The drug release profile from the calcium pectinate beads was carried out using the USP type II
dissolution test apparatus using 900 ml 0.1 N HCL maintained at 37
0.5 C and stirred at 50
rpm. Sample were collected periodically and replaced with fresh dissolution medium to maintain
sink condition. Drug release was determined using UV spectrophotometer at 277 nm. Data
analysis was done using PCP Disso software (Version 2, developed by BVDU's College of
The formulation meeting the set objective was selected after screening the results of all
evaluation parameters for the developed formulations . The surfacemorphology of the optimized drug loaded calcium pectinate beads was carried out using
scanning electron microscope (SEM). The cross sections of randomly selected beads from
optimized batch were coated with gold to a thickness of about 30 nm in vacuum evaporator.
Morphological examination of the surface, external and internal structure of the dried beads was
then carried out. The SEM images for the optimized formulation have been depicted in Figure 1.
Figure 1: Scanning Electron Microscopy (SEM) images
Stability Study for Optimized Formulation
The stability study for the optimized formulation was carried out as per ICH guidelines by
keeping formulated beads at, 40
2 0C/ 75 %RH for the period of three months. The evaluation
was performed for physico-chemical parameter like drug contain, floating time and in vitro drug
release at day 0, 30, 60 and 90.
Result and Discussion
Thus been considerable research over the last decade on the possibility of controlled and
site-specific delivery to the GIT by controlling the GI transit of orally administered dosage
forms. Numerous polysaccharides have been tried as an excipient into pharmaceuticals due to
their biocompatible, biodegradable, inexpensive and non-toxic nature. These materials undergoes
simple ionotropic gelation to form multiparticulate system which can provide various desired
drug release patterns. In low-density approach, the spherical beads apparently having lower
density than that of gastric fluid can be used as a carrier for controlling the release of a drug in
the upper part of the GIT.
Drug - Excipients Compatibility Study
Physical mixtures of the drug and LMP that were placed at 55 C in dry and 75 %RH
environment were observed for caking, discoloration, liquefaction and other physical changes
after 15 days. It was observed that there was no caking, discoloration and liquefaction. The
presence of any physical incompatibility would have led to caking, discoloration and liquefaction
and in absence of that it can be concluded that the drug and polymer were compatible with each
The physicochemical interaction between drug and polymer was confirmed by using FTIR
spectroscopy. IR Spectra of physical mixture of the drug and LMP before keeping it for
compatibility study were recorded. Spectra of the physical mixture showed all characteristic
peaks of the drug as well as the LMP intact. Hence it can be said that there is no interaction
between drug and LMP. DSC is one of the tools to investigate the possible physical and chemical
interaction between drug and polymer.DSC spectra of metronidazole shows sharp endothermic
peak at 160.10 C that corresponds to the melting point of the drug which confirms the purity of
metronidazole. DSC Spectra of physical mixture of the drug and LMP before compatibility study
revealed thermal transition at 253.00 C which corresponds to the melting point of the LMP and
sharp endothermic peak at 158.20 C corresponding to the melting point of the drug. The values
were congruent with the melting point of the drug and polymer confirming the compatibility
between drug and the polymer.
Beads Size and Shape
Size and shape was determined by using optical microscopic method. The oil concentration and
polymer concentration is an important parameter which affected the size and shape of the beads.When the concentration of the oil was increased in the formulation the size of the beads was also
found to be increased. Formulation F1 containing 10 %v/v oil exhibited average beads size
0.06 mm and batch F4 containing 40 %v/v oil having beads size of 2.22
Polymer concentration also affected the size and shape of the beads. It was observed that as the
LMP concentration goes below 3%w/v then beads became elongated whereas for more than 4
%w/v concentration, beads shape was changed from spherical to disc like and irregular. Beads of
formulation F5 to F8 (4 %w/v polymer) were spherical and size was larger than formulation F1
to F4 (3 %w/v polymer).
