Technology and product reviews
T E C H N O L O G Y U P D A T E : Rediscovering alginate dressings
Author: Michael Clark
It is approaching 30 years since the first commercially available alginate wound dressing was launched in 1983. This review revisits this group of wound dressings and traces their development, mode of action and use in clinical practice. The author concludes by posing questions about the future for alginate dressings and identifying unanswered questions related to their role in wound healing.
INTRODUCTION While the use of alginate wound dressings dates back 30 years there are anecdotal reports of the use of seaweed to treat wounds dating back to Roman times. In folklore seaweed was also said to have been used by sailors to stem blood loss and by doctors in 18th century Scotland to drain abdominal wall abscesses[1-2]
. While interesting,
these anecdotes are difficult to verify through primary sources. After the second world war, the use of alginate
dressings as haemostatic agents was reported both in vitro and in clinical studies. They were also used in wound healing, initially in surgical wounds then in accident and emergency departments, leading to a widespread use of alginate dressings in surgical specialities across 70 UK hospitals[1]
. References 1. Thomas, S. Surgical Dressings
and Wound Management. 2010; Medetec Publications, Cardiff.
2.Wolters Kluwer Health. Seaweed. Available at: http://www.drugs.
com/npp/
seaweed.html (accessed 11 March, 2012).
3.McHugh, DJ. Production, properties and uses of alginates.
Available at:
http://www.fao.org/ docrep/X5822E/
x5822e04.htm (accessed 11 March, 2012).
BACKGROUND Alginates are extracted from a variety of species of seaweeds, most notably: Laminaria (mainly harvested in Scotland, Ireland, Norway, France, China, Japan and North and South Korea)
Macrocystis (harvested in North America) Ascophyllum (harvested in inter-tidal areas in Scotland, Ireland and Canada)[3] The manufacture of alginates was first
.
described in the late 1800s, although commercial production began in the 1930s[2]
with alginates used for a wide variety of applications, including: Textile printing Food Paper
,
Welding rods Pharmaceuticals. However, no more than 4% of the
commercial production of alginates in the 1930s was used in wound healing[3]
. The adoption of alginate dressings was
effectively halted in the early 1970s when cheaper materials replaced alginate within the textile printing industry, thus making the limited use of alginates in healthcare commercially non-viable[1]
. An upsurge in the use of alginates in the
early 1980s arose through a growing interest in the treatment of acute and chronic wounds. Between 2011 and 2012 there were 19 different alginate dressings available in the UK[4]
.
MAKING ALGINATE DRESSINGS When alkaline is extracted from the seaweed and subsequently filtered, alginic acid is produced. Alginic acid is a linear polymer with two monomers (β-D-mannuronic acid and α-L-guluronic acid). The monomers are joined together in one of three chains: All β-D-mannuronic acid (M group) All α-L-guluronic acid (G group) Alternating units of β-D-mannuronic acid and α-L-guluronic acid (MG group) [3]
.
Different seaweeds give rise to varying ratios of M, G and MG groups within the alginic acid, with seasonal changes in the ratio of M to G groups also seen within species[3]
.
The alginic acid is then mixed, either with sodium carbonate or sodium hydroxide, to form sodium alginate. If this is forced under pressure through fine apertures into a solution
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Wounds International Vol 3 | Issue 2 | ©Wounds International 2012
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