Noriyuki Namiki

Preparation and evaluation of unpleasant taste-masked pioglitazone orally disintegrating tablets.

This study aimed to evaluate the taste and mouth feel of newly designed orally disintegrating tablets (ODTs) of pioglitazone, which is a typical type 2 diabetes medicine with an unpleasant taste, using a visual analog scale (VAS) analysis. The ODTs were subjected to either of these 2 taste-masking procedures: a physical masking procedure that included coating the inactive core granules with mixture of pioglitazone and Eudragit(®) E PO, followed by mixing the granules with aspartame and other excipients to form the tablet (physical masking ODT); or a gustatory masking procedure that involved blending pioglitazone with both sodium chloride and aspartame, followed by mixing the blend with other excipients to form the tablet (gustatory masking ODT). From the results of the VAS analysis, physical masking could suppress the bitterness but not the astringent; therefore, the overall palatability of the ODT was considered not improved. In contrast, gustatory masking significantly suppressed both the bitterness and astringent, and offered a slight sweetness; therefore, the overall palatability of the ODT was considered improved. In conclusion, VAS is a useful tool to evaluate the taste of ODTs and that gustatory masking can effectively mask the unpleasant taste of pioglitazone ODT.

Effect of granule properties on rough mouth feel and palatability of orally disintegrating tablets

In this study, we evaluated the palatability of orally disintegrating tablets (ODTs) containing core granules with different particle sizes, coating, and types of materials using visual analog scales (VAS). Tableting the core granules into ODTs reduced rough mouth feel and improved overall palatability compared to the ingestion of core granules alone. Moreover, the evaluation performed immediately after spitting out ODTs demonstrated differences in rough mouth feel between ODTs containing placebo and core granules. Rough mouth feel was found to be significantly more intense with core granules with particle sizes ≥ 200 μm. Since ODTs may contain taste-masked particles, palatability of ODTs containing coated core granules was also evaluated. Although coating with polymers impairs palatability, it was improved by coating the outer layer with d-mannitol. The effects on palatability of materials constituting core granules were also evaluated, with reduced rough mouth feel observed with core granules composed of water-soluble additives. Based on these data, receiver operating characteristic analysis was performed to determine the threshold VAS scores at which the subjects felt roughness and discomfort. In addition, the threshold particle size of the core granule contained within the ODT required for feeling roughness was determined to be 244 μm. This study elucidated the effect of the properties of masking particles on the rough mouth feel and palatability of ODTs.

The prediction of the palatability of orally disintegrating tablets by an electronic gustatory system.

In this study, the human gustatory palatability sensation of taste-masked famotidine and amlodipine orally disintegrating tablets (ODTs) was quantitatively predicted by an electronic gustatory system (α-Astree e-Tongue). Furthermore, its use in formulation design was evaluated. The famotidine- and amlodipine-containing ODTs, which were bitter- and highly bitter-tasting, respectively, were prepared using a physical (granules spray-coated with ethyl cellulose) or organoleptic (the addition of a sweetener and a flavor) masking method and combinations thereof. The taste-masking effects of different masking methods on the ODTs were investigated in a human gustatory sensation test. In the test, volunteers scored the overall palatability using a 100mm visual analog scale (VAS). The electronic gustatory system was evaluated using the Euclidean distance (the distance between each drug-containing ODT and its corresponding placebo) and partial least squares (PLS) regression analysis of the sensor response values. A good linear relationship was observed between each ODTs Euclidean distance analysis, PLS regression analysis, and clinical VAS scores. Cross-validation verification of each analysis confirmed the models predictive power. This study suggests that the α-Astree can quantitatively evaluate physical and organoleptic taste masking and that the palatability of unknown formulations can be predicted by Euclidean distance and PLS regression data analysis.

Chronological Effects of Rifampicin Discontinuation on Cytochrome P450 Activity in Healthy Japanese Volunteers, Using the Cocktail Method

Cytochrome P450 (CYP) 1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A are major factors involved in the metabolism of clinically prescribed drugs. Because the time course after drug treatment discontinuation has received little attention, we aimed to clarify the chronological changes of rifampicin‐induced CYP enzyme activities after rifampicin discontinuation. Thirteen volunteers took 450 mg of rifampicin once daily, and the cocktail method, which uses caffeine, losartan, omeprazole, dextromethorphan, and midazolam as CYP‐specific probes, was repeatedly used for the evaluation of CYP levels. Concentrations of probes and metabolites were determined by liquid chromatography–tandem mass spectrometry. Seven‐day rifampicin administration increased CYP2C19 and CYP3A enzyme activities. The induced CYP2C19 and CYP3A activities remained elevated at 4 days after rifampicin discontinuation and returned to baseline levels 8 days after rifampicin discontinuation. CYP1A2 and CYP2D6 enzyme activities showed no significant changes, and CYP2C9 enzyme activity was increased with rifampicin administration, with a tendency toward statistical significance. Drug interactions can occur even after rifampicin discontinuation.

