Excipients are substances added to drug or vaccine in order to make into an actual pill for administration. Besides the active vaccine itself, several excipients exist that are incorporated into the vaccine during their development. And these excipients include antibiotics, formaldehyde, aluminium gels or salts and preservatives amongst others.
- Aluminium salts or gels are added as adjuvants. Adjuvants are added to promote or enhance the immune response to the vaccine thereby allowing for a lower vaccine dosage.
- Antibiotics are also added to some vaccines to prevent the growth of bacteria during the production and storage of the vaccine.
- Formaldehyde is usually added to inactivate bacterial products for toxoid vaccines. It is also used to inactivate unwanted viruses that might contaminate the vaccine during production.
- Monosodium glutamate (MSG) and 2- phenoxy ethanol are used as stabilizers in a few vaccines to help the vaccine remain unchanged even when exposed to heat, light, acidity or humidity.
- Thiomersal is an antiseptic and an antifungal agent containing mercury that acts as a preservative in vaccines. It is usually added to the vials and/or phials of vaccine that contains more than one dose. The essence of adding these substances is for no other reason other than to prevent the contamination and growth of potentially harmful organisms in the vaccines. But due to the concerns of mercury poisoning, thiomersal is no longer used as a preservative in vaccines especially in childhood vaccines. Thiomersal is still a component of tetanus shots.
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