Clarithromycin Floating Microspheres with Calcium Silicate by Using Emulsion Solvent Diffusion System (ESDS).


Adhikrao V. Yadav1 and Venkat B. Yadav2*

1Krishna Institute of Pharmacy, KIMS University, Karad (MS), India.

2Department of Biopharmaceutics, Government College of Pharmacy, Karad (MS), India.

*Corresponding Author E-mail:



The purpose of the present investigation was to design the multiparticulate floating system to prolong the gastric residence time after oral administration, at a particular site and controlling the release of drug especially useful for achieving controlled plasma level as well as improving bioavailability. Clarithromycin (CTM) is an advanced generation macrolide antibiotic used in treatment of H. pylori and respiratory infection which has a short half-life (3-6 h), low bioavailability (56%) and completely absorbed from GI tract.  With this objective, floating particulate dosage form containing clarithromycin as model drug was designed for the treatment of Helicobacter pylori infection. A controlled release floating microspheres system was designed to achieve increase its residence time in the stomach without contact with the mucosa by emulsion solvent diffusion system (ESDS) containing calcium silicate as porous carrier and Eudragit RS100 as release retardant polymer. Floatable microspheres were developed as a dosage form capable of floating in the stomach. The effects of various formulation and process variables on the particle morphology, in vitro floating behavior, micromeritic properties, drug loading and in vitro drug release were studied. The release rate was determined in 0.1N HCl at 370C.The microspheres were found to be regular in shape and highly porous. The formulation confirmed positive in vitro floating and release characteristics. The drug encapsulation efficiency was also on higher side. Incorporation of Calcium silicate in the microspheres proved to be an effective method to achieve the preferred release behavior through diffusion and buoyancy. The designed particulate system, shows excellent buoyant capability and suitable drug release pattern, could possibly be advantageous in terms of increased clarithromycin effectively against H. pylori.


KEYWORDS: Floating controlled drug delivery system; floating microsphere; Emulsion solvent diffusion method; Methacrylic acid copolymer (Eudragit RS100); Buoyancy, Clarithromycin.



Oral administration is the most flexible, suitable and commonly employed route of drug delivery for systemic action. In fact, for controlled release system oral route of administration has acknowledged the more attention and success because gastrointestinal physiology offers more suppleness in dosage form design than other routes1.Different types of drug delivery systems for oral administration such as drug release rate-controlled delivery systems, time-controlled delivery systems and site-specific delivery systems have been extensively developed. In the cases of rate-controlled and time-controlled delivery systems, sustained drug absorption time is limited to the transit time of the dosage form through the absorption site because, afterward, the released drug is not absorbed.


Therefore, when a drug possesses a narrow ‘absorption window’, design of the sustained release preparation requires both prolongation of gastrointestinal transit of the dosage form and controlled drug release2.


Helicobacter pylori is a widespread human specific pathogen, which is now invented to be the causative bacterium for chronic gastritis, peptic ulcer and adenocarcinoma, one of the most common forms of cancer in humans and its elimination requires high concentration of drug within the gastric mucosa for extended duration. Thus, floating oral delivery system is expected to remain buoyant in a lasting way upon the gastric contents and enhance bioavailability of all drugs which are well absorbed from the GI tract. One or two antibiotics combined with a proton pump inhibitor are proved effective in clinical application. Yet, some other reports and clinical trials indicate that the therapies cannot bring out complete suppression of H. pylori and recommend that the therapeutic effect needs more investigation3-4. There are two major reasons for the collapse of H. pylori eradication with conventional dosage forms of antibiotics. One of the reasons for incomplete eradication may be the degradation of antimicrobial agents such as amoxicillin and clarithromycin by gastric acid. Thus, the administration of high doses of antimicrobial agents on a daily basis is necessary for H. pylori eradication, but they are usually accompanied by adverse effects and poor patient compliance. Another reason for incomplete eradication is probably that the residence time of antimicrobial agents in the stomach is so short that effective antimicrobial concentrations cannot be achieved in the gastric mucous layer or epithelial cell surfaces where H. pylori exists 5-6.


