INTRODUCTION:

The temperature sensitivity of thermolabile drug product, particularly potency, led to the development of storage and cold chain requirements for such drugs [1]. Most of thermolabile drugs are unstable at refrigeration and at normal storage conditions and thus proving difficult to maintain activity and shelf life. To counter balance the thermal instability of these products lyophilization is commonly used, but this method has its inherent limitations such as low solid content, incomplete solidification, skin formation, poor ice crystal formation and melt back [2]. The lyophilized products should strictly be stored in facilities such as liquid nitrogen, dry ice or mchanical refrigeration [3].

Bendamustine hydrochloride (BH) is an alkylating antitumor agent mainly showing effect due to the uncross-linking of DNA strands which show antineoplastic and cytocidal effects [4]. It is used for the treatment of patients with chronic lymphocytic leukaemia. This drug is available as water soluble microcrystalline powder with amphoteric properties and it exhibits polymorphism [4]. BH being a weak base has pH dependent solubility and is more soluble in acidic media. BH is a very unstable drug and undergoes hydrolytic and photodecomposition type of degradation [5, 6]. These reactions are accelerated with elevated temperatures. In order to accomplish desired stability BH is often manufactured as a lyophilized form and is stored in light protective glass bottles. Degradation of BH products may occur during lyophilization, storage and upon reconstitution in water [7]. The physico-chemical characteristics of lyophilized form of BH are pertinent for the drug product stability and performance. The reconstitution of lyophilisate in water is troublesome and requires 15 min - 30 min. The lengthy exposure of BH to water during the reconstitution process results in impurity formation and increased potential for loss of activity [8].

The lengthy processing times of lyophilization may increase the drug-water contact time providing favourable condition for hydrolytic degradation to occur [9, 10]. There have been some alternative techniques reported to replace lyophilization and amongst which evaporative foam drying (EFD) appeared to be the best option [11]. EFD is a mass transfer process consisting of the removal of water or another solvent by evaporation from a liquid. This process is a modified version of freeze drying wherein prefreezing is eliminated and a foaming step, which enhances the drying ability and reduces drying time, is incorporated. The EFD concentrates a solution by evaporation of solvent below its normal boiling point under reduced pressure. The reduced pressure decreases the boiling temperature of the solution. The energy supplied to the system compensates self-cooling effect of evaporation which occurs either with or without boiling. Foam formation occurs during boiling accelerates drying. The difference between the product temperature and the condenser temperature acts as driving force for the rapid removal of the solvent.

We undertook the present study on the stabilization of bendamustine hydrochloride in sugar-phosphate composites using EFD as an alternative approach to improve its stability at normal storage condition.

MATERIALS AND METHODS:

Materials

Bendamustine hydrochloride was obtained from Panacea Biotech Ltd., Mumbai. Sucrose and trehalose were gift samples from Himedia Laboratories Pvt. Ltd., Mumbai. Polyvinyl pyrrolidone K30 (PVP) was a gift sample from Sisco Research Laboratories Pvt. Ltd., Mumbai. Sodium mono phosphate and potassium mono phosphate were purchased from Merck Limited, Mumbai. Pluronic F-108^®NF, Pluronic F-188^®NF and Pluronic F407^®NF were gift samples from BASF Corporation, Mount Olive, New Jersey, USA.

Methods

Effect pH and Temperature

The buffered BH solutions containing formulation components were prepared aseptically. BH, 1 mg/mL, was dissolved in buffer solutions (pH 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0, separately). Accurately 5 mL of each solution was stored in rubber stoppered, crimped glass vials wrapped in aluminum foil. The BH in optimized buffer solutions in vials were stored at 2 -4 °C, 4-10 °C, 10-20 °C and 20-30 °C for 4 days. The BH was in aqueous solutions was estimated at the end of every 24 h using HPLC using UV detector at λ_max 231 nm.

Foamability and Foam Stability

Pluronic foaming agents were screened for foamability and foam stability using modified Ross-Miles test. Aqueous pluronic solutions at 0.4%w/v, 0.6%w/v and 0.8%w/v strengths were prepared in 500 mL volumetric flasks. Set up included a graduated cylindrical glass tube of 85 cm length and 2.4 cm internal diameter (capacity 500 mL) and a separating funnel of 0.5 cm internal diameter. The 50 mL of test solution was initially filled in a cylindrical tube, arranged perpendicular to working table at room temperature. Accurately measured 200 mL of test solution was added to the cylindrical tube through the separating funnel to produce 250 mL foamy solution from the height of 70 cm, which was taken as initial foam height. The height of the foam was measured at 5 min interval up to 30 min, followed by 15 min interval up to 120 min. Foam stability was calculated as the ratio of initial height of the foam, (H₀), to the height of the foam column after t min, (H_t).

