Effect of storage temperature on the dispersibility of commercially available 0.1% fluorometholone ophthalmic suspension.

In this study, we focused on the storage conditions and investigated the effects of low-temperature storage (10°C) on the dispersibility of active components in three formulations of fluorometholone (FLU) suspension eye-drops (one original drug and two generic drugs, P1-P3). For all three eye-drop products, before shaking by hand, white sediment anticipated to be the principal active component was seen at the vial base. In the ordinary-temperature storage group, the FLU contents per drop after shaking by hand were 0.076% in P1, 0.023% in P2, and 0.100% in P3, and the content in P2 was significantly lower than that in P1 and P3. In contrast, almost no dispersion was observed in the low-temperature group. The results after sufficient shaking of these samples with a vortex, in contrast, were such that the FLU contents per drop were 0.063% in P1, 0.086% in P2, and 0.088% in P3; the content in P1 was significantly lower than that in P2 and P3, and there was no difference between P2 and P3. Moreover, we evaluated the dispersibility according to the evaluation "Vs / (ρg - ρf) g." In both the low- and ordinary-temperature storage groups, the value of Vs / (ρg - ρf) g, proportional to the terminal velocity, decreased in the following order: P3 > P1 ≫ P2, and each value in the ordinary-temperature was higher than that in low temperature. The zeta potential decreased in the following order: P2 > P3 ≫ P1. In conclusion, when FLU suspension eye drops are stored at low temperatures until use, such as in a refrigerator, ordinary shaking does not help achieve dispersion to the specified concentration, and even with vigorous shaking with some formulations, the specified concentration cannot be achieved.

Effect of inner physical properties on powder adhesion in inhalation capsules in case of a high resistance device.

The inhalation performance of a dry powder inhaler (DPI) depends on the inhalation patterns of patients, inhalation particle characteristics and inhalation devices. In capsule-based DPIs, the capsule plays an important role in the dispersion of inhalation particles. The present study investigated the effects of inner physical properties of capsules on drug release from capsules-based DPIs with high resistance device. Atomic force microscopy (AFM) was used to evaluate the capsule physical properties, such as the capsule inner structure and surface potential, of three capsules with different compositions (G-Cap, PEG/G-Cap, and HPMC-Cap). As a model dry powder for capsule-based DPIs, the dry powder in Spiriva® Inhalation Capsules containing tiotropium bromide was used. Inhalation performance was evaluated using a twin-stage liquid impinge and Handihaler® (flow rate 30 l/min). The results indicated that the capsule inner surface presented with numerous valleys and mountains, regardless of the capsule type. Furthermore, the valley and mountain areas on the capsule inner surface showed a significantly higher or lower surface potential. Following inhalation of capsule-based DPIs, the drug remained in the valleys on the capsule inner surface; however, no significant difference was observed in the drug release from capsule and lung drug delivery. Therefore, inhalation performance in capsule-based DPIs when a high resistance device, such as Handihaler®, is used at an appropriately flow rate is not markedly affected by the physical properties of the capsule inner surface due to capsule composition.

[Effect of Shelf Life on the Physical Stability of Suspended Ophthalmic Solutions].

Quality changes associated with physical changes in suspended eye drops are difficult to predict. In this study, we attempted to evaluate the aggregation and redispersability in commercially available suspended eye drops (fluorometholone ophthalmic solutions). The 0.1% fluorometholone ophthalmic solutions (the original product and 4 generic products) were gently mixed by hand after short-term (4 months) or long-term (40 months) storage, and the drug concentration in the first drop and physical stability (redispersability and particle size) were measured. All eye drops produced a cloudy precipitate on the bottom surface of the container, and the amount of precipitate decreased with mixing time. The drug concentration per drop in the original product was approximately 70% of the labeled value after mixing 10 times, and the drug particle size was approximately 4 µm. After mixing the generic products stored short-term 10 times, the concentration ranged from less than 50% to almost 100%. In addition, some generic products after long-term storage had a reduced redispersion ability and labeled concentration. These results suggested that at least 10 mixing were required before the using of fluorometholone original product. In addition, some generic products may not provide sufficient drug exposure even when mixed in the same manner as the original products.

Effects of the Ophthalmic Additive Mannitol on Antimicrobial Activity and Corneal Toxicity of Various Preservatives.

