CONTENT OF IBUPROFEN

Objectives :To determine the content of ibuprofen whether it tally to the value stated.

Procedures :

1.      20 Ibuprofen Tablets were weighed and powdered.

2.      A quantity of powder containing 0.5 g ibuprofen (0.977g) was extracted with 20 ml chloroform for 15 minutes and filtered.

3.      The residuewas washed with 3 × 10 ml chloroform and gently the combined filtrate was allowed to evaporate just to dryness in a current of air. The residue was dissolved in 100 ml with ethanol (96%) previously neutralized to phenolphthalein solution.

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

Calculation :

Weight of weighing boat + powder (20 ibuprofen tablet)	10.9963g
Weight of weighing boat	3.1796g
Weight of powder (20 ibuprofen tablet)	7.8167g

Calculation to get 0.5g ibuprofen,

1 tablet contains 200mg of ibuprofen and the other excipients.

Hence, 20 tablets contain 4000mg (4g) ibuprofen.

Thus, 0.9770g of powder was weighed and dissolved in 20ml chloroform.

Results :

C₁₃H₁₈O₂  +NaOH                        C₁₂H₁₇COONa + H₂O

The end point of titration= 14.6 mL

Number of mole of sodium hydroxide needed to react with ibuprofen,

N_NaOH= Volume x Molar Concentration

               = 14.6mL x 0.1M

               = 0.00146 mol

From the chemical equation,

Number of mole of ibuprofen  Number of mole of sodium hydroxide used

N_Ibuprofen = 0.00146 mol

Mass of ibuprofen,

Mass_Ibuprofen=  Number of mole x Molar mass of C₁₃H₁₈O₂

                    =  0.00146mol x (13x12.01 + 18x 1.008 + 2x16.00)g mol^-1

                    =  0.00146mol x206.274 g mol^-1

                    =  0.30116 g

                    0.3012g

Discussion :

From the experiment, 0.3012g of C₁₃H₁₈O₂was neutralized by 14.6ml of 0.1M NaOH.

Percentage of deviation =×100
                                    = × 100

                                    =  60.24%

The experimental value is highly deviated from the theoretical value, some random or systemic errors might occur. It is because the acceptable range for the content deviation is between 85%- 115% but the experimental value is only 60.24%. Supposedly, the experiment should be repeated by using a new batch of ibuprofen as serious random or systemic error might have occurred. However, due to time limitation, the experiment was not repeated. For instance, fine powder of ibuprofen may escape as they are too light and easily dispersed in the air. Hence, this may cause loss of active ingredient in ibuprofen and affect the final result. Next, the fine powder cannot be transferred completely from one apparatus to another (for example from pestle to weighing boat), some powder may adhere to the inner wall of apparatus and results in inaccurate amount of ibuprofen weighted. Other than that, parallax error may occur during taking reading from the measuring cylinder. Also, filter paper was used instead of sintered glass crucible. Hence, the pore on filter paper might be bigger and allowed some excipients to pass through and impure ibuprofen was extracted. Other than that, the ibuprofen used was expired hence the active ingredient in it may degraded or spoiled. This may affects the amount of sodium hydroxide needed to neutralize the impure ibuprofen.

Those errors can be avoided by improving the steps of carrying out the experiment. As fine particle size of powder is a systemic error, repeating and averaging the results can minimize the deviation and get a more precise result. Parallax error can be eliminated by placing the eye at the position perpendicular to the scale on measuring cylinder or burette. Sintered glass crucible should be used to get the pure ibuprofen. New batch of ibuprofen should be used to eliminate the problem of expired active ingredient.

Conclusion :

0.3012g of ibuprofen active ingredient was obtained from the ibuprofen tablet. The content of active ingredient is not tally with the theoretical dosage expected. The percentage of deviation should be in the range of 85%-115% but the experimental value is 60.24%. The experiment should be repeated by using a new batch of ibuprofen to determine whether it fall in the range of 75%-125% so that the result is acceptable.

Question 5

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

In dissolution test for capsule, it was stated in USP uses the rotating paddle from about one-third of its capsule products. The pharmacopoeias have attempted to overcome the problem of capsules floating by the use of a sinker and there are differences in those prescribed by the 3 major pharmacopoeias. The BP authorizes the use of one any product that floats and it has the most precise specification for one. It is constructed from an acid-resistant metal wire. The PhEur simply states that for products that float when using apparatus no.2, a glass or metal helix should be used to keep the dosage form horizontal at the bottom of the vessel. This sinker must be made from substances that are chemically inert in the media for it to be used in a dissolution test.