Transdermal Drug Delivery System of Linagliptin Sustained-release Microparticle Gels: In vitro Characterization and In vivo Evaluation.

BACKGROUND: Linagliptin (LNG) exhibits poor bioavailability and numerous side effects, significantly limiting its use. Transdermal drug delivery systems (TDDS) offer a potential solution to overcome the first-pass effect and gastrointestinal reactions associated with oral formulations. OBJECTIVE: The aim of this study was to develop LNG microparticle gels to enhance drug bioavailability and mitigate side effects. METHODS: Linagliptin hyaluronic acid (LNG-HA) microparticles were prepared by spray drying method and their formulation was optimized via a one-factor method. The solubility and release were investigated using the slurry method. LNG-HA microparticle gels were prepared and optimised using in vitro transdermal permeation assay. The hypoglycaemic effect of the LNG-HA microparticle gel was examined on diabetic mice. RESULTS: The results indicated that the LNG-HA microparticle encapsulation rate was 84.46%. Carbomer was selected as the gel matrix for the microparticle gels. Compared to the oral API, the microparticle gel formulation demonstrated a distinct biphasic release pattern. In the first 30 minutes, only 43.56% of the drug was released, followed by a gradual release. This indicates that the formulation achieved a slow-release effect from a dual reservoir system. Furthermore, pharmacodynamic studies revealed a sustained hypoglycemic effect lasting for 48 hours with the LNG microparticle gel formulation. CONCLUSION: These findings signify that the LNG microparticle gel holds significant clinical value for providing sustained release and justifies its practical application.

Study on the Nasal Drug Delivery System of NMD Liposomes In Situ Thermosensitive Gel.

Nimodipine (NMD) is a 1,4-dihydropyridine calcium antagonist that is effective in the prevention and treatment of cerebral arterial vasospasm and cerebral ischemic injury caused by subarachnoid hemorrhage. Since the drug itself is highly insoluble in water and has low oral bioavailability, while injectable formulations may cause pain and inflammation, the blood-brain barrier (BBB) prevents the effective delivery of therapeutic agents to the brain tissue. Therefore, in the present study, NMD liposomes were prepared by ethanol injection and innovatively lyophilised and loaded into temperature-sensitive in situ gels for intranasal administration as sprays to deliver drugs to brain tissues bypassing the blood-brain barrier. The optimal gel formulation was obtained by screening in which liposomes were divided into lecithin, cholesterol, and NMD in the ratio of 40:10: 1; Pluronic P407, Pluronic P188, Tween 80, polyvinyl ketone and ethyl nipagin in the ratio of (180:20:3:1:1); Pluronic P407, Pluronic P188, Tween 80, polyvinyl ketone, and ethyl nipagin in the ratio of (180:20:3:1:1). The prepared flow gel can form a solidified gel after a temperature of 31.07-32.07°C and a time of 58.51-59.89 s. Meanwhile, the NMD liposome gel formulation achieved sustained release over 56 h. The pharmacokinetic results of the developed NMD liposomal temperature-sensitive in situ gel and NMD temperature-sensitive in situ gel showed that liposomal nasal mucosal in situ gel is a more effective brain-targeted drug delivery system for NMD.

Intestinal transport mechanism of HA-LOR microspheres with different molecular weights in the MDCK cell model.

In this study, LOR microspheres with different molecular weights of hyaluronic acid (HA) were prepared by spray drying method using the second-generation antihistamine loratadine (LOR) as a model drug. A small intestinal transmembrane transport model was used to study the effect of HA molecular weight on small intestinal transmembrane transport and to explore the mechanism of HA molecular weight on intestinal absorption. The transmembrane transport of HA-LOR microspheres of different molecular weights was investigated by adding several inhibitors related to drug transmembrane transport and cellular function in the MDCK cell model. The results showed that low, medium and high molecular weight HA in HA-LOR microspheres had no effect on P-gp efflux and macrocytidine and had no effect on the transmembrane of LOR microspheres; medium molecular weight HA could affect Ca2+ channel and has an effect on the transmembrane transport of LOR microspheres; high molecular weight HA can affect clathrin-mediated endocytosis, lipid microcapsule-mediated endocytosis and endosomes, indicating that high molecular weight HA-LOR microspheres are effective in the intestinal tract. The uptake of LOR can be facilitated by the action of uptake enhancers, the action of Ca2+ channels and the uptake of ATP to LOR.

