• Archives of Pharmacal Research
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• v.12 no.2
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• pp.88-93
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• 1989

In order to obtain some informations about the effect of molecular weight on the release rate of drug from drug carrier, two types of poly-L-glutamic acid (PLGA)-cytarabine (ara-C) conjugates, PLGA-ara-C:I and PLGA-ara-C:II, were synthesized using two types of PLGA having different average molecular weight, 43,000 and 77,800, respectively. The PLGA-ara-C conjugates were synthesized by mixed anhydride method and found to be covalently linked. Both types of conjugates charged negatively at biological pH. The pH-dependent release rate of ara-C was observed in both cases, and the release rate was accelerated in basic, acidic conditions (the k values were 0.015 $day^{-1}$ at pH 7.0, 0.024 $day^{-1}$ at pH 5.0, and 0.059 $day^{-1}$ at pH 9.0 in the case of PLGA-ara-C:I) and in the presence of pretense. The time required for the release of 16.5% of ara-C from PLGA-ara-C:I were 8 hr and 144 hr in the presence and absence of protease, respectively. Although both types of conjugates showed similar drug substitution ratio, they showed different release rates. Between the two types of conjugates, PLGA-ara-C:II showed the faster release rate (0.030 vs 0.042 $day^{-1}$ in pH 7.4 phosphate buffer solution at $37^{\circ}C$) and the smaller activation energy for the release of drug (12.5 vs 7.7 Kcal/mol) than PLGA-ara-C:I. The characteristic effect of molecular weight on the release rates of PLGA-ara-C conjugates suggests that the drug release rate might be effectively controlled over a prolonged period of time by the combined use of the different types of PLGA-ara-C conjugates having different molecular weights.

• YAKHAK HOEJI
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• v.49 no.4
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• pp.255-259
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• 2005

Financial standing of National Health Insurance has been experiencing a grave deterioration during the last 4-5 years, and the yearly amount paid by the insurance for drug expense rose up to 4 trillion won recently. Furthermore, the ratio of drug expenses in the total expenditure of the insurance reached about $25\%$, showing the tendency to be levelled off. As a measure to improve the financial deterioration of the insurance and to encourage generic substitution among the health professionals, we compared pharmacokinetic parameters of brand name drug (Lamisil) and generic drug (Muzonal) containing terbinafine HCl in healthy volunteers. The area under the curve (AUC) of the two drugs showed $2220.4\pm784.7\;and\;2143.1\pm861.6hr{\cdot}ng/ml$ in the corresponding order and no statistically significant difference was identified. The peak concentration $(C_{max})$ of the generic drug demonstrated $566.6\pm246.2 ng/ml$ compared to $550.8\pm204.0$ of brand name drug, which was not significantly different either. Time to reach peak concentration showed about 6 minutes difference between the drugs, which has no clinical significance to the treatment of dermatomycosis and dermatophytosis.

• Macromolecular Research
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• v.12 no.1
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• pp.63-70
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• 2004

We have synthesized various types of poly(ethylene glycol) (PEG)-ibuprofen conjugates by the nucleophilic substitution of bromo-terminated PEG with ibuprofen-Cs salt; PN (Pluronic) was also used in place of PEG. All the bromo-terminated PEGs and PN were obtained in high yield. Conversions of the terminal hydroxyl groups to bromo-termini were quantitative, as were the drug conjugation processes. The Ι$_1$/Ι$_3$values obtained from solutions of the ibuprofen-conjugated prodrugs are summarized in relation to those of ibuprofen in water and in aqueous solutions of the original PEG, PN, and several ordinary surfactants. We believe that the fully hydrophilic PEG is completely hydrated and forms no hydrophobic pocket by segment aggregation. These results indicate that the probe environment is significantly hydrophobic, particularly in the solution of prodrug PN, for which the ratio is similar to that obtained from typical micelles of surfactants. The results suggest, therefore, that the present synthetic method is very useful for preparing PEG-based prodrugs from pharmaceuticals having carboxyl functionalities.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4035-4040
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• 2012

Presented study describes the synthesis of photo cross-linkable and water soluble hydroxyethyl starch hydroxyethyl methacrylate (HESHEMA) samples with different degree of substitution (DS) by functionalization of hydroxyethyl starch (HES) with hydroxyethyl methacrylate (HEMA) or hydroxyethyl methacrylate carbonylimidazole (HEMACI) in DMSO using two different routes. It was revealed that the reaction time for HESHEMA synthesis can be reduced from 5 days to 24 h by conducting the reaction at $80^{\circ}C$ instead of at room temperature. Solubility of HESHEMA was found to be dependent on DS which in turn was dependent on ratio between HES and HEMA or HEMACI. HESHEMA samples with DS > 0.24 depicted insoluble in water, whereas the samples with DS < 0.05 did not form appreciable gel. HESHEMA samples with appropriate DS were converted into hydrogels by cross-linking polymer chains under UV radiations and resulting HESHEMA hydrogels showed swelling up to 1200%. Application of HESHEMA in controlled drug delivery was investigated by diffusion based encapsulation of Ondansetron, a serotonin 5-$HT_3$ receptor antagonist drug, mainly used for nausea and vomiting treatment.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.237-242
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• 1989

The physical properties and drug release behaviours of polyethylene glycol grafted poly ${\gamma}$- benzyl L-glutamate (PEG- g- PBLG), polyethylene glycol crosslinked poly ${\gamma}$-benzyl L- glutamate(PEG-c-PBLG), and PBLG homopolymer are compared. PBLG containing PEG segements showed higher wettability and larger enlongation than PBLG homoplymer, but lower elastic modulus. The release rate of rhodamine is strongly influenced by the wettability of the polymer. Rhodamine is more rapidly released from PEG-c-PBLG membrane having a larger water contact angle than from other polymer having a lower water contact angle. The surfaces of PBLG derivative membranes are modified by substitution reaction using hydroxyalkylamine. The resulting polymer membranes showed hider wettability and swelling ratio than virgin membranes.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.507-528
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• 2011

Agricultural workers who mix/loads and spray pesticide in fields expose to pesticide through dermal and inhalation routes. In such situation, exposed amount should be measured quantitatively for reasonable risk assessment. Patch, gloves, socks and mask will be good materials for monitoring for dermal exposure while personal air monitor equipped with solid adsorbent and air pump will be a tool for inhalation exposure. For extrapolation of absorbed amount in dermal exposure matrices and of trapped amount in solid sorbent to total deraml or inhalation exposure, Korean standard body surface area and respiration rate were proposed in substitution of EPA data. Important exposure factors such as clothing and skin penetration ratio of dermal and inhalation exposure were suggested based on Spraying time for exposure monitoring must be long enough that the amount of pesticide to get absorbed/trapped in exposure matrices results in reasonable analytical value. In domestic case for the both of speed sprayer and power spray machine, spraying time of 20~40 minutes (0.1~0.2 ha) will be reasonable per single replicate before extrapolating to 4 hours a day with triplicates experiment.