The foamability and foam stability of all pluronics was determined. Similarly, the effect of presence of sucrose and trehalose at 30 %w/v on the foamability and foam stability of optimized PF aqueous solutions was investigated.

RP-HPLC Method

The RP-HPLC method was selected for quantitative estimation of BH from the prepared EFD formulation. The chromatographic variables such as mobile phase, flow rate and solvent ratio were studied and the resulting chromatograms were recorded [12a]. RP-HPLC was performed using Shimadzu Corporation, Tokyo, Japan equipped with PU 2080 Pump and UV 2075 Detector. Akya Tech HIQ Sil C₁₈reverse phase analytical column (250 nm x 4.6 mm, 5 μm) was used. The ambient temperature was maintained throughout the study. The data were analyzed using Jasco Browin (version 1.50, build 16) software. Chromatographic analysis performed using mobile phase consisted of 0.1% trifluroacetic acid in water: acetonitrile (50:50), pH 2.0, pumped at a flow rate of 1 mL/min. Sample injection volume was 20 μL and detection wavelength was 231 nm. The analytical runs were carried out at ambient temperature. The mobile phase containing 0.1% trifluroacetic acid in water: acetonitrile (50:50), was tried for proper elution of BH on the system as specified above. The mobile phase was filtered through 100 μ nylon filter and degassed ultrasonically for 20 min. In the series of 10 mL volumetric flasks, 0, 2, 4, 6, 8, 10 mL (10 μg/mL) solutions of BH were added and the final volumes were

made up to 10 mL by addition of mobile phase. Accurately 20 μL of sample solution was injected into the injection port of chromatographic system having fixed volume loop injector. Chromatograms were noted and area under curve was plotted against concentration to construct calibration curve.

EFD Process Protocol

The EFD process has two main steps namely primary and secondary drying. The essential difference between EFD and lyophilization is that the product in earlier process is not frozen and drying at initial stages occurs by boiling the samples in the vials above 0°C but well below normal boiling point of solutions under vacuum, and not by sublimation from ice [13].Rationally designed 2 mL aqueous compositions containing 20%w/v sugar, 0.6%w/v surfactant and 50 mg/mL BH was subjected to EFD (vials, capacity 10mL) in Labconco (FreeZone^® 2.5, UK) lyophilizer. Three different protocols were set on the basis of product characteristics in each cycle, Table 1. The temperature of the condenser was set to -50 °C. The protocols were compared and efficiency was optimized on the basis of foam height, % residual moisture and BH content.

Table 1: EFD cycle protocols used for optimising process efficiency

Time (min)	Shelf Temperature (°C)	Pressure (mBar)
Time (min)	Shelf Temperature (°C)	Protocol – I	Protocol – II	Protocol -III
Primary drying
30	0 - 10	1.650	1.650	1.650
30		1.370	1.370	1.370
30		1.140	1.140	1.140
30		0.940	0.940	0.940
30		0.770	0.770	0.770
30		0.630	0.630	0.630
30		0.520	0.520	0.520
30		0.420	0.420	0.420
30		0.340	0.340	0.340
30		0.280	0.280	0.280
30		0.160	0.160	0.160
990		0.016	0.016	0.016
Secondary drying
120	30	0.016	0.016	0.016

During primary drying 2 mL aliquots of the different compositions were placed in natrium-calcium tubular glass vials (10 mL capacity) and partially sealed with dry vented butyl rubber closures. The vials were placed on a shelf in chamber of a lyophilizer and processed as per optimized protocol. Primary drying was followed by secondary drying of foamy structures for further removal of bound residual water. The vials were fully stoppered under vacuum. The finished product vials were protected from light by packing in opaque boxes and stored in the dark room at room temperature for further analysis.

Optimization of Composite mixtures

Rationally design of formulations for EFD was based upon combination of four kinds of excipients namely a glass-forming agent sucrose and trehalose, stabilizers sodium and potassium salts of phosphate, a non-ionic foaming agent Pluronic F108^® and a polymer PVP as a foam stabilizer. The aqueous systems (pH 2.0) for EFD were prepared in a series of mixtures containing 25 mg BH with stabilizers as given in Table 2. Accurately measured 2 mL aliquots of these solutions were filled into clean and dried vials. The vials were partially sealed with dry vented butyl rubber closures and the solutions were dried using optimized protocol. The dried foams were sealed under vacuum.