Ophthalmic preservatives are indispensable in eye drop formulations, but may be toxic to corneal structures. Corneal damage necessitates the discontinuation of treatment with ophthalmic solutions. Therefore, the development of a new and safe preservative system without corneal toxicity is needed. The present study investigated the effects of mannitol on the antimicrobial activities and corneal toxicities of various preservatives using Escherichia coli and a human corneal epithelial cell line (HCE-T cells). The following preservatives were examined: boric acid (BA), benzalkonium chloride (BAC), methyl parahydroxybenzoate (MP), propyl parahydroxybenzoate (PP), sodium chlorite (SC), and zinc chloride (ZC). The antimicrobial activities and HCE-T-cell toxicities of 50 µg/mL BA, MP, PP, SC, and ZC were reduced by a co-treatment with mannitol (0-300 µg/mL). The suppressed antimicrobial activities of BA, MP, PP, and SC by the co-treatment with mannitol were restored by the application of a mannitol content higher than 500 µg/mL. In contrast to these 5 preservatives, the addition of mannitol did not affect the antimicrobial activity of BAC and attenuated its HCE-T cell toxicity. Therefore, the balance between the contents of mannitol and preservatives is important in co-treatments. The present results will serve as a guide for the future development of eye drop formulations without corneal toxicity.

Evaluation of Dissolution Profile between Original and Generic Products of Zolpidem Tartrate by Microdialysis-HPLC.

The evaluation of the dissolution profile of hypnotic drugs is important to promote switching from original products to generic products by removing distrust in generic hypnotics. In this study, we investigated differences in the dissolution profiles between original and generic products (GE-D, GE-S, and GE-T) in commercially available zolpidem tartrate (ZOL) products using the HPLC method using a connected microdialysis probe (microdialysis-HPLC method). Although the degree of hardness and the disintegration time were not different among the original, GE-S, and GE-T, GE-D was 1.4 times harder than the other products. The disintegration time of GE-D was approximately twice as long as that of the original product. Generic products dissolved rapidly as compared with the original product, however, the dissolution rate in the ZOL powder (milled ZOL product) was not different between the original and generic products. Macrogol 6000 (polyethylene glycol (PEG)-6000) was used in the generic products, and this additive was the only PEG difference from the original product. We investigated whether the PEG in the product affected the solubility of ZOL and found that the addition of PEG-4000 or PEG-6000 significantly increased the dissolution rate. These results suggest that the solubility of ZOL may be increased by PEG when the product is disintegrated, resulting in the increased dissolution rate in the generic products. In conclusion, we found that the difference of PEG affected the dissolution profile in the disintegration process using the microdialysis-HPLC method. This finding can help ensure the safety of milled products and the selection of additives.

Inhibitory effects of devil's claw (secondary root of Harpagophytum procumbens) extract and harpagoside on cytokine production in mouse macrophages.

Successive oral administration (50 mg/kg) of a 50% ethanolic extract (HP-ext) of devil's claw, the secondary root of Harpagophytum procumbens, showed a significant anti-inflammatory effect in the rat adjuvant-induced chronic arthritis model. HP-ext dose-dependently suppressed the lipopolysaccharide (LPS)-induced production of inflammatory cytokines [interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha)] in mouse macrophage cells (RAW 264.7). Harpagoside, a major iridoid glycoside present in devil's claw, was found to be one of the active agents in HP-ext and inhibited the production of IL-1beta, IL-6, and TNF-alpha by RAW 264.7.

Histamine release inhibitory activity of Piper nigrum leaf.

Oral administration of a methanolic extract of Piper nigrum leaf (PN-ext, 50, 200 and 500 mg/kg) showed a potent dose-dependent inhibition of dinitrofluorobenzene (DNFB)-induced cutaneous reaction at 1 h [immediate phase response (IPR)] after and 24 h [late phase response (LPR)] after DNFB challenge in mice which were passively sensitized with anti-dinitrophenyl (DNP) IgE antibody. Ear swelling inhibitory effect of PN-ext (50, 200 and 500 mg/kg, per os (p.o.)) on very late phase response (vLPR) in the model mice was significant but weaker than that on IPR. Oral administration of PN-ext (50, 200 and 500 mg/kg for 7 d) inhibited picryl chloride (PC)-induced ear swelling in PC sensitized mice. PN-ext exhibited in vitro inhibitory effect on compound 48/80-induced histamine release from rat peritoneal mast cells. Two lignans of PN-ext, (-)-cubebin (1) and (-)-3,4-dimethoxy-3,4-desmethylenedioxycubebin (2), were identified as major active principles having histamine release inhibitory activity.