Synthesis and Antibacterial Activity Evaluation of Imidazole Derivatives Containing 6-Methylpyridine Moiety.

A series of 2-cyclopropyl-5-(5-(6-methylpyridin-2-yl)-2-substituted-1H-imidazol-4-yl)-6-phenylimidazo[2,1-b][1,3,4]thiadiazoles (15a-t and 16a-f) were synthesized and their antibacterial activities were evaluated. More than half of the compounds showed moderate or strong antibacterial activity. Among them, compounds 15t (MIC=1-2 µg/mL) and 16d (MIC=0.5 µg/mL) showed the strongest antibacterial activities. Notably, compound 16d did not exhibit cytotoxicity in HepG2 cells and did not show hemolysis like the positive control compound Gatifloxacin. The results suggest that compound 16d should be further investigated as a candidate antibacterial agent.

Study on the nasal drug delivery system of PPX microcapsules in situ thermosensitive gel.

Pramipexole hydrochloride (PPX) is a dopamine receptor agonist for the treatment of Parkinson's disease. It does not penetrate easily into the brain due to the presence of the blood-brain barrier (BBB), which hinders the treatment of the disease. The nasal mucosal drug delivery system is an effective method to deliver drugs to the brain bypassing the blood-brain barrier and the concentration of drugs targeted to the brain by intranasal administration is quite low due to the limitation of the permeability of the nasal mucosa and the nasal environment. Therefore, this study innovatively encapsulates prepared PPX microcapsules in a temperature-sensitive in situ gel for intranasal drug delivery to increase the target concentration of the drug in the brain and prolong the duration of treatment. The gel formulation containing 24% poloxamer 407 and 6% poloxamer 188 and 0.3% ice chips as absorption enhancers formed a hard gel at 30.44-31.36oC and allowed a slow release within 12 hours. A pharmacokinetic comparison of the developed PPX microencapsulated temperature-sensitive in situ gel (PPX-MTISG) with PPX temperature-sensitive in situ gel (PPX-TISG) revealed that the microencapsulated nasal mucosal in situ gel was a more effective PPX brain-targeted drug delivery system.

Preparation and Evaluation of a Microsponge Dermal Stratum Corneum Retention Drug Delivery System for Griseofulvin.

Griseofulvin (GF) is used as an antifungal to treat superficial skin fungal infections such as tinea capitis and tinea pedis. Currently, GF is only available in traditional oral dosage forms and suffers from poor and highly variable bioavailability, hepatotoxicity, and long duration of treatment. Therefore, the main objective of this study was to reduce the side effects of the drug and to increase the concentration of the drug retained in the cutaneous stratum corneum (SC) and improve its efficacy through the preparation of drug-laden GF microsponge (GFMS). The emulsification-solvent-diffusion method was used to prepare GFMS, and the prescriptions were screened by a single-factor approach. The optimized formulation (GFF8) had a microsponge particle size (µm) of 28.36 ± 0.26, an encapsulation efficiency (%) of 87.53 ± 1.07, a yield (%) of 86.58 ± 0.42, and drug release (%) from 77.57 ± 3.88. The optimized microsponge formulation was then loaded into a Carbopol 934 gel matrix and skin retention differences between the microsponge gel formulation and normal gels were examined by performing skin retention and fluorescence microscopy tests. Finally, the hepatoprotective and cutaneous stratum corneum retention abilities of microsponge gel formulations compared to oral GF formulations were assessed by hepatotoxicity, pharmacokinetics, and tissue distribution studies. This provides a new perspective on GF dermal stratum corneum retention administration.