BH Estimation

The BH content in all foam dried products was determined using RP-HPLC method after reconstitution. The relative amounts of BH in each sample were assayed in triplicate. Product samples were reconstituted with distilled water to obtain BH concentrations of 50 mg/mL. Accurately measured 20 μL of sample was injected at a flow rate of 1 mL/min and UV detection was carried out at λ_max231nm.

Residual moisture

Residual moisture contents in all foam dried products were determined using a Karl Fischer titrator (Vigo Matic, MD) [14]. Anhydrous methanol (20 mL) was transferred to titration vessel and titrated to the end-point. Distilled water (10 μL) was used to standardize the Karl Fischer reagent. Accurately weighed foam dried samples were suspended in anhydrous methanol and titration was carried out to the electromagnetic end point.

Reconstitution time

Reconstitution times of the EFD products were determined by Thiemann method [15]. Each sample was reconstituted with 1mL of sterile water for injection while putting the solution flow onto the inside of the vial. The vials were shaken horizontally at a distance between 6 inches on hard surface till solution is formed. The vials were inspected visually by measuring the solution time without visible aggregates.

Digital light microscopy

Foam dried products were analyzed for preliminary characteristics of glass using light microscopy (ModelBA310 POL Trinocular, Motic China Group Co. Ltd.) (16). Crushed foam powders were placed on a glass slide under a drop of cedar wood oil and covered with a cover slip. The oil prevents the moisture absorption as well as improves resolution power of the objective lens. Dried samples were viewed under 100× magnification, and the photomicrographs were captured using a Hyper HAD colour video camera and stored electronically using Motic images 2000^® version 1.3 software (National Optical and Scientific Inc., San Antonio, Texas).

FTIR analysis

The pellets for FTIR analysis were prepared by mixing foam dried solid with potassium bromide. The spectrums were recorded immediately with care to minimize sample exposure to moisture. The FTIR absorption measurements were recorded in the region 2000–400 cm^-1 at room temperature using a Jasco V530 spectrometer, and analyzed using Origin8^® software (Origin Lab Corporation, USA) [17].

XRPD analysis

The X-ray diffraction analysis is reported for pharmaceuticals to analyse the physical state of mixtures [18]. The XRPD analysis of foam dried products was performed using X-Ray Diffractometer (PW 3710, Philips, Netherlands). Powdered product samples were scanned between 2°–100° 2θ at a scan speed of 0.1° 2θ/sec using 1.524 Å radiations.

DSC analysis

Thermal behaviour of BH foam dried sucrose-phosphate systems was studied to determine the glass transition temperature (T_g) and allow proper design of the process and to investigate their stability by using a DSC (Model 821, Mettler Toledo). Samples (1.5–7mg) were analyzed in crimped, vented aluminum pans under a dry nitrogen purge with an automated liquid nitrogen-cooling accessory [19]. Samples were heated from 25 °C to 250 °C with a scanning rate of 10 °C/min.

Comparative Process Efficiency of EFD and Lyophilization

The optimized composition in EFD with physicochemical characteristics was subjected to lyophilization. For successful lyophilization, the behaviour of the frozen product needs to be characterized prior to freeze drying [19]. The resulting end product should have an acceptable cake structure, good rehydration time, and retention of active viability with sufficient stability at the required temperature. The pre-frozen vials were lyophilized in Labconco (FreeZone 2.5 L, UK) lyophilizer at shelf temperature (–50 °C) lower than obtained from DSC studies as Tg and vacuum (0.014 mBar) for 72 h (condenser temperature –50 °C). The lyophilized systems were protected in similar way as mentioned under EFD. The lyophilized mixtures were analyzed for residual moisture and BH content.

Short-term Storage Stability

The optimized EFD and lyophilized BH products were subjected for short-term stability as per ICH stability testing guidelines for biologicals. Nine vials of the optimized foam dried and lyophilized products were vacuum-sealed and stored at 2–8 °C room temperature and at 40 °C/75% RH for 6 months. Stability products were analyzed at specific time interval. The products in vials were evaluated for appearance, % residual moisture and BH content. The products were reconstituted with Water for Injection IP to determine reconstitution time. The BH content in the products was determined by using RP-HPLC method. The stability products were further characterized by XRPD and DSC.

