1. Rathapon Asasutjarit, Ph.D.
Development of Thermoresponsive Diclofenac Ophthalmic In Situ Gels Formulaitons By
Rathapon Asasutjarit, Ph.D.
Department of Pharmaceutical Technology,
Faculty of Pharmacy, Rangsit University
Asira Fuongfuchat, Ph.D.
National Metal and Materials Technology center,
National Science and Technology Development Agency (NSTDA)

2. Outline Introduction Objectives Methods Results and discussion
Conclusions
Acknowledgements

3. Introduction
Eye drop solution: convenient to use by instilling into conjunctival sac of
the eye with accurate dose.
Bioavailability is very poor: blinking reflex and lacrimal secretion.
- Inserts, ointments and suspensions.
Eye drop solution
Insert
Ointment

4. - In situ gels: pH, specific ion and temperature
- The thermoresponsive in situ gel is an in situ gel system responding to a
shift in temperature.
- It is liquid at low temperature and becomes gel when in contact with
higher temperature.

5. Diclofenac is one of non-steroidal anti-inflammatory drugs approved for
ocular use.
Diclofenac is available in the drug market as an eye drop solution. It has
been used intensively in the case of post-op inflammatory with 3-4
times of administration.
Thus, minimized frequency of administration, once or twice daily, is
necessary for increasing patient compliance.

6. - My previous work (Asasutjarit, 2008):
- Formulation of thermoresponsive diclofenac ophthalmic in situ gels
contained either
: Pluronic F127 (Poloxamer 407) or
: Combination of Pluronic F127 and hydroxypropylmethylcellulose
- Phase transition temperatures were lower than room temperature.

7. Objectives
The purposes of this study were to develop and to evaluate the formulation of thermoresponsive diclofenac ophthalmic in situ gels possessing optimum phase transition temperature.

8. Methods, Results and discussion
Preparation of thermoresponsive diclofenac
ophthalmic gels and products evaluation
: 0.1% w/w diclofenac sodium ophthalmic gels containing
various gelling agent contents
: prepared on a weight basis by the cold method
Formulation (Rx)
Gelling agent (%w/w)
F127
F68
Carbopol 940
1. F127-20 20
2. F F68-8 8
3. F F68-11 11
4. F F68-11+C.1
0.1
5. F F68-11+C.3
0.3
6. F F68-11+C.5
0.5

9. : Phosphate buffer pH 7.4 was used in the formulations as vehicle except
for the formulations containing carbopol 940, phosphate buffer pH 5.5
was used.
: All samples were analyzed spectrophotometrically for the content
uniformity at a wavelength of 276 nm.
: Only samples with diclofenac sodium content within 100± 10% of
labeled amount were accepted.
: They were measured their pH in triplicate by using a pH meter.

10. 2. Determination of phase behavior and sol-gel
transition temperature of thermoresponsive gels
2.1 Test tube inverting method
: 2±1°C (storage temperature)
: 27±1°C (room temperature)
: 35±1°C (ophthalmic temperature).

11. - storage modulus (G´) and loss modulus (G´´) at varied temperatures
2.2 Temperature sweep test : Rheometer
- storage modulus (G´) and loss modulus (G´´) at varied temperatures
Gel phase
Phase transition
Sol phase

12. Preparation and evaluation of thermoresponsive diclofenac ophthalmic gels (continued)
Formulation (Rx)
%Labeled amount
*Flow ability at various temperatures
Sol-gel transition temperature (°C) pH
2±1 (°C)
27±1 (°C)
35±1 (°C)
1. F127-20
103.2±1.0
+++ -
20.7±0.1
7.4±0.1
2. F F68-8
103.3±1.2 +
27.2±0.3
7.3±0.1
3. F F68-11
102.6±0.6
31.6±1.8
4. F F68-11+C.1
103.2±0.8
32.7±1.1
5.4±0.1
5. F F68-11+C.3
103.3±0.9
31.7±0.5
4.8±0.1
6. F F68-11+C.5
36.3±1.4
4.7±0.1
(n=3, mean± SD),
*Flow ability: +++ = very good; ++ = good; + = flow; - = not flow

13. 3. Gelling capacity test Drop 20-μl of samples
A test tube containing 2-ml of simulated tear fluid (STF) (pH 7.4)
equilibrated at 35 °C.
The visual assessment of gel formation and dissolution
was performed in triplicate (Wu et al., 2007).

