Preparation and release mechanism of gestodene reservoir-type intravaginal rings / 药学学报

This study taking gestodene (GEST) as a model, investigated the factors affecting reservoir-type intravaginal ring (IVR)'s drug release. This paper reported a gestodene intravaginal ring of reservoir design, comprising a gestodene silicone elastomer core encased in a non-medicated silicone sheath, separately manufactured by reaction injection moulding at 80 degrees C and heating vulcanization at 130 degrees C is reported. The test investigated the factors affecting drug release through a single variable method, taking the drug release rates of 21 days as standards. When changing the thickness of the controlling sheath outside, the ratio of the first day of drug release and mean daily release (MDR), named the relatively burst effect, is closing to 1 with the thickness of controlling sheath increasing, while the 1.25 mm sheath corresponding to 1.04 controlled the burst release effectively; a positive correlation (r = 0.992 2) existed between the average drug release (Q/t) and drug loading (A) within a certain range. The C6-165 controlling sheath with high solubility of GEST is easier to achieve controlled release of the drug; GEST crystalline power is more effective to implement controlled release of drugs among difficent states of the drug. A 1/4 fractional segment core gives a relatively burst effect of 1.76, while the 1/1 and 1/2 are 1.93 and 1.87 separately, at the same drug loading, concluding that use of a fractional segment core would allow development of a suitable GEST reservoir IVR. In summary, GEST reservoir-type IVR could be adjusted by the thickness of controlling sheath, the loading of drug, the material properties of controlling sheath, the dispersion state of drug, the additive composition and structure of intravaginal ring, to control the drug release behavior and achieve the desired drug release rate.

Study of the interactions between diorganotin (IV) complexes of 1,3-dimethyl-4-acetyl-5-pyrazolone and mononucleotides and DNA / 药学学报

<p><b>AIM</b>The interactions between diorganotin (IV) complexes of 1,3-dimethyl-4-acetyl-5-pyrazolone (HL1) and mono-nucleotides together with DNA near physiological condition were investigated.</p><p><b>METHODS</b>The mode of action of the diorganotin (IV) complexes with mononucleotides and DNA under different conditions and different times were investigated by high resolution NMR technology and UV spectra.</p><p><b>RESULTS</b>The interaction of [(L1)2SnEt2] with AMP was shown to result in significant change of chemical shift of H(8), H(2) and 31P of AMP. Hyperchromic effect of DNA could be observed due to the interaction of; [(L1)2SnEt2] with DNA, while interaction of [(L1)2SnMe2] with AMP and DNA could only cause obvious change of chemical shift of 31P and lead to hypochromic effect of DNA.</p><p><b>CONCLUSION</b>The results indicate that [(L1)2SnEt2] can selectively bind to the N1 atom of the base and the phosphate oxygen atom of AMP and may further destroy the helical structure of DNA, while the dimethyltin (IV) compound of 1,3-dimethyl-4-acetyl-5-pyrazolone [(L1)2SnMe2] merely binds to the the phosphate oxygen atom of AMP and causes the contraction of DNA helical structure.</p>