In medicine, adjuvants are agents which modify the effect of other agents while having few if any direct effects when given by themselves. In this sense, they are very roughly analogous with chemical catalysts.

Pharmacology

In pharmacology, adjuvants are drugs that have few or no pharmacological effects by themselves, but may increase the efficacy or potency of other drugs when given at the same time.

For instance, caffeine has minimal analgesic effect on its own, but may have an adjuvant effect when given with paracetamol.

Immunology

Similarly, in immunology an adjuvant is an agent which, while not having any specific antigenic effect in itself, may stimulate the immune system, increasing the response to a vaccine. The compound QS21 is under investigation as a possible immunological adjuvant.

Oncology

The terms adjuvant and neoadjuvant have special meanings in oncology. Adjuvant therapy refers to additional treatment given after a main mode of therapy, which is usually surgery. For example, radiotherapy or chemotherapy given after surgery for a breast cancer are both considered adjuvant treatments.

Neoadjuvant therapy, in contrast to adjuvant therapy, is given before the main treatment. For example, chemotherapy that is given before removal of a breast is considered neoadjuvant chemotherapy.

When radiotherapy is used as the main mode of treatment, the terms adjuvant and neoadjuvant refer to any additional treatment (usually chemotherapy) given before or after radiotherapy, respectively.

See also

• Freund's Complete Adjuvant
• Medication
• Drug synergism