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The Effect of Selected Water-Soluble Excipients on the Dissolution of Paracetamol and Ibuprofen

Shaw, Lance R., Irwin, William J., Grattan, Tim J. and Conway, Barbara R (2005) The Effect of Selected Water-Soluble Excipients on the Dissolution of Paracetamol and Ibuprofen. Drug Development and Industrial Pharmacy, 31 (6). pp. 515-525. ISSN 0363-9045

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The purpose of this investigation was to study the dissolution behavior of paracetamol and ibuprofen in the presence of a range of selected potential excipients. First, a pH-solubility profile was generated for both drugs, and the effect of changing hydrodynamic conditions on the intrinsic dissolution rate was investigated. It was established that both drugs dissolved according to the diffusion-layer model. Paracetamol solubility (approximately 20.3 mg mL− 1) did not vary from pH 1.2–8.0, corresponding to the in vivo range in the gastrointestinal tract. Ibuprofen had an intrinsic solubility of approximately 0.06 mg mL− 1, and pKa was calculated as 4.4. Second, the effects of selected potential excipients (lactose, potassium bicarbonate, sodium bicarbonate, sodium chloride, and tartaric acid) were evaluated by measuring the effect of the inclusion of each additive in the dissolution medium on drug solubility, drug intrinsic dissolution rate, and solution viscosity. The results were evaluated using the diffusion-layer model, and it was determined that for paracetamol, the collected data fitted the model for all the excipients studied. For ibuprofen, it was found that there were differences between the excipients that raised the solution pH above the pKa to those that did not. For the excipients raising the pH above the pKa, the effect on intrinsic dissolution rate was not as high as that expected from the change in drug solubility. It was postulated that this might be due to lack of penetration of the excipient into the drug boundary layer microenvironment. Formulators may calculate the effect of adding an excipient based on solubility increases but may not find the dissolution rate improvement expected.

Item Type: Article
Subjects: Q Science > Q Science (General)
Q Science > QD Chemistry
Schools: School of Applied Sciences
School of Human and Health Sciences > Institute for Skin Integrity and Infection Prevention
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Depositing User: Sharon Beastall
Date Deposited: 04 Nov 2010 12:33
Last Modified: 28 Aug 2021 11:01


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