RESULT AND DISCUSSION:

The focus of the study was to investigate use of sugar-phosphate composite glass to stabilize BH. The effects of stabilizers and their strengths on the physicochemical characteristics of the EFD BH products were studied. Sucrose and trehalose were used as the glass forming materials for their potential stabilizing effects. Phosphates were used to form composite mixtures with sugars to potentiate the stabilizing effects of sugars. As reported in literature, Pluronic F108 and PVP K30 were incorporated to enhance foamability and foam stability, respectively, during processing [20].

Effect of Sugars on foamability and foam stability

Foam, meaning ‘bubbly liquid’, is obtained when a non-equilibrium dispersion of gas bubbles in a relatively small volume of liquid containing surfactants. The properties of surfactant based foams are commonly measured by foamability and foam stability [21]. Pisal et al. studied the effect of sugar on foaming properties of Pluronic polymer [20]. Sugars especially disaccharide are commonly employed as lyoprotectants in lyophilization. In order to further enhance lyoprotective property, sucrose and trehalose were added to surfactant solution to help faster removal of solvent through the foam film. In fact, sugar imparts viscosity to the solution which ultimately helps to improve foam stability over period of time [22]. The comparative foamability and foam stability exhibited by sucrose was superior to the trehalose, Fig. 1.

Estimation of BH

The HPLC method used for analysis of BH showed best resolution at the mobile phase composition of 0.1 % trifluroacetic acid in water: acetonitrile (80:20 v/v) at flow rate 1 mL/min. The BH showed retention time of 2.12 min with high peak resolution at 230 nm and better peak shape. The chromatographic conditions were optimized in order to provide a good performance of the assay.

Effect of pH and Temperature

BH being prone to hydrolysis in solutions, the pH and temperature stability investigations were undertaken. The results revealed that BH solutions undergo least degradation at pH 8.0 (Fig. 2) when stored at low temperatures (Fig. 3) over the period of 4 days.

Figure 2: Effect of varying pH on stability of BH (%) in aqueous solution

Figure 3: Effect of pH on stability of BH in aqueous solution at different temperatures

Effect of Sugars

The protective effect of sugars during drying of thermolabile drugs is based on a narrow balance between the sugar-drug interaction and the glass-forming properties of the sugars [23]. A glass is a liquid state with solid-like properties. In glassy state, molecules are randomly distributed, as in liquid, but the molecular mobility is low, as in solids. This glassy matrix results in molecular immobility of the biomolecule, which gives protection to the dried biomolecule. A good stabilizer during drying should have sufficiently high T_g and provide good interaction with biomolecule [24]. Minimum strength of sucrose at which products were mechanically stable with regular and uniform foam was 20 %w/v, Fig. 4. Products with sucrose strengths 20 %w/v and above showed desired foams. Trehalose at concentration 5 %w/v achieved desire foam height but compare to sucrose at higher concentrations it showed poor foam stability. It is attributed to high viscosity exhibited by trehalose inhibiting removal of water. Trehalose has been reported to be most efficient sugar for preservation of biologicals by freeze drying. Unfortunately, freshly prepared products with low trehalose strengths were stable but during handling and storage foams were collapsed with time.

Figure 4: Effect of sucrose on product feature in concentrations ranging from 5% - 25%.

Effect of PVP

Sugars alone were unable to provide mechanical strength over the time. PVP a plasticizer has high T_gand remain in glassy state at room temperature reported to improve strength of composites [25]. The physical strength of EFD products is enhanced by incorporation of PVP. PVP network in dried state help to reduce foam collapse. Physically, products with sucrose alone were brittle and stable to handling but collapsed during storage. Under this condition water absorption and BH aggregation was increased due to increased surface area. The PVP has been previously reported to increase the T_g of sugar based lyophilized products. It has ability to form three-dimensional network through hydrogen bonding in presence of sugars. This interaction increases mechanical strength and hence stability of dried products. In combination with sucrose PVP at 0.3 %w/v enhanced BH recovery from 74.22±1.23 %w/v to 88.47±0.61 %w/v. The higher residual moisture and low foam height is net result of increased viscosity of the solution. On the contrary, PVP (0.3 %w/v) when used with trehalose BH recovery increased only by 2.35 %w/v and declined by more than 2.2 %w/v with further increments of PVP strength. The product features were appeared to be dependent of PVP concentration.

