formulation Figure4: Higuchi plot for F12 formulation

Stability studies: FTIR studies:

The physicochemical compatibilities of the optimized formulations were also tested by FTIR. IR spectra were showed below

Figure5: FTIR Spectra of Pure Drug

Figure6: FTIR Spectra of Optimized formulation

Accelerated Stability Studies:

Table11: InVitro Drug Release of Optimized Formulation

Time	Drug Release Initial (F12)	Drug Release After 12 Weeks (F12)
1	18.97	15.35
2	21.76	19.79
3	32.43	30.54
4	46.76	43.35
6	53.28	55.74
8	65.23	69.65
10	79.78	82.73
12	96.67	94.27

Figure 7: In-Vitro Drug Release for Optimized formulation After 3 Months

DISCUSSIONS:

The flow properties of the blend intended for tablet compression were assessed; the findings for the compression tablet blends were presented in Table 4. All formulations met the acceptable limits for both bulk density and tapped density. The Carr's index and Hausner's ratio were observed to be between 12 and 13, and 1.12 to 1.14, respectively, indicating that the blend exhibits good flow properties and compressibility. All formulations exhibited an angle of repose between 26 and 30, demonstrating excellent flow characteristics. The weight fluctuated between 240-260, meeting pharmacopoeial standards. The tablets measured 2-3 mm in thickness. The tablet density fell within acceptable parameters. The mechanical strength of various formulations was determined to be below 3kp, demonstrating acceptable hardness. The friability of all formulations was recorded at less than 1%, indicating a strong mechanical resistance of the tablet. Additionally, the drug content was determined to be within acceptable limits. The buoyancy was found to be within limits. The formulations that demonstrated adequate floating time and matrix integrity were selected for In vitro drug release studies, while those that did not meet these criteria were discarded. The investigation on swelling was conducted on formulations incorporating Hibiscus, Okra, LCM, and Polyethylene oxide as polymers. It was deduced that formulation LF12 exhibited the highest swelling indices consistently during the entire study duration1. The increased viscosity of the polymers may account for this observation. The LF12 attained the maximum swelling indices (4.79) at the 6th hour. As the polymer ratio increased, there was a gradual rise in the swelling indices over the course of the study. However, after 6 hours, the tablets ceased to swell and began to erode. The optimized formulations underwent assessment for drug release kinetics through zero order, first order, Higuchi, Korsmeyer-Peppas model, and the R2 values for all formulations were recorded in table 10. The Lafutidine medication, which was developed using LCM and PEO, demonstrated zero order drug release kinetics. The correlation coefficient (R2) values of 0.977 (F12) indicate that the drug release rate is not influenced by its concentration. Furthermore, it exhibited Korsmeyer-Peppas release kinetics, with correlation coefficient (R2) values of 0.966 (F12) and an n value ranging from 0.45 to 0.89, suggesting Anomalous diffusion or non-Fickian diffusion, where both diffusion and erosion govern the release rate. No notable difference was detected from FTIR Studies in the optimized process when carried out every 30 days after 3 months at a temperature of 40 ± 2ºC. No notable alteration was detected in the buoyancy and invitro drug release after 3 months when tested at 40 ± 2ºC, with an interval of 30 days.

CONCLUSION:

According to the latest research findings, the blend of macro molecules (both Natural and Synthetic polymers) has been shown to provide benefits in preserving the structural integrity and floatability of tablets. A successful formulation of Gastro retentive tablet dosage form of Lafutidine was achieved using PEO WSR 303, Lannea coromandelica gum. The dynamic FDDS, which relies on gel forming polymers and sodium bicarbonate as the gas generating agent, shows great potential as a formulation for achieving gastro retentivity. Out of the different Gastro retentive formulations that were analyzed, formulation (LF12) showed the most favorable outcomes in relation to the necessary % cumulative drug release, Floating lag time, and total floating time, establishing it as the optimal formulation. LF12 comes after Zero order release, Non-Fickian Diffusion, and demonstrates favorable retention properties.

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Received on 13.11.2024 Revised on 18.02.2025

Accepted on 31.03.2025 Published on 23.04.2025

Available online from April 26, 2025

Asian J. Pharm. Tech. 2025; 15(2):107-115.

DOI: 10.52711/2231-5713.2025.00018

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a) Identification of λmax:

Table5: physicochemical properties for Formulation

Figure 2: In vitro drug rele ase study of F1 to F12 formulations.

Evaluation of drug release kinetics:

Table10: Evaluation of drug release kinetics

Figure: Zero order plot for F12 formulation Figure: First order plots for F12 formulation

a) Identification of λ_max: