Dosage performance tests:Dissolution test for tablets

Title

Dosage performance tests:Dissolution test for tablets

Objective:

 i) To determine the percentage of the amount of ibuprofen dissolved in the dissolution medium at the wavelength of maximum

ii) To determine the amount of ibuprofen dissolved from UV absorbance at wavelength of 221nm in comparison with standard solution.

Introduction:

            Dissolution test is one of the in vitro tests usually employed to assess the quality of oral pharmaceutical solid dosage forms such as tablets and capsules. Dissolution test s can be used to guide formulation developments, identify critical manufacturing variables, monitor formulation quality from batch to batch, predict the in vivo performances and also serve as a surrogate for bioavailability and bioequivalence. However, the role of the dissolution test has been extended to measure the rate drug release from various other forms such as topical, and transdermal systems and suppositories.

            The tablet that has been used for this experiment is ibuprofen. The basket method is used and a single tablet is placed into the basket to allow dissolution to take place within 30 minutes. The sample is then diluted with dissolution medium (buffer) and tested using the spectrophotometer for the absorption of the wavelength of 221nm.

The percentage amount of ibuprofen dissolved is calculated using this formula:        

A_t/A_s x W/ 50 x 2/25 x P x 900 x25/2 x 100/200

where,

A_t = absorbance of the sample solution

A_s = absorbance of the standard solution

W = weight of ibuprofen reference standard used

P = purity of ibuprofen reference standard

Materials:

·         Ibuprofen tablets

·         Dissolution medium

·         Ibuprofen standard solution

Apparatus:

·         Dissolution tester

·         Spectrophotometer

·         Filter funnel

·         10ml measuring cylinder

·         Dropper

·         50ml volumetric flasks

·         Weighing boat

·         Electronic balance

 Procedure:

1. Each of the dissolution vessels is filled with the buffer solution to 900 ml mark. The temperature is set to 37^oC.

2. The temperature of the dissolution medium is checked. It is ensured to be at 37 ± 0.5^oC.

3. One Ibuprofen tablet is placed into each dry basket assembly.

4. The stirring speed is set to 150 rpm. The basket assembly is lowered into position in a vessel and the operation started.

5. After 30 minutes, 10 ml of the samples of the dissolution medium were withdrawn from each vessel for analysis and the solution was filtered using a suitable filter.

6. A standard solution of ibuprofen is prepared by diluting 10.0 mg of ibuprofen reference standard to 50 ml with dissolution medium.

7. 2.0 ml of the sample solution and 2.0 ml of the standard solution is diluted to 25 ml with dissolution medium in separate volumetric flasks.

8. The absorption of both solutions is measured in a 1 cm cell at a wavelength of 221 nm.

9. The spectrophotometer readings for both solutions were recorded. The percentage amount of ibuprofen dissolved was calculated by using the given formula.

10. From the results obtained, the tablets were determined whether it compiled with the requirements of the British Pharmacopoeia.

Results and calculations:

Type of solution	Spectrophotometer absorbance reading
Standard	1.783
Sample	0.849

Percentage amount of ibuprofen dissolved:

= 0.849/1.783 x 10/50 x 2/25 x 0.98 x 900 x 25/2 x 100/200

= 41.98 %

Discussion:

            Based on the results, the percentage amount of ibuprofen dissolved is 41.98%. Hence, we can conclude that the tablet did not comply with the requirements of British Pharmacopoeia.

            Several errors may have occurred when the experiment was being conducted in the lab. The tablet placed in the basket assembly may have been soaking in water for some time due to the starting trouble caused by the dissolution tester. This may have altered the composition of the ibuprofen tablet itself. Besides, the sample solution was not filtered properly using the filter as per guided by the lecturer, therefore, allowing some small undissolved ibuprofen tablets to be present in the volumetric flask. This would have affected the reading of the ibuprofen in the spectrophotometer as the amount of light absorbed is proportional to the concentration of solute present.

            Moreover, parallax error is prone to occur while measuring the solutions using the measuring cylinder and volumetric flask. The concentration of the solution would have been altered if incorrect amount of solution has been mixed together, thus resulting in the spectrophotometer to project wrong reading of absorption. This can prevented if the experimenter has made sure that his eyes are perpendicular to the plane of measuring cylinder and the to the calibration mark of the volumetric flask.

Questions:

4. Why is dissolution test suitable to be used for batch to batch quality control?

Dissolution test stimulates the availability of active substance and allows the prediction of the time for complete release of the material from the dosage form. As soon as the composition and the manufacturing process are defined, dissolution testing is used in the quality control of scale-up and of production batches to ensure both batch-to-batch consistency and that the dissolution profiles remain similar to those of pivotal clinical trial batches. 

5. Describe other apparatus that you can use to conduct dissolution test apart from the one found in the laboratory.

·         Dissolution apparatus 2- Paddle ( conducts dissolution testing for oral solid dosage forms, mainly tablets)

·         Dissolution apparatus 3- Reciprocating cylinder ( generally used for transdermal dosage forms)

·         Dissolution apparatus 4- Flow- through cell (to benefit from complete flexibility on media volumes and to reproducibly position dosage forms such as powders.  

Conclusion

 From the experiment, the tested ibuprofen is not complied with the British Pharmacopeia as only 41.98% of  the tablet is dissolved during the experiment.

Reference

·         Tablet dissolution testing

http://www.pharma-test.de/manual-tablet-dissolution-testing/

·         Dissolution

http://www.pharmacopeia.cn/v29240/usp29nf24s0_c711h.html

·        Dissolution testers (apparatus)

  http://www.erweka.com/products/category/dissolution-tester-usp-apparatus-1256.html?f=1