The aim of this study was to develop a novel HPMCP capsule. The HPMCP capsule containing99mTc-DTPA and lactose was evaluated in in vitro and in vivo studies. First of all, the HPMCP capsules were prepared and characterized with lenght and diameter size, brittleness facility, moisture content and microbiological test. In vitro resistance and solubility studies of prepared capsules were tested at pH 1.2 and pH 7.4 buffers. The radiolabeled HPMCP capsules were administrated to fasted volunteers. The disintegration times and positions of capsules were recorded by using gamma scintigraphy. In vitro studies showed that HPMCP capsules were gastro resistant for 2 h at pH 1.2 and dissolved at pH 7.4 in 20-25 minutes. The radiolabeled capsules did not disintegrate in stomach whereas disintegrated in intestines. In conclusion, it was found that, the prepared HPMCP capsules can be an alternative to the hard gelatine capsules and used for intestinal targeting.Keywords: Capsule, hydroxypropylmethylcellulose phthalate (HPMCP), gamma scintigraphy, radiolabelling, technetium-99m

Asikoglu, M.

Cetin, E.O.

Gundogdu, E.

Kirilmaz, L.

Orumlu, O.

English

International Journal of Drug Delivery

International Journal of Drug Delivery 3 (2011) 279-285 
http://www.arjournals.org/index.php/ijdd 
 
Original Research Article 
                                                            
ISSN: 0975-0215 
In Vitro and In Vivo evaluation of hydroxypropylmethyl cellulose phthalate 
capsules 
E.O. Cetin1, M. Asikoglu2, E. Gundogdu1, O. Orumlu2, L. Kirilmaz1 
 
 
*Corresponding author: 
 
E.O. Cetin 
1Ege University, Faculty of 
Pharmacy, Dept. of 
Biopharmaceutics and 
Pharmacokinetics, Bornova, 
Izmir. 
2Ege University, Faculty of 
Pharmacy, Dept. of 
Radiopharmacy, Bornova, 
Izmir. 
 
 
 
 
 
 
Abstract 
The aim of this study was to develop a novel HPMCP capsule. The 
HPMCP capsule containing99mTc-DTPA and lactose was evaluated 
in in vitro and in vivo studies. First of all, the HPMCP capsules were 
prepared and characterized with lenght and diameter size, brittleness 
facility, moisture content and microbiological test. In vitro resistance 
and solubility studies of prepared capsules were tested at pH 1.2 and 
pH 7.4 buffers. The radiolabeled HPMCP capsules were 
administrated to fasted volunteers. The disintegration times and 
positions of capsules were recorded by using gamma scintigraphy. In 
vitro studies showed that HPMCP capsules were gastro resistant for 
2 h at pH 1.2 and dissolved at pH 7.4 in 20-25 minutes. The 
radiolabeled capsules did not disintegrate in stomach whereas 
disintegrated in intestines. In conclusion, it was found that, the 
prepared HPMCP capsules can be an alternative to the hard gelatine 
capsules and used for intestinal targeting.  
Keywords: Capsule, hydroxypropylmethylcellulose phthalate 
(HPMCP), gamma scintigraphy, radiolabelling, technetium-99m. 
Introduction 
Controlled drug delivery systems have important 
advantages in treatment of several diseases. In 
delayed-release systems, the enteric coating of 
tablets or capsules modifies the release pattern of 
active ingredient. These types of formulations can 
be designed to release the drug in intestines. Two 
general categories may be distinguished, namely 
enteric coating and controlled release coatings. 
Enteric coating process may be required for some 
active substances irritating the stomach or 
degrading due to acidic pH of the stomach and it 
is insoluble in the gastric juices, but dissolves 
readily on passage into the small intestine. The 
polymers commonly used to achieve enteric 
properties are anionic polymethacrylates 
(copolymerisate of methacrylic acid and either 
methyl-methacrylate or ethyl acrylate cellulose 
based polymers, e.g. cellulose acetate phthalate or 
polyvinyl derivatives, e.g. polyvinyl acetate 
phthalate [1,2]. Polymers with ionizable phthalic 
acid groups dissolve much faster at a lower pH 
than those with acrylic or methacrylic acid groups 
[3].  
 
