Development and Validation of an LC-MS/MS Assay to Quantitate 2',4',6'-Trihydroxyacetophenone in Rat and Dog Plasma and its Application to a Pharmacokinetic Study.

In the present study, a simple, rapid, and reliable bioanalytical method was developed using liquid chromatography with tandem-mass spectrometry (LC-MS/MS) to quantify 2',4',6'-trihydroxyacetophenone (THAP) in rat and dog plasma with 2',4',6'-trihydroxybenzaldehyde as an internal standard (IS). The LC-MS/MS instrument was operated in the multiple reaction monitoring (MRM) mode to detect THAP at m/z transition 166.89 > 82.8 and IS at 152.89 > 82.8, respectively. A simple, one-step protein precipitation (PP) method was employed with acetonitrile for sample preparation. Utilizing a Gemini C18 column, THAP and IS were separated with an isocratic mobile phase consisting of 10 mM ammonium acetate and methanol (10:90, v/v) at a flow rate of 0.2 mL/min. Total chromatographic run time was 2.5 min per sample injection. The standard calibration curve for THAP was linear (r2 ≥ 0.9987) over the concentration range of 0.1 to 100 µg/mL with the lower limit of quantitation (LLOQ) of 0.1 µg/mL (S/N ratio > 10). According to the regulatory guidelines from the U.S. Food and Drug Administration (FDA) and the Korea Ministry of Food and Drug Safety (MFDS), our newly developed biomedical analytical method was fully and adequately validated in terms of selectivity, sensitivity, linearity, intra- and inter-day precision and accuracy, recovery, matrix effect, stability, and dilution integrity. Our validated assay was successfully utilized in a nonclinical pharmacokinetic study of THAP in rats and dogs.

Formulation, release characteristics and bioavailability of novel monolithic hydroxypropylmethylcellulose matrix tablets containing acetaminophen.

Effect of incorporating pharmaceutical excipients on the in vitro release profiles and the release mechanism of monolithic hydroxypropylmethylcellulose (4000 cps) matrix tablets (m-HPMC tablets) in terms of mimicking the dual drug release character of bi-layered Tylenol ER tablets was studied. We also compared the in vitro release profiles of optimized m-HPMC matrix tablet and Tylenol ER tablet in water, pH 1.2 gastric fluid, and pH 6.8 intestinal fluid, and in vivo drug bioavailabilities in healthy human volunteers. Acetaminophen was used as the model drug. The m-HPMC tablets were prepared using a wet granulation method followed by direct compression. Release profiles and swelling rates of m-HPMC tablets were found to be highly influenced by the types and amounts of pharmaceutical excipients incorporated. Starch 1500 (Prejel) and sodium lauryl sulfate (SLS) played a key role in determining the dissolution rate of m-HPMC tablets. Additional excipients, i.e., microcrystalline cellulose (Avicel PH101) and NaH2PO4 were used to tune the release profiles of m-HPMC tablets. The effect of pharmaceutical excipients on drug release from HPMC-based matrix tablets was found to be mainly due to a change in hydrophilic gel expansion and on physical interactions between the drug and HPMC. The optimized m-HPMC tablet with a balanced ratio of Prejel, SLS, Avicel PH101, and NaH2PO4 in the formulation showed dual release profiles in water, pH 1.2 gastric fluid, and pH 6.8 intestinal fluid in vitro. Dual release was defined as immediate drug release within few minutes followed by extended release over 8 h. The similarity factors of m-HPMC tablets and bi-layered Tylenol ER tablets were 79.8, 66.1, and 82.7 in water, gastric fluid and intestinal fluid, respectively, indicating the equivalence of the two release profiles. No significant in vivo bioavailability differences were observed in healthy human volunteers. The developed m-HPMC tablet with dual release characteristics can be easily prepared using a conventional high-speed tablet machine and could provide an alternative to commercially available bilayered Tylenol ER tablets.

Effect of solvents on physical properties and release characteristics of monolithic hydroxypropylmethylcellulose matrix granules and tablets.

Effect of solvents on physical characteristics and release characteristics of monolithic acetaminophen (APAP) hydroxypropylmethylcellulose (HPMC) matrix granules and tablets were examined. Various types and amounts of solvents were employed for granulation and cOAting. APAP and other excipients were mixed and were then wet-granulated in a high-speed mixer. The dried granules were then directly compressed and film-coated with low viscosity grade HPMC. As the amount of water increased, the size of granules also increased, showing more spherical and regular shape. However, manufacturing problems such as capping and lamination in tableting occurred when water was used alone as a granulating solvent. The physical properties of HPMC matrix granules were not affected by the batch size. The initial release rate as well as the amount of APAP dissolved had a tendency to decrease as the water level increased. Addition of nonaqueous solvent like ethanol to water resulted in good physical properties of granules. When compared to water/ethanol as a coating solvent, the release rate of film-coated HPMC matrix tablets was more sensitive to the conditions of coating and drying in methylene chloride/ethanol. Most of all, monolithic HPMC matrix tablet when granulated in ethanol/water showed dual release with about 50% drug release immediately within few minutes followed by extended release. It was evident that the type and amount of solvents (mainly water and ethanol) were very important for wet granulation and film-coating of monolithic HPMC matrix tablet, because the plastic deforming and fragmenting properties of material were changed by the different strengths of the different solvents.