Several approaches have been developed including gastrointestinal targeting dosage forms 7, intragastric floating systems8-9, high density systems10, mucoadhesive systems adhering to the gastric mucosal surface to extend gastric residence time11, magnetic systems12, unfoldable extendible or swellable systems13 and superporous hydrogel systems 14 in order to prolong the residence time of dosage forms in the stomach. One technique involves the preparation of a device that remains buoyant in stomach contents due to a density lower than that of the gastric fluids15-16. An intragastric flotation system can prolong gastric residence time (GRT) of dosage forms, resulting in better drug absorption at the proximal small intestine as well as in the stomach. Extension of GRT can also provide sustained pharmacological action. A hydrodynamically balanced system (HBS) 17 was initially described as a flotation device exhibiting a density lower than that of water. A disadvantage of this system is the high variability of gastrointestinal transit time, attributable to its all-or-nothing emptying process. Therefore, a multiple-unit flotation system that can be distributed widely throughout the gastrointestinal tract, affording the possibility of longer lasting and more reliable release of drugs, has been sought.


Murata et al.18 prepared alginate gel beads which on oral administration; they are having ability to float on gastric juice. When alginate gel beads containing chitosan were administrated orally to guinea pigs, the beads were floated on the gastric juice and released the drug in the stomach. This method has been widely employed to prevent repetition of peptic ulcer disease, an incident that is associated to infection caused by Helicobacter pylori19. Iannuccelli et al.20 reported air-included multiple-unit compartment system showed excellent buoyancy in vitro and prolonged GRT relative to the controls in vivo under fed state. However, in the fasted state, intragastric buoyancy of the devices did not influence GRT. Furthermore; Kawashima et al.21-23 developed hollow microspheres (microballoons) in order to prolong GRT of the dosage form. This gastrointestinal transit-controlled preparation is designed to float on gastric juice with a specific density of less than 1.Clarithromycin is a macrolide, orally absorbed, broad-spectrum antibiotic. It is widely used in a standard eradication treatment of gastric H. pylori infection combined with a second antibiotic and an acid-suppressing agent. Clarithromycin has highest rate of eradication of H. pylori in monotherapy in vivo, though it is unstable and rapidly undergoes degradation in low pH of gastric acid.24


The objective of the present investigation was to evaluate gastro-retentive performance of the optimized floating microsphere consisting calcium silicate (CS) as porous carrier; clarithromycin (CTM), as macrolide antibiotics; and Eudragit RS100 as polymer, which is capable of floating on gastric fluid and delivering the CTM over an extended period of time. The CS, has a characteristically porous structure with many pores and a large pore volume, has a sustained release property and has been used as an industrial liquid absorber or a compressive adjuvant of powder. It has floating ability due to the air trapped within its pores when covered with a polymer. Clarithromycin (CTM) is an advanced generation macrolide antibiotic used in treatment of H. pylori and respiratory infection which has a short half-life (3-6 h), low bioavailability (56%) and completely absorbed from GI tract. Thus the CTM possesses all the characteristics required to develop a floating controlled release system with increased GRT, hence was chosen as the drug candidate for the present research work25-26.The goal of the current investigation was to assess the usefulness of intragastric buoyant properties of multiparticulate floating microsphere of clarithromycin by the emulsion solvent diffusion method. The efficiency of drug entrapment into microsphere and the buoyancy properties of the same along with their release profile were also investigated.




Clarithromycin was generously supplied as a gift sample by Alembic research center (Vadodara, India). Eudragit RS100 was obtained as a gift sample from Degussa India Pvt. Ltd. Research Center, Mumbai, India. Calcium silicates, polyvinyl alcohol (PVA), Tween 80 were procured from Loba-Chemie Industrial Co. (Mumbai, India). Ethanol, dichloromethane and other solvents were purchased from S. D. Fine (Mumbai, India).