The floating behavior of all the beads was studied using USP dissolution apparatus type II
(Electrolab TDT 08L). The oil containing calcium pectinate beads floats immediately and
remained buoyant for more than 12 hrs. However the amount of oil used in the formulation has a
significant impact on the buoyancy of the formulations as concentration of oil below 10%w/w
did not exhibit any floating. The different floating lag time was observed for formulation F1-F8
due to varying oil concentration. Floating lag time was found to decrease with increasing the oil
concentration in formulation. Batches F1 to F4 having varying oil concentration exhibited
different floating lag time.
Batch F1&F9 (10% oil) has a floating lag time 12-13 minutes, batch F2& F10 (20% oil) has
floating lag time 5-6 minutes, batch F3& F11 (30% oil) has floating lag time 2-3 minutes
whereas formulation F4& F12 containing (40% oil) has floating time 10-20 second. The floating
behavior of the Helianthus annuus pectin beads was similar to that of Passiflora edulis
flavicarpa pectin beads. Hence it can be said that the type of pectin and degree of esterification
did not affect the buoyancy behavior of beads.
Swelling properties were studied by measuring the % water uptake after 2 hrs in 0.1 N HCL (1.2
pH) maintained at physiological temperature of 37 0C. The maximum % swelling was observed
within 20-40 min followed by sudden reduction in weight in the next 20- 30 min. This effect
might be due to the solubility of drug and polymer that could have influenced the swelling
behavior of the beads. Batches having low concentration of polymer (less than3%) exhibitedfaster erosion due to weak gel strength. Batches prepared using high polymer concentration
(more than 4%) showed maximum swelling ratio and swelling index and no erosion till 120 min.
Cross linking agent concentration also had significant impact on the swelling as it was observed
that high amount of cross linker exhibited less erosion of beads. Curing time is also one of the
major factors affecting swelling ratio and swelling index. Curing time less than 15 min showed
faster erosion of beads with minimum swelling ratio and swelling index due to incomplete crosslinking of pectin in the formulation. The source of LMP did not exhibit any influence on
swelling behavior as beads obtained from pectin of both seeds showed similar swelling.
Drug Content and Drug Entrapment Efficiency
Drug content and drug entrapment efficiency of formulated oil-entrapped calcium pectinate
beads containing metronidazole ranged from 75.94
1.16 to 92.06
2.08 and 75.90
2.02 respectively. It was found that drug content and entrapment efficiency of oil
entrapped calcium pectinate beads was increased with increase in oil concentration. The
phenomenon of increasing drug content and entrapment efficiency may be due to either
partitioning of some amount of drug in the oil phase or formation of oil barrier that could have
obstructed the passage of molecule to external media during preparation.
The concentration of the polymer also had influence on the drug content and entrapment
efficiency. The increased in polymer concentration resulted in the increase in the drug content
and entrapment efficiency. This could have happened due to increased viscosity of the emulsion
which might have prevented drug leaching into the cross linking solution. This means increased
in polymer ratio in the formulation has helped in higher drug entrapment. Results of this study
have been depicted in table 3 and 4.Curing time is also one of factors that affected the drug
content and drug entrapment efficiency. With increasing the cross-linking (curing) time increase
in the % drug entrapment efficiency of calcium pectinate beads was observed.
Table 3: Characterization of ﬂoating beads of metronidazole from batches F1 to F8
Table 4: Characterization of ﬂoating beads of metronidazole from batches F9 to F16
In Vitro Drug Release
In vitro drug release study to examine the suitability of the calcium pectinate beads as a
gastroretentive drug delivery system was performed in 0.1 N HCL (simulated gastric fluid
pH1.2) using USP type II dissolution apparatus. Formulations prepared from two different
polymers (LMP) with varying concentration showed the different release patterns. Formulations
F1 to F4 having polymer concentration 3 %w/v exhibited the release up to 10 hrs. Formulations
F5 to F8 having polymer concentration 4 %w/v could prolong the release upto12 hrs. Thus it can be said that increase in polymer concentration resulted in control over the drug release. This
release profile could have been due to the higher concentration of pectin in beads resulted in
more hydrophilic property to beads that could binds better with aqueous medium to form viscous
gel structure and which may block pore on the surface of beads.
