The immune system has been called into service to help people who want to stop smoking. Vaccines offer the potential to block nicotine from crossing the blood brain barrier. This stops the reward from smoking, and has been effective in early clinical trials. There are three different vaccines under investigation at this time (March 2011):
1. NicVAX, from Nabi Pharmaceuticals
2. CYT002-NicQb (also called Nicotine-Qbeta or NIC-002), from Cytos Pharmaceutical
3. TA-NIC, from Celtic Pharma
Other pharmaceutical treatments for smoking include nicotine replacement products, general antidepressants such as bupropion (Zyban), and nicotinic receptor specific drugs such as varenicline (Chantix). Nicotine replacement products have demonstrated only modest success rates. Antidepressants and varenicline are somewhat more effective, but have serious side effects. The vaccine approach has four advantages, according to Reference 1:
1.The safety profile is better than that of most drugs.
2.Nicotine vaccines require only a brief series of monthly injections, instead of long-term daily pills.
3.The effects are relatively long-lived in clinical trials.
4.Vaccines have few interactions with other drugs, so they can be used in combination with anti-craving medication for individuals who have the most difficulty with smoking cessation.
For pregnant women, there is an added benefit that vaccines reduce fetal brain exposure to nicotine by 40 to 60 percent.
Vaccine development for drug abuse and dependence uses two approaches. Passive immunization is performed with monoclonal antibodies, similar to those in tumor necrosis factor inhibitor drugs, such as infliximab (used for rheumatoid arthritis and other autoimmune conditions). These offer immediate protection, and may someday be useful in saving lives from drug overdose. However, they are expensive and the effects are relatively short lasting. Active immunization is similar to what we expect from vaccines against the flu and other infectious diseases. It takes some time, ranging from weeks to months, to induce an active immune response.