Intratumoral delivery of chemotherapeutic agents may permit the localization of drugs in tumors, decrease nonspecific targeting and increase efficacy.

A novel microemulsion was prepared to increase the solubility and the in vitro transdermal delivery of poorly water-soluble vinpocetine. The correlation between the transdermal permeation rate and structural characteristics of vinpocetine microemulsion was investigated by pulsed field gradient nuclear magnetic resonance (PFG-NMR). For the microemulsions, oleic acid was chosen as oil phase, PEG-8 glyceryl caprylate/caprate (Labrasol) as surfactant (S), purified diethylene glycol monoethyl ether (Transcutol P) as cosurfactant (CoS), and the double-distilled water as water phase. Pseudo-ternary phase diagrams were constructed to obtain the concentration range of each component for the microemulsion formation. The effects of various oils and different weight ratios of surfactant to cosurfactant (S/CoS) on the solubility and permeation rate of vinpocetine were investigated. Self-diffusion coefficients were determined by PFG-NMR in order to investigate the influence of microemulsion composition with the equal drug concentration on their transdermal delivery. Finally, the microemulsion containing 1% vinpocetine was optimized with 4% oleic acid, 20.5% Labrasol, 20.5% Transcutol P, and 55% double-distilled water (w/w), in which drug solubility was about 3160-fold higher compared to that in water and the apparent permeation rate across the excised rat skin was 36.4 +/- 2.1 microg/cm2/h. The physicochemical properties of the optimized microemulsion were examined for the pH, viscosity, refractive index, conductivity, and particle size distribution. The microemulsion was stable after storing more than 12 months at 25 degrees C. The irritation study showed that the optimized microemulsion was a nonirritant transdermal delivery system.

Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS) and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All these dynamic properties of hydrogels have increased the interest in their use as a carrier for peptides and proteins to be released slowly in a sustained manner. Peptide and proteins are remarkable therapeutic agents in today’s world that allow the treatment of severe, chronic and life-threatening diseases, such as diabetes, rheumatoid arthritis, hepatitis. Despite few limitations, hydrogels provide fine tuning of proteins and peptides delivery with enormous impact in clinical medicine. Novels drug delivery systems composed of smart peptides and molecules have the ability to drive self-assembly and form hydrogels at physiological pH. These hydrogels are significantly important for biological and medical fields. The primary objective of this article is to review current issues concerned with the therapeutic peptides and proteins and impact of remarkable properties of hydrogels on these therapeutic agents. Different routes for pharmaceutical peptides and proteins and superiority over other drugs candidates are presented. Recent advances based on various approaches like self-assembly of peptides and small molecules to form novel hydrogels are also discussed. The article will also review the literature concerning the classification of hydrogels on a different basis, polymers used, “release mechanisms” their physical and chemical characteristics and diverse applications.

Traditional anti-tumor drugs still have some shortcomings, such as low solubility, poor selectivity and poor bioavailability, which decrease anti-tumor efficacy and aggravate systemic toxicity and side effects. In this paper,...

Conventional antitumor chemotherapeutics generally have shortcomings in terms of dissolubility, selectivity and drug action time, and it has been difficult to achieve high antitumor efficacy with single-drug therapy. At present, combination therapy with two or more drugs is widely used in the treatment of cancer, but a shortcoming is that the drugs do not reach the target at the same time, resulting in a reduction in efficacy. Therefore, it is necessary to design a carrier that can release two drugs at the same site. We designed an injectable pH-responsive OE peptide hydrogel as a carrier material for the antitumor drugs gemcitabine (GEM) and paclitaxel (PTX) that can release drugs at the tumor site simultaneously to achieve the antitumor effect. After determining the optimal gelation concentration of the OE polypeptide, we conducted an in vitro release study to prove its pH sensitivity. The release of PTX from the OE hydrogel in the medium at pH 5.8 and pH 7.4 was 96.90% and 38.98% in 7 days. The release of GEM from the OE hydrogel in media with pH of 5.8 and 7.4 was 99.99% and 99.63% in 3 days. Transmission electron microscopy (TEM) and circular dichroism (CD) experiments were used to observe the microstructure of the peptides. The circular dichroism of OE showed a single negative peak shape when under neutral conditions, indicating a β-folded structure, while under acidic conditions, it presented characteristics of a random coil. Rheological experiments were used to investigate the mechanical strength of this peptide hydrogel. Furthermore, the treatment effect of the drug-loaded peptide hydrogel was demonstrated through in vitro and in vivo experiments. The results show that the peptide hydrogels have different structures at different pH values and are highly sensitive to pH. They can reach the tumor site by injection and are induced by the tumor microenvironment to release antitumor drugs slowly and continuously. This biologically functional material has a promising future in drug delivery for combination drugs.