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Dextran conjugation has aided the design of new tailor-made polymers with different molecular weights, shapes, structures and with the functional groups needed for coupling at the desired positions in the chain. Dextran prodrugs are very useful systems for achieving controlled drug release and drug targeting. In particular, various dextran-antitumor drug conjugates enhance the effectiveness and improve the cytotoxic effects of chemotherapeutic agents. Future studies should concentrate on barriers for their clinical use and safety as a drug carrier.

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The objective of this work was to develop matrix sustainedrelease tablets of highly water-soluble tramadol HCl using natural gums (xanthan [X gum] and guar [G gum]) as costeffective, nontoxic, easily available, and suitable hydrophilic matrix systems compared with the extensively investigated hydrophilic matrices (ie, hydroxypropyl methylcellulose [HPMC]/carboxymethyl cellulose [CMC] with respect to in vitro drug release rate) and hydration rate of the polymers. Matrix tablets of tramadol (dose 100 mg) were produced by direct compression method. Different ratios of 100:0, 80:20, 60:40, 20:80, 0:100 of G gum (or X):HPMC, X gum:G gum, and triple mixture of these polymers (G gum, X gum, HPMC) were applied. After evaluation of physical characteristics of tablets, the dissolution test was performed in the phosphate buffer media (pH 7.4) up to 8 hours. Tablets with only X had the highest mean dissolution time (MDT), the least dissolution efficiency (DE 8 %), and released the drug following a zero-order model via swelling, diffusion, and erosion mechanisms. Guar gum alone could not efficiently control the drug release, while X and all combinations of natural gums with HPMC could retard tramadol HCl release. However, according to the similarity factor ( f 2 ), pure HPMC and H 8 G 2 were the most similar formulations to Topalgic-LP as the reference standard.

In the present study, cholesterol nanostructured lipid carriers with various oleic acid content loaded with paclitaxel (PTX) were prepared by solvent emulsification-diffusion method using a Taguchi design. Size, zeta potential, entrapment efficiency, drug loading, and release percent of NLCs were measured. The results indicated that the most effective factors on the size were oleic acid content and surfactant percent. Zeta potential was more affected by the drug content. Drug to-lipid weight ratio was the most effective factor on entrapment efficiency and drug release from NLC. In the present work, the effect of lyophilization on the particle size and release properties of NLCs was also evaluated. The results revealed no differences between the characteristics of NLCs before and after freeze drying by using 25% w/w sorbitol as cryoprotectant. Cytotoxicity studies indicate that PTX associated with the NLC is also effective in HT-29 cell lines and enters the cancer cells selectively through the LDL receptor endocytic pathway. The IC 50 values of free PTX solubilized in Cremophor EL and NLC-born PTX after 72 h exposure were 8.32 ± 1.35 ng/mL and 5.24 ± 0.96 ng/mL, respectively.