Preparation of CTM adsorbed Calcium silicate:

The porous carrier Calcium silicate (CS) was added into 10 ml ethanol solution of CTM (3gm). This solution was sonicated (Soniweld, Imeco Ultrasonics, India) to absorb the drug solution inside the pores of porous carrier, while removing the air. The excess ethanolic solution was removed by filtration and dried in vacuum, which produced drug adsorbed porous carrier.


Preparation of floating microspheres:

Microspheres were prepared using a modified emulsion solvent diffusion system. In brief, the CTM absorbed CS was added into the polymer solution of Eudragit RS100 in ethanol and dichloromethane (2:1) and sonicated using probe sonicator. The resulting suspension was poured into 200 ml aqueous solution of PVA (0.75% w/v) at 400C. The formed emulsion was stirred at 500 rpm for 3 hrs employing a propeller type agitator. The microspheres were separated by filtration, washed with water and dried at room temperature in desiccators for 24 hrs. The microspheres of CTM without Calcium silicate were also prepared using same method for comparative study. The effect of process variables like polymer concentration, stirring rate, temperature, amount of porous carrier and concentration of aqueous phase on the particle size, buoyancy, drug entrapment efficiency and drug release were studied (Table:1 and 2).


Table: 1 Impact of Process variables on size and appearance of floating microspheres.

Sr. No.

Name of variable

Size (µm)



Amount of Polymer(gm)



Irregular spheres with some pores



Spheres with pores



Ideal spheres with large number of spheres


Temperature of the preparation(0C)



Spherical particles with maximum pores



Spherical particles with minor pores



Large agglomerates without pores


Volume of aqueous phase(mL)



Spherical particles



Irregular particle



Irregular and road shaped particles


Table: 2 Product code for floating microsphere with optimized process variables at different amounts of carriers (calcium silicate)

Sr. No

Product Code

Ethanol: DCM ratio (mL)

Eudragit RS100 (gm)

Calcium silicate content (gm)






















Entrapment efficiency of Clarithromycin and production yield:

In a volumetric flask, 10 mg of accurately weighed clarithromycin loaded microsphere was added and dissolved in 3 ml of dichloromethane following dilution with 100 ml of 0.1N hydrochloric acid, stopper the flask and sonicate for 2 hrs on sonicator. Eudragit S and the Calcium silicate powder did not interfere under these conditions. Take 10 mL of above filtrate solution and diluted to 60mL with 0.1N HCl, adjust the pH 6 to 7 by adding 0.4M NaOH solution and make up the volume up to 100mL with distilled water. Take 1mL form the above solution diluted to 6 mL with the distilled water in 10 mL volumetric flask  to it add 1.2mL Eosin Y solution (4 X 10-3 M)  mix then well to it add 1 mL 0.4M acetate buffer (pH 3) adjust the volume up to 10mL with distilled water. The absorbance was measured spectrophotometrically at 545nm against an appropriate blank prepared simultaneously. Each determination was made in triplicate. The percentage drug entrapment and yield were calculated as follows


Floating behavior/Buoyancy study:

Fifty milligrams of the floating microspheres were placed in simulated gastric fluid (pH 2.0, 100 mL) containing 0.02 w/v% Tween 80. The mixture was stirred at 100 rpm in a magnetic stirrer. After 1, 2, 3, and 4 hrs, the layer of buoyant particles was pipetted; subsequently, the floating particles were separated by filtration. Particles in the sinking particulate layer were separated by filtration. Both types of particles were dried at 400C overnight. Weights were measured and buoyancy was determined by the weight ratio of the floating particles to the sum of floating and sinking particles.



               Buoyancy % = ----------------- X 100

                                             Ws + Wf


Where Wf and Ws are the weights of the floating and settled microparticles, respectively. All the determinations were made in triplicate.