The most common mode of action of enteric 
coatings is pH related solubility; i.e., insoluble at 
gastric pH but soluble at some pH above 4.5. 
Cellulose acetate phthalate (CAP) and 
hydroxypropylmethylcellulose phthalate 
(HPMCP) are widely used as enteric film coating 
materials. HPMCP is completely insoluble in 
gastric fluid but dissolves above pH 4.5 in 
proximal end of duodenum. [4-7]. In one study, 
enteric coated HPMC capsule has been designed 
to achieve intestinal targeting by manufacturing 
of two different Eudragit® HPMC capsules [1]. 
Cetin et al. International Journal of Drug Delivery 3 (2011) 279-285 
 
 
 
280
Methods based on pH-sensitive delivery systems 
such as enteric coated dosage forms could be a 
simple and practical means for colon-specific 
drug delivery. However such methods do not 
have sufficient site specificity because, with this 
type of dosage form, most of the drug is released 
in the upper small intestine after gastric 
emptying, even though drug release is effectively 
prevented in the stomach. Failure of pH-
dependent system may be expected due to inter 
and intra subject variation of GI pH, pH variation 
due to pathological conditions and diet 
composition [8,9]. 
 
The most commonly used material for 
manufacturing capsules is gelatin. Although it is 
possible to coat hard gelatin capsules. The 
process is at best very sensitive, especially if an 
aqueous coating system is used, and can lead to 
shell embrittlement and poor adhesion of the coat 
to the smooth gelatin surface. A pre-coating can 
reduce interactions between the gelatin and the 
enteric polymer but is time consuming and 
complicated. On the other hand, HPMC capsules 
have been available commercially, mainly to the 
dietary supplement industry as a vegetarian 
alternative to gelatin, for approximately 10 years. 
As HPMC is often used as a pre-coating material 
for enteric coated tablets, it may be expected that 
the application of enteric type polymers to a 
capsule made from HPMC would result in ‘good 
polymer to polymer’ adhesion and compatibility 
[10]. 
 
Scintigraphy is currently one of the most 
powerful techniques for the interpretation of in 
vivo behaviour of pharmaceutical formulations 
[4]. Gamma-scintigraphy is a non-invasive 
method for imaging the in vivo behaviour of 
dosage forms. Gamma scintigraphy is an elegant 
imaging technique which allows the intestinal 
performance of pharmaceutical formulations to 
be visualized [16]. A complete picture of drug 
delivery following oral administration can be 
obtained from sequential images. Determination 
of gastric residence times, times of transit 
through the small intestine and colon, times and 
locations of in vivo release and correlation of 
findings with kinetic data can be evaluated 
[11,12]. 
 
The formulation to be investigated is labelled 
with an appropriate short-lived gamma-emitting 
isotope (99mTc, 153Sm). A gamma-camera can 
then be used to monitor transit past to the 
intended site of delivery. In in vivo studies, 
Technetium 99m-diethylenediaminepentaacetic 
acid (99mTc-DTPA) was used as 
radiopharmaceuticals for gamma-scintigraphy. 
99mTc-DTPA of oral administration does not 
pass through the digestive barrier. After oral 
administration of the 99mTc-DTPA labelled 
substance is used for gastro-oesophageal reflux 
and gastric emptying studies [13,14]. In this 
paper, we describe the manufacture and 
characterization of HPMCP capsules and their in 
vitro/in vivo performance. 
 
Materials and methods  
Materials 
HPMCP (type HP 55, Shin-Etsu Co. Ltd., Japan) 
was a kind gift from Syntapharm (Germany). 
Eosin is supplied from Scarlet Fluka. Technetium 
99m (99mTc)-diethylenediaminepentaacetic acid 
(DTPA) was obtained from the Department of 
Nuclear Medicine of Dokuz Eylül University.  
 
Preparation of the capsules  
The HPMCP capsules were prepared at desired 
sizes using empty gelatine capsules. 12% solution 
of HPMCP (type HP 55) with colouring agent 
(0,1% eosin) in acetone were poured into the 
moulds and allowed to evaporate approximately 
4-8 hours depending on the size of moulds at 
room temperature. After evaporating, the film 
layer was formed inside the capsule.  
Cetin et al. International Journal of Drug Delivery 3 (2011) 279-285 
 
 
Figure 1: Shematic representation of the preparation of HPMCP capsules. 
 
 
 
Figure 2: The photograph of HPMCP capsule. 
 