Effect of Phosphates

The stabilizing effects of sucrose were found synergistic with 0.3 %w/v PVP, so it is of formulation interest to improve their performance further. There is evidence for the modifications of the thermophysical properties of concentrated aqueous trehalose in the presence of sodium chloride and sodium tetraborate [26]. Miller et al. have demonstrated that the combinations of sugars with various ions are superior to the sugars alone as protein stabilizing agents [27]. Such synergism of protective compounds has also been reported using mixtures of trehalose and borate. The ability of this system to protect enzymes [28] and bacteria [29] during freeze-drying has been already reported in literature. Phosphates’ being structurally similar to borates forms glassy composite mixture. Many of the physical properties of sugar-phosphate mixtures have been determined but they have been studied only in the frozen state. Thus, it is of interest to determine effects of phosphate salts on the BH EFD formulations.

Figure 5: Effect of sodium mono phosphate on product features in concentrations ranging from 0.5% - 2.5%w/w.

In the set of mixtures at the optimized sucrose concentration different concentrations of sodium and potassium mono phosphates were incorporated. The effect of sodium mono phosphate (SMP) concentration on sucrose based BH EFD product characteristics are shown in Fig. 5. The SMP as a contributor in sugar glass protectant composite has been reported for preservation of protein structure [30]. It is evident from the observations that the stable foam was obtained in both sucrose mixtures with 1.5 %w/v SMP. Similar effects in stabilization by foam formation has been reported [31].

Comparative Process Efficiency

Lyophilization is widely used process for preservation of sensitive biomolecules. Therefore, the efficiency of EFD was compared with conventional lyophilization for BH stabilization during processing and at storage. In general, the product being lyophilized in a vial collapses at a slightly higher temperature. The effect of variation in collapse temperature is negligible in a system of low solids content because sublimation is very rapid. To determine production parameters for lyophilization, the preliminary collapse temperature was determined from DSC analysis of product composition. The measurements by DSC were conducted using solute concentrations comparable to the concentrations ultimately used in EFD. The lyophilized products were porous pallets with uniform surface morphology. When stored for six months at refrigeration condition EFD products were mechanically stable while lyophilized products were fractured cakes with irregular dense mass due to moisture absorption during storage. The BH recovery by HPLC indicated that efficiency of EFD to retain BH in formulation was superior compared to lyophilized products, Table 4.

Optical Microscopy

Preliminary investigation of the physical state of product contents was performed by optical microscopy. The trehalose and sucrose mixtures were in a glassy state when examined using light microscopy (Motic microscope) indicating absence of crystallinity, Fig. 6. Trehalose and sucrose products with phosphates were non-transparent indicating presence of residual moisture.

Figure 6: Optical microscopy images of sucrose and trehalose products

FTIR Analysis

The FTIR analysis in the region from 4000 to 2000cm⁻¹ was performed to gain an understanding of any possibility of interactions between the formulation components and their effects on the nature of the dried samples. The strength of the sugar-phosphate-PVP interaction through H-bonding in the stabilization of the BH in dried form can be easily interpreted from FTIR spectras. In the present work it was observed that the interaction of sugar/phosphate/PVP with BH occurs via H-bonding between -H/-OH groups of BH and the sugar/phosphate/PVP, respectively, obeying water replacement hypothesis.

XRPD analysis

The physical state of any mixture can be analyzed by x-ray diffraction. The XRPD gives an idea about how much crystallinity is present in a given mixture. In the XRPD patterns of BH EFD formulations comprising only sugars showed the crystalline characteristic peaks 22° and 35° 2θ of trehalose and at 37° 2θ of sucrose. In absence of phosphate/PVP, sugars crystallize out during dehydration drying. For BH-sucrose EFD products, Fig. 7, specific sucrose crystal peaks were observed in XRD patterns at 6°, 8° and 9° 2θ, respectively. These peaks were reduced to certain extent in case of BH-sucrose-PVP EFD products and in BH-sucrose-PVP-SDHP EFD products indicating amorphization. In case of BH based sucrose EFD products the peak intensity was reduced to greater extent than trehalose EFD products. This confirms that the degree of amorphization achieved is more when sucrose is used. It has been reported that crystallization in foam dried products is reduced when inorganic soluble phosphates with PVP were used [32].