Micromeritic properties:

Flow properties of the drug and prepared melt granules were studied by determining the bulk density (σb), tap density (σt), Carr’s Index and Hausner ratio. A weighed quantity of the samples was taken to determine the bulk and tap density. The properties were determined using following equations.


Bulk density (σb) = Mass / Poured volume                       (1)

Tap density (σt) = Mass / Tapped volume                         (2)

Carr’s Index = [(σt – σb) / σt] x 100                                  (3)

Hausner ratio = (σt / (σb)                                                   (4)


True density was determined using a benzene displacement method. Porosity [20] (ε) was calculated using the equation:


Porosity (ε) = (1-Pp/ Pt) X 100


Where Pt and Pp are the true density and tapped density, respectively.

Angle of repose θ of the microspheres, which measures the resistance to particle flow, was determined by a fixed funnel method [21] and calculated as


Tan θ= 2 H/D


Where, 2H/D is the surface area of the free standing height of the microspheres heap that is formed on a graph paper after making the microspheres flow from the glass funnel.


Measurement of in vitro drug release:

The in vitro release study for all the formulations were carried out by USP Dissolution Test Apparatus Type-II (paddle). The temperature of the dissolution medium (0.1 M HCl, 900 mL) was maintained at 370C ± 10C with a stirring rate of 50 rpm. This study was done for 8 hrs. The microspheres were placed inside the dissolution vessel. At time of 1, 2, 4, 6 and 8 hours, 10 mL samples were withdrawn. The volume of dissolution fluid was adjusted every time to 900 mL by adding fresh 10 mL dissolution medium to maintain sink condition. Samples were suitably diluted with 2 mL Folin-Ciocalteuís phenol reagent (diluted to 1:2 with distilled water) and 2 mL of 20% sodium carbonate solution and 0.1 M HCl up to 10 mL and assayed spectrophotometrically at λ=760 nm in a double beam UV and visible spectrophotometer (Shimadzu UV 1700) against reagent blank. The drug concentration was calculated using standard calibration curve.


Mechanism of release:

The mechanism of release was determined by fitting the release data to the various kinetic equations such as zero-order, first-order, Higuchi, and Korsmeyer-Peppas and finding the R2 values of the release profile corresponding to each model.


Surface morphology:

Surface morphology of the microspheres was examined by scanning electron microscopy in a Hitachi instrument (Model S-2400, Japan) after vacuum sputtering the particles with gold.


Fourier transforms infrared spectroscopy (FTIR):

FT-IR spectra of prepared microspheres were recorded on Shimadzu FT IR – 8400 spectrophotometer (Shimadzu Corporation, Kyoto, Japan). Potassium bromide pellet method was employed and background spectrum was collected under identical situation. Each spectrum was derived from single average scans collected in the region 600 – 4000 cm-1 at spectral resolution of 2 cm-2 and ratio against background interferogram. Spectra were analyzed by software supplied by Shimadzu.


Differential Scanning Calorimentry (DSC):

Thermal properties of the untreated drug and the prepared microspheres were analyzed by DSC (TA Instruments, USA, and Model: SDT 2960). The samples were heated in a hermetically sealed aluminum pans. Heat runs for each sample were set from 30 to 2500C at a heating rate of 10 0C/ min, using nitrogen as blanket gas.


X-ray powder diffraction (XRPD) studies:

The XRPD patterns of the prepared microspheres were monitored with an x-ray diffractometer (Philips PW 1729, Analytical XRD, Holland) using Ni filtered CuK (α) radiation (intensity ratio (α1/ α2): 0.500), voltage of 40 KV, current of 30 mA and receiving slit of 0.2 inches. The samples were analyzed over 2q range of 5.010-39.990o with scanning step size of 0.0200 (2θ) and scan step time of one second. To minimize the effect of particle size on preferred orientation, all the samples were first passed through sieve no. 120 (125μm) and collected on sieve no. 240 (62.5μm).