14. Time for remaining gel in STF (min)
Formulation (Rx)
Time for remaining gel in STF (min)
3. F F68-11
20.2±0.8
4. F F68-11+C.1*
40.4±0.7
5. F F68-11+C.2
45.3±0.6
6. F F68-11+C.3
49.0±0.4
The formulations containing carbopol 940 were eroded by STF more
slowly than the formulation without carbopol 940 markedly.
- This is probably that carbopol 940 consisting in the formulations led to
more stiff gel when pH of the environment was increased.
- Since formulation Rx 4. (F F68-11+C.1) had an optimum sol-gel
transition temperature, pH and gelling capacity, it was chosen as a
representative for the further experiments.

15. 4. Steady shear sweep test
: The experiment was carried out at 27±1 °C and 35±1 °C by a
rheometer for determination of flow behavior of Rx 4. (F F68-
11+C.1)
: The initial and final shear rates were 0.05 and 100 s-1, respectively.

16. Pseudoplastic flow
Rheogram of Rx 4. (F F68-11+C.1)

17. Viscosity profile of Rx 4. (F127-20+F68-11+C.1)
- Ocular shear rate is about 0.03 s-1 during interblinking and 4,250-
28,000 s-1 during blinking.

18. 5. Eye irritation test : 4-New Zealand white rabbit
20-µl of the sample was instilled into the conjunctival sac of
rabbit’s right eye
The left was kept as a control without manipulation.
0, 5, 10, 30 min, 1, 6, 12, 24, 48 and 72 hours

19. (DiPasquale and Hayes, 2001)
Lesions
Grades
Cornea
No ulceration or opacity
Scattered or diffuse areas of opacity (other than slight dulling of normal
luster), details of iris clearly visible 1
Easily discernible translucent area, details of iris slightly obscured 2
Nacreous area, no details or iris visible, size of pupil barely discernible 3
Complete corneal opacity, iris not discernible 4
Iris
Normal
Markedly deepened folds, congestion, swelling, moderate circumcorneal
injection,(any o these separately or combined) iris still reacting to light
(sluggish reaction is positive)
No reaction to light, hemorrhage, gross destruction(any or all of these)
(DiPasquale and Hayes, 2001)

20. (DiPasquale and Hayes, 2001)
Lesions
Grades
Conjunctive
Redness (refers to palpebral and bulbar conjunctivae,
excluding cornea and iris)
Vessels normal
Some blood vessels definitely hyperemic (injected) 1
Diffuse, crimson color, individual vessels not easily discernible 2
Diffuse beefy red 3
Chemosis
No swelling
Any swelling above normal (includes nictitating membranes)
Obvious swelling with partial eversion of lids
Swelling with lids about half closed
Swelling with lids more than half-closed 4
(DiPasquale and Hayes, 2001)

21. Results of eye irritation test of Rx 4. (F127-20+F68-11+C.1)
Lesions
Grades
Cornea
No ulceration or opacity
Iris
Normal
Conjunctive
Vessels normal
Chemosis
No swelling b
a: the test eye
b: the controlled eye

22. 6. Diclofenac absorption in the eye
- 8-New Zealand white rabbit
Group 1 : Rx 4. (F F68-11+C.1)
Group 2 : Diclofenac eye drop solution
(Original)
- Sampling time: 5, 10, 30 min,
1, 6, and 12 hours,
- Sampling volume: 200 µl
- Zoletil 100® im
- High-performance liquid chromatrography (HPLC)

23. Diclofenac concentrations in aqueous humor
Cmax gel = 3,900 ng/ml
Rx 4. (F F68-11+C.1)
Cmax solution = 1,517 ng/ml
Diclofenac eye drop solution (Original)
Diclofenac concentrations in aqueous humor

24. Conclusions - 20% w/w pluronic F127, 11% w/w pluronic F68 and 0.1% w/w
carbopol 940.
- Exhibited solution character predominantly at the storage temperature
and room temperature and became gel at the ophthalmic temperature.
- Sol-gel transition temperature was 32.7±1.1 °C.
- It was convenient to use without keeping in a refrigerator.
- It did not cause eye irritation in rabbits.
- It increased concentration of diclofenac in aqueous humor and
prolonged the contact time of diclofenac in the eye.
- This formulation had a potential for the further study in patients
suffering from inflamed eye.

25. Acknowledgements The authors gratefully acknowledge
- Mr. Chanwit Kammat,
- Mr. Thumrongrat Pukpinyo,
- Ms. Watunya Witisil,
- Ms. Suthira Thansanchokpibull
- Ms. Susiri Preedasuttichit
- Ass. Prof. Aree Thayananuphat, DVM, Ph.D.
- Research Institute, Rangsit University
for the research grant No. 33/50.

26. Thank you