• YAKHAK HOEJI
• /
• v.25 no.4
• /
• pp.187-192
• /
• 1981

In order to increase the dissolution rate on the mixture of sulfamethoxazole and trimethoprim (SMX-TMP), their coprecipitates with polyvinylpyrrolidone (PVP) were studied. Coprecipitates prepared with various ratios of SMX and TMP were examined such as hygroscopicity, apparent solubility, apparent partition coefficient and the dissolution behavior of SMX-TMP's coprecipitates and their physical mixtures. The hygroscopicity of coprecipitates were less than that of physical mixtures. The apparent solubility and dissolution rate of SMX-TMP's coprecipitates were found to be greatly increased. The dissolution rates of SMX and TMP in the coprecipitates were decreased when the ratio of two ingredients to PVP was smaller, and the dissolution rate of SMX was increased when the ratio of SMX to TMP was larger.

• Journal of Pharmaceutical Investigation
• /
• v.6 no.3
• /
• pp.48-57
• /
• 1976

An enhancement in the dissolution rate of the drug should facilitate its GI absorption if the absorption process is dissolution rate limited. One of the need for the techniques that can potentially enhance the dissolution rate and extent of absorption of hydrophobic drugs is the formation of coprecipitates with pharmacologically inert, polymeric materials. The physicochemical modification offers the advantage of possibly enabling one to administer the drug orally in a form from which it is most available for GI absorption. Several $investigation^{1-15)}$ demonstrated that the formation of solid dispersions or coprecipitates of relatively water-insoluble drugs with various pharmacologically inert carriers can increase singnificantly their in vitro dissolution rates. However, little information is available in the literature related to the dissolution rate patterns of furosemide, a water-insoluble diurectices, with respect to the sort of copolymer and the ratio of coprecipitates as a function of time, respectively. The purpose of the present investigation was to ascertain, the general applicability of the copolymers to use fore more fast, enhanced dissolution techniques of furosemide. To accomplish the need for enhancement in the dissolution rate of furosemide, varying ratio coprecipitates with different water-soluble polymers, such as polyvinylpyrrolidone (PVP), polyethylene glycol 4000(PEG 4000), and polyethylene glycol 6000 (PEG 6000), were quantitatively studied by comparing their dissolution characteristics of furosemide. The dissolution patterns of pure furosemide, varying ratio furosemide-PVP coprecipitates, (1:2, 1:5, and 1:9(w/w)), furosemide-PEG 4000 coprecipitates (1:4, 1:9, and 1:19(w/w), furosemide-PEG 6000 coprecipitates(1:4, 1:9, and 1:19(w/w)), and the same ratio physical mixtures, respectively, were compared by the amount dissolved as a function of time.

• Journal of Pharmaceutical Investigation
• /
• v.19 no.3
• /
• pp.155-161
• /
• 1989

Coprecipitates of chlorpropamide (CPA)-sodium deoxycholate (DC-Na) were prepared at various ratios of CPA to the DC-Na. The X-ray diffraction and DSC measurements indicated that CPA in 1:1 and 1:3 w/w CPA-DC-Na coprecipitates did not exist in amorphous form, but the others were amorphous. The dissolution rate of CPA from the CPA-DC-Na coprecipitates increased in distilled water and KP V 2nd disintegration test fluid (pH 6.8), but decreased extremely in KP V 1st disintegration test fluid (pH 1.2). The dissolution rates of CPA-DC-Na coprecipitates were compared with those of CPA alone and CPA-DC-Na physical mixtures. Especially, it was found that the dissolution rate of CPA markedly increased in the case of 1:5 CPA-DC-Na coprecipitate. The concentration of CPA dissolved from CPA-DC-Na coprecipitate reached a plateau within 5-10 min, and thereafter gradually decreased, indicating that CPA released from the coprecipitate was recrystallized.

• Journal of Pharmaceutical Investigation
• /
• v.13 no.3
• /
• pp.100-103
• /
• 1983

Coprecipitates of sulpiride and polyethylene glycol (PEG) decrease the dissolution rate of sulpiride and the degree of decrease is reversely proportional to molecular size of PEG and proportional to increase of PEG ratios in coprecipitates. The physical mixtures of sulpiride and PEG increase the dissolution rate of sulpiride.

• Journal of Pharmaceutical Investigation
• /
• v.12 no.4
• /
• pp.145-152
• /
• 1982

Data from IR spectroscopy and X-ray diffractometry were used for the characterization of sulpiride polyethylene glycol coprecipitates related with polymorphism of sulpiride. Sulpiride Form II transformed to Form I during coprecipitating with polyethylene glycol and the transformation rate is increased in proportion to molecular size of polyethylene glycol and the content of polyethylene glycol in coprecipitate.

