Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Skin Res Technol. 2012 Nov;18(4):447-55. doi: 10.1111/j.1600-0846.2011.00592.x. Epub 2012 Jan 11.
Thinner and shorter needles for subcutaneous administration are continuously developed. Previous studies have shown that a thinner needle causes fewer occurrences of painful needle insertions and that a shorter needle decreases the occurrence of painful intramuscular injections. However, little is known about local drug delivery in relation to needle length and thickness. This study aimed to compare deposition depth and backflow from three hypodermic needles of 3 mm 34G (0.19 mm), 5 mm 32G (0.23 mm), and 8 mm 30G (0.30 mm) in length and thickness.
Ex vivo experiments were carried out on pigs, in neck tissue comparable to human skin at typical injection sites. Six pigs were included and a total of 72 randomized injections were given, i.e. 24 subcutaneous injections given with each needle type. Accordingly, 400 μL was injected including 70% NovoRapid(®) (Novo Nordisk A/S, Bagsvμrd, Denmark) and 30% Xenetix(®) (Guerbet, Villepinte, France) contrast including 1 mg/mL Alcian blue. Surgical biopsies of injection sites were sampled and computer topographic (CT)-scanned in 3D to assess deposition and local distribution. Biopsies were prepared and stained to evaluate deposition in comparison to the CT-scanning findings. The backflow of each injection was collected with filter paper. The blue stains of filter paper were digitized and volume estimated by software calculation vs. control staining.
CT-scanning (n = 57) and histology (n = 10) showed that, regardless of injection depth, the bulk of the injection was in the subcutaneous tissue and did not propagate from subcutis into dermis. With the 8 mm 30G needle all injections apart from one intramuscular injection were located in the subcutaneous layer. The volume depositions peaked in 4-5 mm depth for the 3 mm 34G needle, in 5-6 mm depth for the 5 mm 32G needle, and in 9-10 mm depth for the 8 mm 30G needle. In general, injection depositions evaluated by histology and CT-scans compared well for the individual biopsies. The amount of backflow (n = 69) from the 3 mm 34G needle was smaller (P < 0.05) as compared to the 5 mm 32G and the 8 mm 30G needles. Analysis showed a correlation between backflow and the needle's outer dimension with the needle diameter being the pivotal parameter. Furthermore, CT-scanning and histology confirmed that local propagation of the injection and final distribution followed a route of less mechanical resistance as determined by connective tissue barriers preset in the site of injection.
Needles as short as 3 mm efficiently delivered injections into the subcutaneous target. The amount of backflow was smaller with thinner needles. Local distribution was variable and determined by mechanical barriers preset in the tissue. CT-scans and histology were concordant.
皮下给药的更细、更短的针不断被开发出来。之前的研究表明，更细的针会导致更少的疼痛针插入，更短的针会减少疼痛的肌肉注射。然而，关于针的长度和厚度与局部药物输送的关系知之甚少。本研究旨在比较三种皮下注射针（3 毫米 34G（0.19 毫米）、5 毫米 32G（0.23 毫米）和 8 毫米 30G（0.30 毫米））的注射深度和回流情况。
在颈部组织上进行了离体猪实验，颈部组织与人体皮肤在典型注射部位相似。纳入了 6 头猪，总共进行了 72 次随机注射，即每种针型注射 24 次。因此，共注射了 400 μL 药物，包括 70%诺和锐®（丹麦诺和诺德公司）和 30% Xenetix®（法国盖尔伯特公司）造影剂，造影剂含有 1mg/mL 阿利新蓝。注射部位的手术活检标本用计算机断层扫描（CT）进行 3D 扫描，以评估沉积和局部分布。对活检标本进行处理和染色，以评估与 CT 扫描结果的沉积情况。用滤纸收集每次注射的回流液，用软件计算与对照染色相比，滤纸的蓝色染色的数字化和体积估计。
CT 扫描（n = 57）和组织学（n = 10）显示，无论注射深度如何，大部分注射药物都位于皮下组织，不会从皮下组织传播到真皮。使用 8 毫米 30G 针，除了一次肌肉内注射外，所有注射均位于皮下层。对于 3 毫米 34G 针，注射药物的沉积峰值出现在 4-5 毫米深度，对于 5 毫米 32G 针，出现在 5-6 毫米深度，对于 8 毫米 30G 针，出现在 9-10 毫米深度。一般来说，组织学和 CT 扫描对单个活检标本的注射药物沉积评估结果较好。与 5 毫米 32G 和 8 毫米 30G 针相比，3 毫米 34G 针的回流量（n = 69）较小（P < 0.05）。分析表明，回流与针的外径有关，其中针直径是关键参数。此外，CT 扫描和组织学证实，注射的局部传播和最终分布遵循组织内预先设定的机械阻力较小的途径。
最短 3 毫米的针可有效地将注射药物注入皮下靶位。更细的针回流量更小。局部分布是可变的，由组织中预先设定的机械屏障决定。CT 扫描和组织学结果一致。