The gelatine capsules containing HPMCP film 
were dissolved in acidic medium (pH = 1-2) at ≈ 
40 °C. The insoluble HPMCP film layer was 
remained in the form of capsule in water.  Then 
the capsules were dried at room temperature. The 
schematic representation of preparation technique 
and the photograph of HPMCP capsule are shown 
in Figure 1 and 2. 
 
Characterization of HPMCP capsule 
Size of Capsule 
The length and diameter of HPMCP capsules 
were measured by digital micrometer (ID-C112, 
Mitutoyo Corp., Kawasaki, Kanagawa, Japan). 
Their brittleness was measure by using monsanto 
GPIT 9544. 
 
Moisture content 
The HPMCP capsules were weighted at the 
beginning of the study, after that they were dried 
at 105ºC during four hours. The weights of 
capsules were measured at one hour intervals. 
The loss in weight of capsules was calculated 
from below equation. 
100
a
b  capsules ofin weight  lossPercent x=  
 
a is initial weight of capsule, b is differences 
between initial and dried weight of capsules. 
 
Microbiological test 
The HPMCP capsule was dissolved at pH 7,4 
phosphate buffer in sterile condition. The solution 
was cultivated on EMB Agar, Blood Agar and in 
Mueller-Hinton Broth (MHB). These were 
incubated at 370C for 48 hours. At the end of this 
period growth results were evaluated. 
 
 
281
Cetin et al. International Journal of Drug Delivery 3 (2011) 279-285 
 
 
In vitro resistance and solubility studies 
The HPMCP capsules were tested in acidic and 
alkaline media for their resistance and solubility. 
In vitro disintegration and dissolution behaviour 
of capsules were investigated using the gamma 
counter (SESA Uniscaler I /S). For this purpose, 
the capsules were filled with 0.1 g lactose and as 
a radiopharmaceutical agent 99mTc-DTPA was 
added as a tracer. The HPMCP capsules 
containing 0.5 mCi 99mTc-DTPA were placed into 
10 mL 0.1 N HCl solution (pH 1.2) at 50 rpm, 37 
°C. At 30 minutes intervals, the radioactivity in 
test medium was measured for 2 hours (SESA 
Uniscaler-I/S). After two hours, the undissolved 
capsules were washed with distilled water and 
then placed into 10 ml of pH 7.4 phosphate buffer 
at 37 °C. 99mTc-DTPA release from the capsules 
was investigated for 25 minutes(n=6). 
 
In vivo studies  
Four healthy volunteers (1 male, 3 female) of 25-
30 years of age and 50-60 kg body weight 
participated in the study after passing a clinical 
screening procedure that included medical 
history, physical examination. They were non-
alcoholic, non-smokers and were not taken any 
drugs. All participants signed a written informed 
consent. After they had been informed of the 
nature and details of the study in accordance with 
the Turkish Guidelines for ethics. The study 
procedures were in accordance with the Helsinki 
Declaration. 99mTc-DTPA (0.5 mCi) was added 
into the capsules containing lactose. Each fasted 
volunteer ingested 99mTc-DTPA containing 
capsule orally with ≈ 150 mL of water. The 
location of the radiolabelled capsule in the 
gastrointestinal tract of each subject was 
monitored with a gamma-camera (G.E 600 
XR/T). Each volunteer was positioned in front of 
the gamma camera and anterior images were 
taken for 180 seconds at frequent intervals over a 
period of 16–17 h.  The lower part of the sternum 
and umbilicus of volunteers were marked with 
0.003 mCi 99mTc as a marker. 
 
 
Results and discussion 
Characterization of capsule 
Size of Capsule 
The results of the length and diameter size of 
capsule are shown in Table 1. The britrleness of 
HPMCP capsule is about 2±0,045 kg (mean±SD, 
n=6). 
 
Table 1: The length and diameter of capsules. 
Diameter 
(mm) 
Lenght (mm) Measurement 
number 
Body Cap Body Cap 
1 6,930 6,460 18,630 10,990
2 6,850 6,390 18,650 10,940
3 6,920 6,400 18,640 10,960
4 6,900 6,430 18,610 10,930
5 6,870 6,470 18,670 10,980
6 6,910 6,440 18,630 10,950
Average 6,897 6,432 18,638 10,958
SD 0,031 0,032 0,020 0,023 
SD: standard deviation 
 
Moisture content 
The moisture content of capsule was determined. 
HPMCP capsule moisture content was about 
4.8%±0,019 (mean±SD) w/w at the end of 4h. 
The results of the moisture content of capsule (% 
loss in weight of capsule) are shown in Table 2. 
 
