Modelling S-shaped dissolution curves

Kervinen, Lasse; Yliruusi, Jouko

doi:10.1016/0378-5173(93)90270-p

Cited by 21 publications

(10 citation statements)

References 7 publications

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“…Symbols 'a' and 'b' represent scale and shape parameters, respectively. The Weibull function was chosen due to its prior success in modeling S-shaped dissolution curves, like the ones seen for other solid dosage forms (21). One of the drawbacks previously reported for the Weibull model was its empirical nature.…”

Section: Dissolutionmentioning

confidence: 99%

Conversion of Nanosuspensions into Dry Powders by Spray Drying: A Case Study

2008

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Purpose. Drying of nanosuspensions can cause destabilization of the particles, leading to irreversible aggregation. In order to prepare an effective solid dosage form for a nanosuspension, it is imperative that the spray-dried nanoparticles should go back to their original particle size when reconstituted in an aqueous system. This case study examines impact of various formulation and processing parameters on redispersibility of the spray dried nanoparticles. Methods. Nanosuspensions were prepared using the microprecipitation-homogenization process. Spray drying of nanosuspensions was achieved using a lab-scale Buchi spray dryer.Results. Formulation components appeared to have the most significant impact on redispersibility of spray dried particles. Absence of surface charge led to particles that could not be redispersed. On the other hand, charged particles stabilized with an appropriate sugar led to spray dried powders that were flowable and easily redispersible. Dissolution testing showed the presence of two phases-a lag phase that represented dispersion of the loose aggregates, and dissolution of the dispersed nanoparticles. Conclusions. Nanosuspensions of a poorly soluble drug could be spray dried to obtain flowable powders that could be easily redispersed. These optimized powders also showed significantly improved dissolution rates as compared to the micronized drug, or unoptimized nanosuspensions.

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Section: Dissolutionmentioning

confidence: 99%

Conversion of Nanosuspensions into Dry Powders by Spray Drying: A Case Study

2008

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“…[19][20][21][22] Triphasic or sigmoid release curves were found to be best described by the Weibull function. 23,24 The usefulness of the Weibull function in modeling drug release from extended release dosage forms such as biodegradable microspheres was recognized at the AAPS/FIP conference. 7 The attendees recommended this function as a curve fitting approach to model in vitro release.…”

Section: E555mentioning

confidence: 99%

A model-dependent approach to correlate accelerated with real-time release from biodegradable microspheres

2005

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The purpose of this study was to determine the feasibility of applying accelerated in vitro release testing to correlate or predict long-term in vitro release of leuprolide poly(lactideco-glycolide) microspheres. Peptide release was studied using a dialysis technique at 37°C and at elevated temperatures (50°C-60°C) in 0.1M phosphate buffered saline (PBS) pH 7.4 and 0.1M acetate buffer pH 4.0. The data were analyzed using a modification of the Weibull equation. Peptide release was temperature dependent and complete within 30 days at 37°C and 3 to 5 days at the elevated temperatures. In vitro release profiles at the elevated temperatures correlated well with release at 37°C. The shapes of the release profiles at all temperatures were similar. Using the modified Weibull equation, an increase in temperature was characterized by an increase in the model parameter, α, a scaling factor for the apparent rate constant. Complete release at 37°C was shortened from 30 days to 5 days at 50°C, 3.5 days at 55°C, 2.25 days at 60°C in PBS pH 7.4, and 3 days at 50°C in acetate buffer pH 4.0. Values for the model parameter β indicated that the shape of the release profiles at 55°C in PBS pH 7.4 (2.740) and 50°C in 0.1M acetate buffer pH 4.0 (2.711) were similar to that at 37°C (2.677). The E a for hydration and erosion were determined to be 42.3 and 19.4 kcal/mol, respectively. Polymer degradation was also temperature dependent and had an E a of 31.6 kcal/mol. Short-term in vitro release studies offer the possibility of correlation with long-term release, thereby reducing the time and expense associated with longterm studies. Accelerated release methodology could be useful in the prediction of long-term release from extended release microsphere dosage forms and may serve as a quality control tool for the release of clinical or commercial batches.

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“…With other forms of s(t), it yields various S-shaped profiles; examples are provided with s(t) being a linear or quadratic function of time. 12 The Weibull model can be obtained with a power function of time s(t) ‫ס‬ ␤t ␥−1 . Dissolution data were obtained for the reference formulation via standard dissolution test apparatus, and the dissolution curve was also Weibull-shaped.…”

Section: Discussionmentioning

confidence: 99%

“…Microspheres of this formulation containing a 5-mg/kg body weight dose of octreotide were mixed within a vial with 1.5 mL of vehicle solution (phosphate buffered solution of pluronic and sodium carboxymethylcellulose containing benzyl alcohol, pH ‫ס‬ 7.0), and injected im to eight 4-month-old male rabbits (strain: Chinchilla bastard; weight at delivery: 2.7-3.1 kg). Blood was collected 2 days before administration and at 10 and 30 min, at 1, 2, and 5 h, and at 1,2,5,7,9,12,14,16,19,20 or 21, 21 or 23, 26, 28, 30, 34 or 33, 36, 41, 43, 47 and 49 days after administration. Octreotide was measured by radioimmunoassay.…”

Section: Datamentioning

confidence: 99%

“…10 In the same field, a number of empirical models for drug dissolution have been developed. 11,12 To the best of our knowledge, no kinetic model describing a combination of erosion and diffusion processes has been applied to the whole in vivo profile of long-acting release drugs. Based on the previous theoretical works, we developed a general model to describe the physicochemical mechanisms of release of octreotide from long-acting formulation OncoLAR™.…”

Section: Introductionmentioning

confidence: 99%

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