Statistical analysis:

Differences in in vitro drug release of clarithromycin from calcium silicate based microspheres were statistically analysed by one way analysis of variance (ANOVA) with post test (Dunnett’s multiple comparison tests). Statistically significant differences between in vitro drug releases of formulations were defined as p < 0.05. Calculations were performed with the GraphPad-Instat. Software Program (GraphPad-Instat Software Inc., San Diego).



The floating microspheres were prepared by emulsion solvent diffusion system. A solution or suspension of Eudragit RS100 with calcium silicate in ethanol and dichloromethane was poured into an agitated aqueous solution of polyvinyl alcohol. The ethanol rapidly partitioned into the outer aqueous phase and the polymer precipitated around dichloromethane droplets. The successive evaporation of the entrapped dichloromethane led to the formation of internal cavities within the microparticles. The incorporation of drug adsorbed calcium silicate into the formulation may produce porous structure within the microspheres. The sonication produced drug adsorbed calcium silicate in fine state of subdivision.


A fraction of the polymer solution aggregated in a fibre like structure, since it solidified prior to forming droplets or the transient droplets were broken before the solidification was complete. When ethanol quickly diffused out of the organic phase (polymer solution) into the aqueous phase, Eudragit RS100 dissolved in ethanol solidified in fibre like aggregates. It is documented that when the diffusion rate of solvent out of emulsion droplet was too slow, microspheres coalesced together. Converse conversely, when the diffusion rate of solvent is too fast, the solvent may diffuse into the aqueous phase before stable emulsion droplets are developed, causing the aggregation of embryonic microsphere droplets.


Impact of external aqueous phase:

A potential advantage of using large volumes of the external aqueous phase are the reduction of the required stirring times. The solubility of dichloromethane in water is 1% w/v. Using larger volume (400 to 500 mL), the diffusion of dichloromethane into the aqueous phase and hence solidification of particles occurred faster as compared to 200 mL. Thus particles could be separated after shorter stirring times. It was found that a saturated solution of polymer produced smooth and high yield microspheres. The undissolved polymer produced irregular and rod shaped particles.


Impact of temperature:

Preparation at 20 or 300C provided porous microspheres having higher porosity with a surface so rough as to crumble upon touching. At 400C, polymer and the drug were co-precipitated and the shell was formed by the diffusion of ethanol into the aqueous solution and simultaneous evaporation of dichloromethane. In contrast, microspheres prepared at 500C demonstrated a single large depression at the surface, which was a consequence of rapid evaporation of dichloromethane.


Impact of polymer quantity:

When the amount of Eudragit RS was 1.5 g in 15 mL of organic phase, it started to form aggregates. When the amount of Eudragit RS100 was less than 0.5 g in 15 mL of organic phase, it started to form irregular microspheres with some pores.


Impact of solvent ratio:

The ratio of dichloromethane with ethanol also affected the morphology of the microspheres and the best result with a spherical shape was obtained when the ratio of ethanol to dichloromethane was 2: 1. But the average particle size increased and the wall thickness also increased as the amount of Eudragit RS100 increased.


Impact of Stirring rate:

It is obvious that the rotation speed of the propeller affects the yield and size distribution of microspheres. As the rotation speed of the propeller increased from 250 to 1000 rpm, the average particle size decreased (figure 1, table 3), while maintaining its morphology. The optimum rotation speed for this experimental system was 500 rpm, as judged from the results of particle size and size distribution, and drug content.


Figure: 1 Impact of stirring rate and amount of bridging liquid on Particle size.


Table: 3 Impact of stirring rate and amount of bridging liquid on Particle size.