Table 2: The moisture content of capsule (% loss 
in weight of capsule) with SD (n=6). 
Time(minute) % loss in weight of 
capsule 
60 4,298±0,023 
120 4,432±0,044 
180 4,835±0,058 
240 4,835±0,019 
 
Microbiological test 
The results of microbiological test are shown that 
no growth was observed on the EMB, Blood 
Agar and MHB in which HPMCP capsules were 
tested for microbiological control.  
 
 
 
 
282
Cetin et al. International Journal of Drug Delivery 3 (2011) 279-285 
 
 
Results of In Vitro Studies 
The release of 99mTc-DTPA from HPMCP 
capsules, in simulated gastric and intestinal media 
was investigated. The dissolution profiles from 
the HPMCP capsule is shown in Figure 3. It was 
seen that 99mTc-DTPA was not released from 
HPMCP capsules during 2 h in pH 1.2. All 
amount of the 99mTc-DTPA was released rapidly 
in pH 7.4 at the end of 25 min. At this pH, the 
capsules completely dissolved. It was considered 
that HPMCP capsule to achieve 2 hour in vitro 
lag time would be suitable to achieve in vivo 
capsule opening either in the intestinal zone. 
 
 
Figure 3:  The in vitro resistance and solubility 
control of HPMCP capsule in acidic and alkaline 
media using 99mTc-DTPA. 
 
 
Figure 4: Time lapse drug delivery from the HPMCP capsules. 
 
 
283
Cetin et al. International Journal of Drug Delivery 3 (2011) 279-285 
 
Results of In Vivo Studies: 
In order to find out the in vivo performance of the 
HPMCP capsules, gamma scintigraphic studies 
were carried out on the capsules, using 99mTc-
DTPA as tracer, in human volunteers.  
 
The locations of the HPMCP capsule in the 
human digestive tract at different times after its 
administration are given in Figure 4. The 
HPMCP formulation was expected to be intact in 
stomach and to dissolve in intestine because of 
alkaline pH. 
 
The difference of capsule transit time can be seen 
in digestive system of volunteers. Gastric 
residence time of HPMCP capsule was 120 
minute in stomach. At 135 minute the capsule 
was in duodenum and at 185 minute the capsule 
was started to dissolve in small intestine. It was 
dispersed in intestine at 430 minute. The small 
intestine transit time for HPMCP capsules ranged 
between 3 and 4 hour. The capsule type remained 
intact in the stomach which confirmed the gastro-
resistant properties of HPMCP polymer. The data 
from this study demonstrate that volunteers dosed 
with HPMCP capsule 99mTc-DTPA as tracer 
disintegration occurred intestinal zone suggesting 
that the volunteer’s intestinal pH was sufficient to 
dissolve the polymer on this formulation and 
thereby provide for intestinal targeting.  
 
Conclusion 
The moisture content of capsule shell must be 
such as to prevent brittleness. It is normally 13.0 
to 16.0%, determined by drying at 105ºC for hard 
gelatine capsules.  The brittleness can be checked 
by at the centre of the capsule against a smooth 
hard surface; the capsule must not shatter [15], 
The moisture content and brittleness of prepared 
HPMCP capsules were found %4.8±0,019, and 
2±0,045 kg, respectively. Also, the brittleness of 
hard gelatine capsule is about 2.1 kg. According 
to this result, HPMCP capsules had low moisture 
content, and their brittleness was resistant to 
applied pressure.   
 
 The HPMCP capsules showed a good correlation 
in in vitro/in vivo conditions as expected. 
According to in vitro study, 99mTc-DTPA 
released from HPMCP capsules was independent 
of time and it was mainly controlled by 
dissolution of the HPMCP polymer. The gamma 
scintigraphic imaging method was utilised to 
obtain visual data about the movement and 
disintegration of the HPMC capsule in the 
human. The HPMCP capsules can be good 
container for intestinal targeting and they are 
convenient for drugs that have gastrointestinal 
adverse effect and site specific delivery into the 
intestine. 
 
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In Vitro and In Vivo evaluation of hydroxypropylmethyl cellulose phthalate capsules

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In Vitro and In Vivo evaluation of hydroxypropylmethyl cellulose phthalate capsules

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