Sp ecial issue on“Form ulation strategies and m anufacturing technologies to enhance non-invasive drug delivery”

Oral dosage forms including tablets and capsules are the m ost com m only used drug products.For som e poorly w atersoluble and poorly perm eable drugs injectable dosage form s can be used to circum vent the challenges of poor bioavailability.However,injectable dosage form s are not alw ays preferred and m ay in the w orst case exert lim itations on patient compliance for exam ple needle pain,needle fear,or needle stick injuries.Furtherm ore,they often require health care professionals for the adm inistration.Developm ent of non-invasive drug delivery system s such as pulm onary,ocular,and transderm al delivery have been an intensive research area in the f ield of pharm aceutical sciences,w hich can exert both topical and system ic pharm acological effects.In addition,novel form ulation technologies are continuously evolved to enhance the oral bioavailability of drugs w ith poor physicochem ical properties.

The contributions in this special issue ref lect the w ide interest in enhancing non-invasive drug delivery by using various form ulation strategies and m anufacturing technologies.The special issue consists of one review and nine research articles.It starts w ith a review article focusing on the research and developm ent of alternative delivery strategies for apom orphine,aim ing to highlight the potential of non-invasive apom orphine delivery for the treatment of Parkinson’s disease for instance via the sublingual and transderm al adm inistration routes[1].The f irst tw o research papers in the special issue focus on transderm al delivery and ocular delivery,respectively.Lu et al.used nanocrystal technology to improve transderm al delivery of m eloxicam,w here the preparation,in vitro and in vivo evaluation of the form ulations w ere reported[2].To im prove the corneal perm eability of the poorly w atersoluble drug,disulf iram,for the treatm ent of cataract,Jiang et al.form ulated the drug into a therm osensitive in-situ gel based on a solid dispersion[3].The subsequent three research articles in the special issue report on the feasibility of a selfnanoem ulsif iying drug delivery system[4],am orphous solid dispersions[5],and a pro-drug strategy[6]to enhance oral bioavailability of a lipophilic drug,a hydrophobic drug,and a polar drug,respectively.Continuing w ith oral dosage form s,the sixth research paper show cases a m atrix tablet formulation strategy for sustained-release of a highly water-soluble drug[7].The seventh and eighth research papers report on the transfer of form ulation strategies into m anufacturing.Bohr et al.reported critical effects of solvent com position on the quality attributes of electrosprayed polymeric microparticles[8],and the study by Rantanen et al.dem onstrated that 3D printing could be used for prototyping of both parts of production line and PAT interfacing solution[9].In the last research paper of this special issue,Rosenholm et al.present that surfacem odif ied m esoporous silica nanoparticles could be considered as prospective vectors for therapeutic siRNA delivery[10].

The guest editors w ish to take this opportunity to thank the review ers for their valuable com m ents and constructive suggestions.We are also grateful to all the authors for the excellent contributions and great support,m aking this special issue possible.We hope this special issue w ill be of interest to m any readers.

Korbinian Löbm ann

Adam Bohr

Mingshi Yang