Variable X1:

Amount of DCM(mL)

Variable X2: Speed of agitation(rpm)

Particle size(µm)


1 (-1)*

500 (-1)



2 (0)

500 (-1)



3 (+1)

500 (-1)



1 (-1)

1000 (0)



2 (0)

1000 (0)



3 (+1)

1000 (0)



1 (-1)

1500 (+1)



2 (0)

1500 (+1)



3 (+1)

1500 (+1)


*Values in parenthesis indicate coded level

Entrapment efficiency of Clarithromycin and production yield:

The percent drug entrapment in all the microsphere formulations was found to be good (above 80%) at all levels of drug loading. The high entrapment efficiency of CTM is supposed to be due to its poor aqueous solubility. The extent of loading influenced the particle size distribution of microspheres. When the loading was high, the proportion of larger particles formed was also high. With 90% entrapment, most of the particles were in the size range of 250–300 µm, suitable for oral administration. The size of the microspheres formed may however be a function of many factors such as stirring speed, viscosity of the dispersed phase and dispersion medium, temperature, amount and size of porous carrier, etc. Therefore, it is possible to prepare microspheres of desired size by varying some of these parameters.


Flowability parameters:

According to the literature, powders with a Compressibility Index (CI) between 5 to 15%, Hausner ratio below 1.25 and angle of repose below 30 shows good flowability suitable for directly compressible tablets. The prepared microspheres (Table 4) possess a CI between 13 and 17%, Hausner ratio was below 1.20 and angle of repose were below 22. The rheological properties of prepared microspheres revealed a good flowability because of their spherical size which reduces the surface area and increases flow rate.


Floating behavior:

The floating test was carried out to investigate the floatability of the prepared microspheres. The floating capacity differed according to the formulation tested and the medium used. The microspheres were spread over the surface of SGF and the fraction of microspheres settled down as a function of time was quantitated. All the high calcium silicate based formulations (Fig: 2) showed good floating ability (around 80%). More than 80% of the particles kept floating for at least 4 h. The good buoyancy behavior of the microspheres may be attributed to the hollow nature of the microspheres.Tween 80 (0.02% w/v) was added in SGF, counteracted the downward pulling at the liquid surface by lowering surface tension, because the relatively high surface tension of simulated gastric fluid causes the highest decrease of surface area at the air fluid interface. It was also observed that the microspheres of larger size, showed the longer floating time.


Figure: 2 Buoyancy studies of CTM and prepared microspheres.


Figure: 3 SEM of Clarithromycin floating microspheres with and without calcium silicate.


Table: 4 Evaluation parameters of clarithromycin floating microspheres.

Sr. No.

Evaluation parameter*

Product code






% Drug entrapment

82 ± 2.36

87 ± 1.85

90 ± 1.55

92 ± 2.50


% yield

85 ± 2.56

90 ± 1.56

92 ± 1.35

93 ± 1.63


Mean particle size (µm)

90 ±1.25

180 ±2.15

170 ±2.68

190 ±1.95


Bulk  density (g/cm3)






Tapped density (g/cm3)






True density(g/cm3)

0.856 ±0.15

1.086 ±0.12

1.056 ±0.10

1.017 ±0.16



20.56 ±1.23

36.92 ±2.35

36.07 ±2.30

34.61 ±2.85


Compressibility index (%)

16.91 ±0.89

13.86 ±0.76

14.07 ±0.87

16.54 ±0.57


Hausner’s ratio

1.20 ±0.08

1.16 ±0.05

1.16 ±0.07

1.19 ±0.05


Angle of repose





* Each value represents mean ± S.D. (n = 3)


Morphology by SEM:

Calcium silicate based Eudragit microspheres were mostly sphere-shaped in appearance; still some were found to be elongated. The porous nature of the Calcium silicate and spherical shape of the microspheres are clear from their SEM photomicrographs (Fig.3). In SEM, there are many pores and cavities in the microspheres containing calcium silicate.


In vitro drug release study:

The effect of Calcium silicate content on in vitro drug release from prepared microsphere was shown in (Fig: 4).Release of CTM from calcium silicate based microspheres was evaluated in 0.1 M HCl.There was nonsignificant effect of increase calcium silicate in prepared microspheres on the dissolution rate. About 75-85% CDR in 8 hrs for both microspheres with and without calcium silicate.


Figure: 4 In vitro release profile of CTM and prepared microspheres.