Combination Effect of Physical and Gustatory Taste Masking for Propiverine Hydrochloride Orally Disintegrating Tablets on Palatability

Orally disintegrating tablets (ODTs) containing propiverine hydrochloride (which is extremely bitter and leaves a feeling of numbness in the mouth) were prepared with a combined use of physical and organoleptic taste masking. Propiverine-loaded masking particles (PLMPs) were prepared with different amounts of gastric-soluble coatings as physical masking. ODTs without organoleptic masking were prepared by mixing each group of PLMPs with Ludiflash®, crospovidone, and magnesium stearate. ODTs with organoleptic masking were also prepared by addition of L-menthol, aspartame, thaumatin, and cinnamon. Fifteen-minute dissolution of propiverine in solutions with pH 1.2 was ≥ 85% for all ODTs, whereas that in pH 6.8 solutions was ≤ 85% and increased with physical masking. A single blind randomized crossover trial was conducted. Ten healthy volunteers were asked to quantify the bitterness, numbness, and overall palatability using a 100-mm visual analog scale (VAS) at the period of disintegration as well as 1 and 5 min later. VAS scores of bitterness, numbness, and overall palatability improved along with increasing amounts of physical masking, and the effects persisted for 5 min. VAS scores for numbness increased over time regardless of the amount of physical masking. Bitterness, numbness, and overall palatability were significantly improved by organoleptic masking if the amount of physical masking was small. Combined use of physical and organoleptic masking is useful for improving palatability of ODTs containing propiverine.

Simultaneous and comprehensive in vivo analysis of cytochrome P450 activity by using a cocktail approach in rats.

A cocktail approach can detect the activities of multiple cytochrome P450 (CYP) isoforms following the administration of multiple CYP‐specific substrates in a single experiment. This study aimed to develop a simultaneous and comprehensive in vivo analysis of CYP activity in rats. The rats received an oral administration of losartan (10 mg/kg) and omeprazole (40 mg/kg). Caffeine (1 mg/kg), dextromethorphan (10 mg/kg) and midazolam (10 mg/kg) were administered 15 min later. In the drug‐interaction phase, the rats were treated orally with dexamethasone (80 mg/kg) 24 h before, or with ketoconazole (10 mg/kg), fluvoxamine (100 mg kg) or fluconazole (10 mg/kg) 1 h before the administration of cocktail drugs. The concentrations of the drugs and their metabolites were determined by LC/MS/MS. Plasma concentrations of five CYP substrates and their metabolites were simultaneously evaluated after the oral drug administration. Fluvoxamine and fluconazole significantly increased the Cmax and AUC of caffeine, and the AUC of omeprazole and midazolam. Dexamethasone significantly increased Cmax and AUC of losartan, while it decreased the Cmax of midazolam. Ketoconazole showed no significant effect on the pharmacokinetic parameters of the tested drugs. In conclusion, a cocktail approach was developed for simultaneous and comprehensive analysis of the activities of multiple CYP isoforms in rats. In this approach, the effects of inhibitors and an inducer of various CYP isoforms were examined. Although further studies are necessary to predict the effects in humans, this approach may be expected to serve as a convenient method for detecting drug–drug interactions in rats. Copyright

Skin Permeation of Lidocaine from Crystal Suspended Oily Formulations

ABSTRACT In vitro permeation of lidocaine (lidocaine base, LID) through excised rat skin was investigated using several LID-suspended oily formulations. The first skin permeation of LID from an LID-suspended oily solution such as liquid paraffin (LP), isopropyl myristate (IPM), polyoxyethylene (2) oleylether (BO-2), and diethyl sebacate (DES) was evaluated and compared with that from polyethylene glycol 400 (PEG400) solution, a hydrophilic base. The obtained permeation rate of LID, Japp, from PEG400, LP, IPM, BO-2, and DES was in the order of DES>BO-2 = IPM>LP>PEG400, and increased with LID solubility in the oily solvents, although LID crystals were dispersed in all solvents. Subsequently, oily formulations that consisted of different ratios of the first oily solvent (IPM, BO-2, or DES) (each 0–20%), the second oily solvent (LP) and an oily mixture of microcrystalline wax/white petrolatum/paraffin (1/5/4) were evaluated. BO-2 groups at a concentration of 5% and 10% had the highest Japp among the oily formulations, although a higher BO-2 resulted in lower skin permeation. In addition, pretreatment with BO-2 increased the skin permeation of LID. These results suggest that the penetration enhancing effect by the system may be related to the skin penetration of BO-2 itself. Finally, mathematical analysis was done to evaluate the effect of BO-2, and it was shown that BO-2 improved the LID solubility in stratum corneum lipids to efficiently enhance the LID permeation through skin.