The significant increase in drug release from the pectin beads containing metronidazole was
observed with increasing oil to water ratio. The mechanism involved into slow and sustained
drug release from pectinate floating beads containing high amount of entrapped oil must be the
saturation of the drug. Actually, drug transportation from beads to the dissolution medium may
undergo two steps. 1) The drug may diffuse out of oil pockets into bead-matrix. 2) It may diffuse
out of the matrix into the dissolution medium. However in beads with high concentration of oil
most of the drug remained saturated and dispersed in the oil pockets of the beads to from a drugoil dispersed matrix. The beads obtained from Helianthus annuus pectin exhibited better control
over the drug release than the LMP obtained from Passiflora edulis flavicarpa although not very
Figure 2: Drug release profile for batch F1 to F8 (Helianthus annuus pectin)
Figure 3: Drug release profile for batch F9 to F10 (Passiﬂora edulis ﬂavicarpa pectin)
Selection and Morphological Examination of the Optimized Formulation
Formulation F7 prepared from Helianthus annuus pectin was selected as optimized formulation
based on the results of the physicochemical evaluation. Morphological examination of the
optimized formulation beads was carried out using scanning electron microscope. Upon air
drying, the optimized calcium pectinate beads became small, dense and flattened with wrinkled
circumferences due to water diffusing gradually from the sphere under drying process. [15
]. The oil entrapped calcium pectinate beads were more spherical
without hollowness in the middle. The oil entrapped calcium pectinate beads were like a sponge.
The pores on the surface of beads represented the oil droplets and their size influenced by the
concentration of the oil. Figure 1 shows the internal and external morphology of oil entrapped
calcium pectinate beads containing 30% sunflower oil. The surface of oil entrapped calcium
pectinate beads showed small pores of around 10-40
m containing oil droplets dispersed all
over the surface. The pore size was observed to be small due to the homogenous dispersion of
the small fraction of oil phase in pectin solution.
The accelerated stability study was conducted onto the optimized formulation for three month.
The visual observation showed that there was no change in physico-chemical properties of ormulation as well as no change in the floating time at the end of three months. The results of
stability study are depicted in table no.5. Value of drug content shows no significant changes
during time of stability study thus it can be suggested that said formulation was stable. In vitro
drug release also does not have any significant changes in drug release pattern at the day 0, 30,
60 and 90 days and follows peppas model for drug release.
Table 5: Evaluation of stability study
The use of naturally occurring polysaccharides functioning as biopolymers has increased in the
area of novel sustained release formulation [16
].These biopolymers are having a
unique nature of forming hydrogel beads when they are cross linked with suitable polyvalent
cations. These polyanions gained more importance in the development of biocompatible novel
sustained and targeted drug delivery product as they are capable to encapsulate large number of
micro and macro therapeutic molecules in their hydrogel meshwork structure.
We made an attempt to evaluate LMP obtained from two different sources-seeds of Helianthus
annuus and seeds of Passiflora edulis flavicarpa. The floating beads formulation containing
metronidazole using LMP for sustained gastroretentive delivery was successfully developed. The
developed pectinate beads had excellent drug entrapment efficiency, appropriate floating ability
in gastric fluid with a minimum floating lag-time, suitable controlled release pattern. There was
no significant variation in the properties and behavior of beads prepared using LMP from two
different sources. Optimized formulation showed good stability over 90 days with respect to drug
content, floating lag time and drug release.
Authors would like to special thanks Abott laboratories for gift sample of Metronidazole,
Krishna pectin, Jalgaon for gift sample of pectin and SNJB's SSDJ College of pharmacy
(Chandwad), for their kind support.