• Journal of Pharmaceutical Investigation
• /
• v.18 no.2
• /
• pp.43-47
• /
• 1988

In order to increase the dissolution characteristics of relatively water-insoluble metoclopramide (MCP), coprecipitates of MCP with polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) 1000, 4000 or 6000 were prepared in various drug to polymer ratios. The dissolution rate of MCP-PVP coprecipitate was greater than those of MCP alone, MCP-PVP physical mixture and MCP-PEG coprecipitates. The dissolution rate of MCP-PEG 6000 coprecipitate was greater than those of MCP-PEG 1000 and MCP-PEG 4000 coprecipitates. The dissolution half-lives $(T_{50%})$ for MCP alone and 1:5 (w/w) MCP-PEG 6000 coprecipitate were determined by the log-probit method at $37^{\circ}C$ and found to be 4.17 and 0.98 min, respectively.

• Journal of the Korean Ceramic Society
• /
• v.32 no.4
• /
• pp.455-461
• /
• 1995

To investigate the synthesis of $\beta$-Al2O3 and its crystallization behavior by oxalate coprecipitation method, the optimum pH range for oxalate coprecipitates has been theoretically calculated from the solubility products and the equilibrium constans of each metal ionic species and their solubility diagram wa obtained. The optimum pH range for oxalate coprecipitates at room temperature was estimated as <4. In experiment, we found that the optimum condition for oxalate coprecipitates was pH<1, which was not doped with pH controller. The Na+ ions were easily exchanged for the NH4+ ions of NH4OH which was used as pH controller, and those NH4+ ions were supposed to affect the crystallization behavior of $\beta$-Al2O3. The thermal decomposition of all complexes was almost complete below 40$0^{\circ}C$. The primary product of the decomposition process was m-Al2O3, which transformed to $\beta$"- or $\beta$-Al2O3 at temperature higher than 100$0^{\circ}C$. We found that the powder prepared at 120$0^{\circ}C$ had only $\beta$"- and $\beta$-Al2O3.EX>-Al2O3.

• Journal of Pharmaceutical Investigation
• /
• v.19 no.1
• /
• pp.1-7
• /
• 1989

Coprecipitates of ibuprofen (IPF)-sodium deoxycholate (DC-Na) were prepared at various mixing ratios of IPF to DC-Na. X-ray diffraction measurments indicated that IPF in 1:3 and 1:5 IPF-DC-Na coprecipitate did not exist in the crystal form, however in the 1:8 coprecipitate, IPF remained its crystalline form. The dissolution rate was tested in pH 7.4 phosphate buffer by the paddle method of dissolution test of KP V. The dissolution rates of IPF from 1:1, 1:3, 1:5, 1:8 and 1:10(w/w) IPF-DC-Na coprecipitates and physical mixtures were compared with that of IPF alone. It was found that the dissolution rate of 1:5(w/w) coprecipitate was greater than that of pure IPF, coprecipitate and physical mixture at any other ratios of the two components. The concentration of IPF released from the IPF-DC-Na coprecipitates reached a plateau within 10 min, and thereafter gradually decreased indicating that IPF released from the coprecipitate was recrystallized due to the transient supersaturation.

• Archives of Pharmacal Research
• /
• v.2 no.1
• /
• pp.49-64
• /
• 1979

In an atempt to elucidate further physicochemical properties of furosemide-PVP coprecipitates, extensive investigations such as TLC, UV,IR, NMR, X-ray diffraction, TGA and DTA studies were carried out for the furosemide test systems. X-ray diffraction studies revealed that the pure furosemide and the furosemide contained within a physical mixture were crystalline in nature. However, there was no crystallinity evident in the 1:5 furosemide-PVP 40,000 coprecipitate system, even after standing for two years. The various ratio furosemide-PVP 40,000 coprecipitate systems revealed that the coprecipitate containing a greater amount of PVP 40,000 than that of furosemide showed a crystalline state of furosemide and that the minimum amounts of PVP to make amorphous form of furosemide was 1:1 ratio of furosemide to PVP. From the furosemide-PVP coprecipitate systems with PVP of different molecular weights of 10,000, 40,000 and 360,000, all the 1:1 ratio coprecipitates did not exhibit any crystallinity of furosemide, whereas all the 2:1 ratio coprecipitates showed a presence of crystalline furosemide. All the coprecipitated preparations with PEG 4,000 and with PEG 6,000 showed the diffraction peaks indicating the presence of crystalline furosemide. The comparison of infrared spectra of the physical mixture and the coprecipitate showed an interaction such as association between the functional groups of furosemide and PVP in the molecular level, whereas the studies by TLC, UV and NMR showed its dissociation in methanol solution. The weight losses in TGA curves showed all the same patterns. However, a little different transition form in DTA thermograms was shown between the physical mixture and the coprecipitate, indicating the different thermal property.

• YAKHAK HOEJI
• /
• v.20 no.1
• /
• pp.6-11
• /
• 1976