Papers by Pahala Simamora
International Journal of Pharmaceutics, 2001
The solubilization of rapamycin, a poorly water soluble investigational immunosuppressive drug, b... more The solubilization of rapamycin, a poorly water soluble investigational immunosuppressive drug, by facilitated hydrotropy is presented. Partially water-miscible aromatic solutes (such as benzyl alcohol, benzoate, or benzoic acid) can be solubilized by water-miscible cosolvents, such as ethanol and propylene glycol. Once solubilized, the partially miscible aromatic solute becomes a solubilizing agent. This technique yielded a dramatic (>1000-fold) increase in the aqueous solubility of rapamycin.
International Journal of Pharmaceutics, 1994
Journal of Pharmaceutical Sciences, 1995
Formulation pH has been reported to be responsible for the incidence of phlebitis. In this study,... more Formulation pH has been reported to be responsible for the incidence of phlebitis. In this study, the effect of pH on injection phlebitis is investigated. Buffers of varying pHs were examined for their ability to produce phlebitis in rabbits. Thermal measurements as well as visual evaluations were used for phlebitis quantitation. The results show that formulation pH between 3.0 and 11.0 does not contribute to the incidence of phlebitis when administered as an iv bolus injection.
Journal of Pharmaceutical Sciences, 1995
We describe a computational model and an in vitro experiment for assessing whether or not a pH-so... more We describe a computational model and an in vitro experiment for assessing whether or not a pH-solubilized drug has the potential to precipitate upon dilution with blood. The computational model enables an efficient means of selecting buffer concentration and pH, and the in vitro test provides a simple experimental validation. Both means of screening are applied to the formulation of the weakly basic drug levemopamil.HCI. A buffered formulation of levemopamil is chosen from the computational model and shown to be free of precipitation upon dilution in vitro and to not produce phlebitis in the rabbit ear model. In comparison, an unbuffered formulation at the same pH and drug concentration precipitates in vitro and causes significant phlebitis in vivo. The results of this study reinforce the importance of buffering parenteral formulations instead of simply adjusting the pH of the formulation.
Journal of Pharmaceutical Sciences, 1997
Sodium insulin and zinc insulin ocular devices are developed for the systemic delivery of insulin... more Sodium insulin and zinc insulin ocular devices are developed for the systemic delivery of insulin. The devices consist of Gelfoam (absorbable gelatin sponge, USP) as an insulin carrier and do not contain any surfactant or absorption enhancer. Sodium insulin was dissolved in either distilled water, 30% ethanol, or 10% acetic acid for either eyedrop or device preparations. Because of its low solubility in water and aqueous ethanol solution, zinc insulin was dissolved in 10% acetic acid–water solution for eye devices preparation. Commercially availabile Humulin R was selected as another source of zinc insulin and was used as an eyedrop as well as one device preparation. Only 10% acetic acid solution-treated insulin devices produce significant blood glucose reduction. The dose of insulin used in this study is <50% of that used in the reported insulin devices.
Sar and Qsar in Environmental Research, 1993
Sar and Qsar in Environmental Research, 1993
AQUAFAC, a new group contribution method for estimating aqueous activity coefficients, has been a... more AQUAFAC, a new group contribution method for estimating aqueous activity coefficients, has been applied to a large set of organic compounds. The current work introduces 27 new group values for hydrocarbon, halogen, and non-hydrogen bond donating oxygen groups. Group values (q-values) have been derived from a data set of 621 compounds representing over 1700 individual solubility values. No correction factors
Industrial & Engineering Chemistry Research, 1994
Journal of Chemical Information and Computer Sciences, 1993
Page 1. J. Chem. In$ Comput. Sci. 1993,33, 437-4440 437 Melting Point and Normal Boiling Point Co... more Page 1. J. Chem. In$ Comput. Sci. 1993,33, 437-4440 437 Melting Point and Normal Boiling Point Correlations: Applications to Rigid Aromatic Compounds Pahala Simamora, Allan H. Miller, and Samuel H. Yalkowsky&#x27; Department ...
Industrial & Engineering Chemistry Research, 1995
ABSTRACT Simple group contribution methods which incorporate nonadditive, nonconstitutive propert... more ABSTRACT Simple group contribution methods which incorporate nonadditive, nonconstitutive properties are proposed to predict normal boiling points and melting points for aliphatic, non-hydrogen-bonding compounds. Boiling points and melting points are estimated from the ratio of the enthalpy of transition and the entropy of transition. The enthalpy of transition is assumed to be equal to the summation of group values. The entropy of boiling is estimated using a modification of Trouton&#39;s rule, while the entropy of melting is estimated using a modification of Walden&#39;s rule. The root mean square errors for the estimation of boiling points and melting points are 14.4 K and 34.3 K, respectively.
Journal of Pharmaceutical Sciences, 1997
An ocular insert is developed for the controlled systemic delivery of insulin. Commercially avail... more An ocular insert is developed for the controlled systemic delivery of insulin. Commercially available Gelfoam absorbable gelatin sponge, USP, is used in the fabrication of the ocular insert in the form of a matrix system. Two eyedrop formulations and 13 eye device formulations were evaluated. The efficacy of insulin ocular delivery was quantitated by monitoring the changes in its pharmacological response (i.e., blood glucose lowering). The in vivo results from devices containing 0.5 or 1.0 mg of insulin with 20 µg of polyoxyethylene-20-stearyl ether (Brij-78) give a substantial improvement in insulin activity and a significant prolongation in its duration compared with the eyedrops. In addition, the mean blood glucose concentration returns to nearly normal levels within 60 min after the removal of the device. Overall, the application of the Gelfoam device makes it feasible to obtain a prolonged systemic delivery of insulin within the desired therapeutic levels without the risk of hypoglycemia.‡
Journal of Pharmaceutical Sciences, 1996
Journal of Chemical Information and Modeling, 1993
Page 1. J. Chem. In$ Comput. Sci. 1993,33, 437-4440 437 Melting Point and Normal Boiling Point Co... more Page 1. J. Chem. In$ Comput. Sci. 1993,33, 437-4440 437 Melting Point and Normal Boiling Point Correlations: Applications to Rigid Aromatic Compounds Pahala Simamora, Allan H. Miller, and Samuel H. Yalkowsky&#x27; Department ...
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Papers by Pahala Simamora