Butyl vs Octyl

The shorter-chain derivatives tend to have a higher degree of tissue toxicity than the longer-chain derivatives.

Inflammation, tissue necrosis, granulation formation, and wound breakdown can occur when cyanoacrylates are implanted subcutaneously. The process causing the histologic toxicity is thought to be related to the by-products of degradation, cyanoacetate and formaldehyde. The local concentrations of these breakdown products are proportional to the rate of degradation (an aqueous degradation process) of the parent compound. Therefore, slower degradation rates result in less toxicity to the tissues. This is explained by the hypothetical possibility that slowly degrading compounds release degradation products more gradually, thereby permitting more effective clearance and invoking a less intense inflammatory response. The longer-chain compounds degrade much more slowly than the shorter-chain compounds, hence the lower reactivity of the longer-chain compounds.

Until recently, butyl-2-cyanoacrylate was the only commercially available cyanoacrylate tissue adhesive. Although butyl-2-cyanoacrylate is effective in closing superficial lacerations under low tension, it has several limitations. Several studies have shown wound-breaking strength in wounds repaired with butyl-2-cyanoacrylate to be equal to that in wounds repaired with sutures at 5-7 days; however, on day 1, breaking strength with the tissue adhesive is only approximately 10-15% of that in a wound sutured with 5-0 monofilament. After polymerizing, the adhesive becomes brittle and is subject to fracturing when used in skin creases or long incisions. This restricts the use of adhesives to areas of low tension, thus limiting their use for incision repair. Butyl-2-cyanoacrylate has been used widely with good cosmetic outcomes for various plastic surgical procedures (eg, upper lid blepharoplasty, facial skin closure, scalp wound closure).

The polymer 2-octyl cyanoacrylate was formulated to correct some of the deficiencies of the shorter-chain cyanoacrylate derivatives. As an 8-carbon alkyl derivative, this polymer should be less reactive than the shorter-chain derivatives. The slower degradation of the octyl derivatives may result in lower concentrations of the cyanoacrylate polymer by-products in surrounding tissues, resulting in less inflammation. Additionally, plasticizers are added to produce a more pliable and tissue-compatible product that flexes with the skin and remains inherent for longer periods of time. The 3-dimensional breaking strength of 2-octyl cyanoacrylate is 4 times that of butyl-2-cyanoacrylate and is closer to that of a 5-0 monofilament suture. This stronger flexible bond may allow its use on longer incisions.

The Food and Drug Administration (FDA) has approved 2-octyl cyanoacrylate for closure of incised skin. In addition to its surgical adhesive indication, 2-octyl cyanoacrylate was approved by the FDA in January 2001 for use as a barrier against common bacterial microbes including certain staphylococci.