In order to investigate the mode of drug release from floating in prepared microspheres the release data were analyzed with the following mathematical models: zero-order kinetic, first-order kinetic, Higuchi equation, Hixon Crowell, and Corse Mayer Pappas (Table:5). The R2 values of Higuchi Plot release as well as R2 values of zero order release pattern for all prepared microspheres were near one comparative to First Order, Hixon Crowell, and Corse Mayer Pappas. The examination of the coefficient of determination (r2) indicated the drug release followed diffusion controlled mechanism from the microspheres, as the r2 values for Higuchi's square root of time (ranged from 0.974 to 0.984) were always higher in comparison to zero (ranged from 0.969 to 0.994).Therefore, the most possible mechanism that the release patterns of all formulations followed was non-fickian diffusion or anomalous diffusion. There was no burst effect from any of these formulations.


Table: 5 R2 values of different in vitro dissolution release mechanism models of prepared microspheres

Product Code

R2 valve

Zero Order

First Order

Hixon Crowell

Corse Mayer Pappas

Higuchi Plot

































FTIR Study:

The principal peaks of the clarithromycin includes 1734, 1692, 1108, 1170, 1052cm-1.FT-IR spectra were measured in order to establish the molecular state in CTM and optimized agglomerated crystals (Fig: 5).CTM crystals show characteristic peaks of C=O stretching vibration from ketone group in a lactone ring (at 1689.17 cm−1) and from O-C=O stretching vibration in a lactone ring (at 1732.13 cm−1). The all principal peaks of clarithromycin were observed in the prepared microsphere. This indicated that there was no difference between the internal structures and conformation of these samples at the molecular level.



Figure: 5 FTIR spectra of Clarithromycin and their floating microspheres with and without calcium silicate.

X-ray diffraction study:

The powder X-ray diffraction patterns of floating microspheres obtained by  emulsion solvent diffusion system are shown in (Fig:6).It was found that the intensities of X-ray diffraction peaks decreased in floating microspheres compared to CTM which indicated that the clarithromycin in microspheres are converted into crystalline form.


Figure: 6 Powder X-ray diffraction patterns of Clarithromycin and their floating microspheres with and without calcium silicate.


DSC Study:

The endothermic peak (Fig: 7) due to fusion was observed at 2260C indicating its melting point. From the DSC spectra, the broad exothermic peaks occurring in the range from 80 to 1250C and the exothermic peak occurring in the range from 110 to 1300C were considered to be due to a recrystallization process. There is slightly decrease in melting point for prepared melting point may be due to interaction of CTM with used polymers and excipients.


Figure: 7 DSC curves of Clarithromycin and their floating microspheres with and without calcium silicate.


Floatable microspheres with acrylic polymers such as Eudragit RS100 and porous structure carrier calcium silicate were successfully prepared by the emulsion solvent diffusion system. The prepared microspheres were easily floating in SGF containing Tween 20 (0.02% w/v) solution. Integration of CS in the microspheres proved to be a valuable method to achieve the desired release behavior and buoyancy. The designed particulate microsphere systems, combining excellent buoyant ability and suitable drug release pattern. The developed floating microspheres of clarithromycin are found to be safer and more effective which the need of day is in pharmaceutical industry as an alternative drug delivery system. The microspheres could be compressed into tablets, filled into capsules as unit oral solid dosage form.



The authors wish to thank Alembic Research Center (ARC), Vadodara Gujarat (India) for providing clarithromycin as a gift for this research work. The authors are grateful to Shivaji University, Kolhapur, Maharashtra, India for providing differential scanning calorimetry, infrared spectroscopy and powder X-ray diffractometry facilities, and to the Principal of the Govt. College of Pharmacy, Karad, Maharashtra, India for providing laboratory facilities and regular encouragement.



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Received on 05.01.2010       Modified on 07.03.2010

Accepted on 13.04.2010      © RJPT All right reserved

Research J. Pharm. and Tech.3 (3): July-Sept. 2010; Page 784-791