Pharmaceuticals and Medical Devices

In the field of dental treatment, alginate is used as a base for tooth-moulding preparations (dental impressions), commonly referred to as alginate impression agent.

Dental impressions, a mix of alginate, calcium salts, phosphate and diatomaceous earth, are well established formulations. When mixed with water, the alginate and calcium gelation begins. The reaction time is controlled by phosphate, and gelation is completed in a short time when pressed against the teeth. Alginate impression agents are widely used in dental treatment settings both in Japan and worldwide due to their relatively inexpensive nature, ease of operation (low failure level), ease of use and being able to accurately capture detailed impressions.

Drugs treating peptic ulcer disease use the properties of alginate which gel under acidic conditions. The ingredient of this oral drug is just an aqueous solution of alginate. When an aqueous alginate solution comes into contact with stomach acid, it becomes insoluble and covers the entire wall of the stomach. If the lining of the stomach is damaged, alginate may react with iron and calcium in the blood to gel over the bleeding area, relieving the attack of stomach acid on the wound and relieving pain. This medicine has been prescribed for many years as a mild oral medication with fewer side effects and less harm to patients.

Drugs that combine an aqueous solution of alginate with an antacid and a raft-forming agent are gaining popularity worldwide. When taken, excess stomach acid is suppressed and insoluble alginate in stomach acid forms a floatable raft that blocks the upper part of the stomach and prevents reflux of the contents. As a result, the symptoms of heartburn and stomach bloating are relieved.

A hard tablet is moderately disintegrated in the digestive tract and an aid that helps release the active ingredient is called a disintegrant. Powders such as starch are commonly used as disintegrants as they absorb moisture and swell in the stomach after swallowing, thereby disintegrating the tablets (releasing the active ingredients).

Alginate is insoluble under acidic conditions and soluble under alkaline conditions. Therefore, when alginate is incorporated as a disintegrant, alginate in tablets does not swell in the stomach (acidic), but swells when it enters the high pH gastrointestinal tract, causing the tablets to disintegrate (releasing medicinal ingredients). Thus, alginate can be used to control the timing of release of medicinal ingredients.

Eye drops containing alginate may thicken in response to trace amounts of calcium in tears after application. As a result, it is possible to prolong the time for the active ingredient to reside on the ocular surface. As the retention time of the eye drops increases, the concentration of the eye drops can be lowered, thus reducing irritation caused by the drug. It also reduces the patient's stress by reducing the number of eye drop applications.
If the eye drops themselves are viscous from the start, they are uncomfortable, leaving a sticky feeling over the entire eye. The properties of alginate that make it viscous at the time of instillation are valuable in developing eye drops that are easier to use.

In the past, experience said that it was better to dry the wound (wound surface) and treat the wound by forming a scab. Recently, however, it has become the mainstream practice to maintain the wet state without drying the wound surface as much as possible.
Wound dressings that maintain the wet condition of the wound surface are made from fibers or sponges of alginate.
Alginate-based wound dressings become swollen and jelly-like on the contact surface from the fluid which exudes from the surface of the wound. This helps maintain a wet condition, makes it less painful when the dressing is removed and it does not damage the wound surface. It is used to treat a wide range of wounds, such as pressure sores.

In endoscopic examination and treatment of early-stage gastrointestinal cancer, a local injection (medical device) is injected into the submucosa between the lesion and the muscularis layer. The lesion is lifted (artificially raised) and removed from each mucosa. Low endotoxin alginate is used as the main material for this medical device. Hyaluronic acid has been used in existing products for the same purpose. However, there are concerns about the safety of animal-derived raw materials and the focus is moving to plant-based alginates.

In the field of regenerative medicine, research and development is also underway, focusing on the unique properties of alginate. Alginate’s unique physical properties, which change from solution to gel without heating or cooling, enable locally injecting alginate into any location before gelling, or suspending or gelling living tissue in vivo. This property has been applied to scaffolds for tissue regeneration and to substrates for 3D bioprinters.

Other biomaterials used in regenerative medicine often include collagen and hyaluronic acid but animal-derived materials can cause biological reactions when introduced into the body. Alginate from seaweeds, on the other hand, has been shown to have no such reaction and is slowly degraded in the body. "No effect even when administered to living organisms" is a major feature of alginate as a biomaterial.