Reduction in the volume of water for ingesting orally disintegrating tablets of solifenacin (Vesicare® OD), and the clinical disintegration time of Vesicare® OD after unit-dose packaging.

This study aimed to determine the amount of water required for ingesting an orally disintegrating tablet (ODT) of solifenacin (Vesicare(®), VES) and VES conventional tablets (VES-CT). We measured the disintegration time of VES-ODT in the oral cavity (clinical disintegration time) before and after unit-dose packaging. Thirty healthy volunteers participated in this randomized crossover trial. The participants were asked to drink water during the intake placebos of VES and after the disintegration of placebos of VES-ODT in their oral cavity. The amounts of water required for ingesting placebos of VES-CT and of VES-ODT were 42.8±27.0 mL and 20.0±23.7 mL, respectively, which indicated that the amount of water required for ingesting ODTs was significantly lesser than that for ingesting CTs. Furthermore, 5 (16.7%) participants did not require water for ingesting the ODTs. Clinical disintegration time of VES-ODT was 21.4s in 10 healthy volunteers. This clinical disintegration time did not change significantly after unit-dose packaging or subsequent storage for 56 days. This study showed that the amount of water required for ingesting VES-ODT is lower than that for ingesting VES-CT.

Development of Gummi Drugs of Aripiprazole as Hospital Formulations

About half of patients with schizophrenia have poor adherence to taking medication, so many have recurrence, therefore, providing formulations that enable patients to continue their medication without interruption is important. We aimed to develop a gummi drug that contains aripiprazole (which can reduce schizophrenia and manic symptoms in bipolar disorder). We were able to develop gummi drugs (OD-G, PW-G and OS-G) using three commercially available aripiprazole products (Abilify® orally disintegrating tablets, powder formulation, and oral solutions, respectively) as hospital formulations. Furthermore, we developed improved OD-G (iOD-G), which contained high aripiprazole content. Pharmaceutical characteristics of iOD-G were demonstrated to be suitable for hospital formulations, and iOD-G could be stored for ≤1 month. No significant differences in the dissolution and pharmacokinetics of divided portions of iOD-G were observed when compared with commercially available aripiprazole products. This study confirmed that new dosage forms of aripiprazole in gummi drugs can be developed as hospital formulations, which will contribute to improve medication adherence of patients.

Pharmaceutical Development of a Parenteral Formulation of Conivaptan Hydrochloride

Conivaptan hydrochloride injection (Vaprisol®) was developed for the treatment of hyponatremia. Because the drug is very slightly soluble in water, pH control and cosolvency techniques were used to achieve the optimum concentration required for clinical trial material. Stability studies on retained samples of the clinical trial material for early-phase trials showed white visible particulates mainly in the headspace of the glass ampoule long after completion of the trials. The mechanism for generation of the particulate matter was formation of freebase of conivaptan hydrochloride because of increase in pH. The pH of the formulation for late-phase clinical trials, primary stability studies, and commercial production was fine-tuned to prevent particulate formation. The formulation contains propylene glycol and ethanol. Considering the nature of the cosolvent used in the formulation, the amount of di(2-ethylhexyl)phthalate (DEHP) delivered from an infusion system was evaluated, and we confirmed that the level of DEHP was lesser than that mentioned in the guideline. In the course of the scale-up studies for commercialization, the formulation failed the filter integrity test after the compounding solution was filtered. The dimethylsiloxane extracted from the silicon tubing used for solvent transfer coated the filter surface, which resulted in suppression of the bubble point value. The formulation and manufacturing process enabled conivaptan hydrochloride to be approved and launched in the market as a parenteral formulation. LAY ABSTRACT: Formulation scientists have recognized a trend that promising new chemical entities in the drug discovery phase often do not have ideal physicochemical properties for formulation. In particular, poor solubility is one of the challenges for development of a parenteral dosage form. Here, we describe the case of such a new chemical entity, a very slightly soluble hydrochloric salt, which was handed over from a drug discovery research laboratory to a pharmaceutical laboratory. pH control and cosolvency techniques were used to achieve the optimum concentration required for the product. However, a couple of issues emerged; we performed confirmatory studies in the course of development, and the results of these studies were used to design the formulation and manufacturing process. Most prominent issues were particulate matter formation on the inner surface the headspace of the ampoule and failure of the filter integrity test. In addition, we discuss the root causes and the mechanisms of the above issues and the measures taken to prevent them. A part of them are crucial, and information obtained from this study is important for development of new chemical entities as injectables in the future.