Figure 7: Overlain x-ray diffraction patterns(a) pure sucrose (b) Pure trehalose (c) BH product with sucrose (30%w/v) + PVP K30 (0.6%w/v) (d) BH product with sucrose (30%w/v) + PVP K30 (0.6%w/v) + SDHP (1.5%)

DSC analysis

Differential scanning calorimetry (DSC) is frequently used thermal analysis technique that provides detailed information about the physical and energetic properties of substance and mixtures. EFD products containing trehalose and sucrose with the phosphates were crystalline. The observed data conﬁrms that BH with sucrose-SDHP is more likely to be in a glassy state than with trehalose-phosphate combination, Fig. 8. It has been reported that depending on sugar chosen, selection of counter ion (Na or K) can have effect on T_g of the sugar-phosphate mixtures [26]. It is difficult to predict that the changes in T_g as discussed above can be attributed solely to the interaction between sugars and phosphates. EFD BH products containing sugars alone, sugars with PVP K30 and sugars with phosphates did not show endothermic melting within the normal storage temperature range (maximum up to 45°C). Absence of endothermic melting peaks in the endotherm of EFD BH systems within the storage temperature range indicates amorphous nature of product content is evidence of possible positive interaction between them.

Figure 8: DSC thermogram EFD BH sucrose-monobasic phosphate products

Stability study

The objective of the stability study was to evaluate the stability of BH in EFD sucrose-phosphate-PVP composite glass systems. Sucrose renders protection to biomolecules only in the amorphous glassy state [33].

Table 5: Stability data of optimized BH products

Storage Temperature	Period (Days)	Evaporative foam drying
Storage Temperature	Period (Days)	Residual moisture (%w/v)	BH content (%)
4	30	2.94	88.67
	60	3.37	81.01
	90	4.23	78.47
25	30	3.58	92.43
	60	3.91	84.73
	90	4.65	81.33
40	30	4.11	87.50
	60	4.79	71.76
	90	4.98	70.39

The solid state stability of EFD was studied as a function of storage temperature and relative humidity. The high storage temperature conditions were used as an indicator of stabilizing effects of the excipients, which were further confirmed under a more realistic storage condition of 25°C/60%RH, Table 5. Our aim was to define parameters that control the solid state stability in order to rationally optimize the stability of EFD BH. Under experimental storage conditions of 2-8°C and 25°C/60%RH no visual signs of BH degradation were observed. The trend observed for EFD products stored at 2-8°C and 25°C/60%RH was similar but was different for products stored at 40°C/75%RH.

CONCLUSIONS:

Formulation of stable glassy matrix of sugars phosphates composite using PVP is a challenge in the design of EFD products of BH. The Pluronic F108 alone could not produce stable foams. Addition of sugars (30%w/v) improved foam stability. The solution stability of BH was found to be pH dependent. The concentration of sucrose and trehalose required to preserve BH with desired stable foams were 30%w/v and 25%w/v, respectively, but foams in EFD sugar products can be further stabilized with addition of 0.3%w/v of PVP K30. Inorganic water soluble phosphates interact with sucrose and hence forms glassy matrix that protects BH through hydrogen bonding. The moisture has significant effect on the stability of glass and in turn BH. Sugar-phosphate composite glass has capacity to withstand at 25°C/60%RH retaining more than 85% of BH over stability period. As processing stability of BH is dependant of residual moisture, at given circumstances water substitution may be the predominant mechanism governing its stability by glassy matrix formation. Microscopy, FTIR, XRPD and DSC studies reveals suitability of EFD for preservation of BH. Compare to lyophilization, EFD was appeared to be shorter, economic and efficient process. EFD would help manufacturers, distributors, suppliers and hospitals to save money, time and energy. EFD needs some improvements such as elimination of uncontrolled eruptions and spitting of material out of vials or containers during evaporative drying. More parameters must be studied for its comparison with lyophilization and other known and newly developed drying processes. The success of EFD for stable product manufacturing depends on pressure, temperature, container geometry, surface tension and viscosity of sample and bubble nucleation and its growth rate.

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Received on 10.09.2016 Modified on 01.11.2016

Research J. Pharm. and Tech 2016; 9(10):1602-1610.

DOI: 10.5958/0974-360X.2016.00318.8

Composition Codes	Sucrose (%w/v)	Trehalose (%w/v)	PVP (%w/v)	SMP (%w/v)	PMP (%w/v)	PF108 (%w/v)
S1-S6	5 - 30	--	--	--	--	0.6
T1-T6	--	5 - 30	--	--	--	0.6
SP1-SP5	20	--	0.1 - 0.5	--	--	0.6
SD1-SD5	20	--	0.3	0.5 - 2.5	--	0.6
PD1-PD5	20	--	0.3	--	0.5 - 2.5	0.6

Storage period	EFD		Lyophilization
Storage period	Moisture Content (%w/w)	BH content (%w/w)	Moisture Content (%w/w)	BH content (%w/w)
0 day	1.23	92.55	4.91	79.51
Six month	2.37	84.64	5.26	73.47