Experiment 5 ; Content of Ibuprofen (assay)

Experiment 5

Title : 

Content of Ibuprofen (assay)

Objective : 

To identify the content of ibuprofen.

Experimental method :

1. 20 Ibuprofen tablets that are previously selected at random are weighed and are crushed to powder.

2. A quantity of powder containing 0.5g ibuprofen is extracted and mixed with 20ml
chloroform for 15 minutes and is filtered through a sintered glass crucible (BS Porosity No.1).

3. The residue is washed with 3x10ml chloroform and the combined filtrate is gently evaporated just to dryness in a current of air. The residue is dissolved in 100ml with ethanol (96%) that is previously neutralized to phenolphthalein solution.

4. The solution is titrated with 0.1M sodium hydroxide to end point with phenolphthalein solution as the indicator. The content of ibuprofen is calculated if each ml of 0.1M sodium hydroxide is equivalent to 0.02063g of C13H18O2.

Results and Calculation :

1 tablet of Ibuprofen     = 200mg
20 tablets of Ibuprofen = 20 x 200mg

                                    = 4000mg
                                    = 4g

Calculation to obtain 0.5g Ibuprofen

1 tablet contains 200mg of Ibuprofen with other excipient. Hence, 20 tablets contain 4000mg (4g) Ibuprofen.

Total weight of Ibuprofen powder which contains Ibuprofen and other excipient
= 8.2303g

End point of titration with NaOH = 26.3ml

                                       NaOH + C13H18O2 C13H17ONa + H2O

No. of mole of NaOH used in titration =MV/1000=(0.1 x 26.3)/1000=2.63 x 10^-3 mole

Based on the equation, 

                      1 mole of NaOH = 1mole of C13H18O2
      2.63 x 10-3 mole of NaOH = 2.63 x 10-3 moleof C13H18O2

If of NaOH is equivalent to 0.02063g of Ibuprofen,
Then, Ibuprofen contains in the solution for titration

= (2.63 x 10-3 mole )/(1 x 10-4 mole) x 0.02063g =0.5426g

the content of ibuprofen is 0.5426g

Discussion :

                      Based on the result, we can calculate the standard deviation of the experiment by using the formula below:

                          standard deviation= (Experimental value )/(Theoretical value)  ×100%

                                                     =⃒0.5426/0.5  ⃒×100%

                                                     = 108.52%

                            From the calculation, we obtained a standard deviation of 108.52%. The standard deviation is within 85% to 115% which is based on the range of the British Pharmacopoeia. Thus, the experimental value is considered comply the test. The resulted deviation may be due to several errors which occurred when the experiment was carried out. These errors affect the accuracy of the experiment data.
                           First and foremost, the ibuprofen that we used for the experiment may have expired, causing the loss of active ingredients in the tablets as the active ingredients might have decomposed. Therefore, to increase the accuracy of the experiment, we should use ibuprofen tablets that are not expired.
Besides, when we were crushing the tablets into the powder form, there may be loss of the active ingredients. This is because when we were using mortar and pestle to crush the tablets, some of them would drop out of the pestle, causing the loss of ingredients. Thus, to prevent this to happen, we should try to crush the tablet gently so that the loss of the active ingredient can be reduced.Only that, over-titration would have occurred when we were carrying out titration with the sodium hydroxide. This is due to the titration is too fast that we missed the volume of sodium hydroxide that caused the first change of colour in the solution. Thus, it would better that if we carry out titration slowly drop by drop, this will prevent us from missing the first end point of the titration.

Questions:

1. What are the objectives of the test for the uniformity of diameter and uniformity of content?

The test for the uniformity of diameter is to ensure the tablets produced are of the same and equal diameters. The test for the uniformity of content is to determine whether the individual contents are within limits set with reference to the average content of the sample. It is carried out based on the assay of the individual contents of active substances of a number of single doses.

2. State the types of tablets and capsules that must be tested for uniformity of diameter and uniformity of content.

The types of tablet that must be tested for uniformity of diameter include uncoated and coated tablets with the exception of enteric tablets, film-coated tablets and sugar-coated tablets. As for the uniformity of content, it is applicable for uncoated tablets, coated tablets, effervescent tablets, hard capsules, soft capsules, enteric-coated tablet or capsules and lastly modified-release tablet or capsules.

3. Give reasons for the non-compliance to test of weight.

There are reasons for the non-compliance of the test of weight. One of them is due to the uneven feeding of granules into the die. Besides, the irregular movement of the lower punch will cause variation in capacity of die space.

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

Dissolution test is suitable to carry out batch to batch so that it can ensure the quality and consistency of each and every batch of the product. When the products that manufacturers produced are in a large scale, it is quite impossible to carry out dissolution test for each and every single product. Thus, if we carry out the dissolution test batch to batch, it can be considered as the simplest and fastest way to identify which product fail to pass the test.

5. Explain the difference found in the procedure for the dissolution test in United State Pharmacopoeia and the British Pharmacopoeia.

There are significant difference between the USP and the British Pharmacopoeia. During the dissolution testing in that capsule products, especially those in hard capsules, float because of their fill density is less than 1g mL-1 is preferably to used Apparatus 1 as stated in the USP while the Apparatus 2 is preferably used for tablets. As for the British Pharmacopoeia, it authorize that the use of any product that floats and it has the most precise specification for one, which it is constructed from an acid-resistant metal wire 1mm in diameter and is described as being a metal cage, which the body are held together by double wires in the shape of a cross. It is constructed such that one of the endscan be opened to place the capsule inside and is closed with clasp. The British Pharmacopoeia simply states that for product that floats when using the Apparatus 2, a glass or metal helix should be used to keep the dosage horizontal at the bottom of the vessel.

Conclusion:

The ibuprofen content obtained from the experiment is 0.5426g, which contributes to the standard deviation of the experiment is 108.52%, complying the test of uniformity of content which is within 85% to 115%.