Pharmacovigilance is the study of problems associated with medication use, including allergies, adverse drug interactions, and other issues that may arise in patients taking prescription medications, herbal preparations, and other drugs. Most nations have programs in place to monitor such reactions and use layers of security to protect patient safety and identify concerns with individual drugs quickly, allowing regulators to take prompt action. Everyone from patients to researchers plays a role in pharmacovigilance around the world.
The first level of pharmacovigilance takes place early in drug development, as companies conduct a series of tests to make sure a drug is safe for use. In clinical trials, limited numbers of patients take the drug in controlled conditions, allowing doctors to monitor for allergies, side effects, and other problems. Clinical trials may indicate that a drug is not safe for use, and the company will decide not to move forward with an application for approval. In other cases, the drug appears safe, and it can be marketed and sold.
Commonly, problems with a drug appear after it hits the market. This happens because more people are taking the medication, increasing the chances of an adverse reaction as patients with different conditions use the medication, and as doctors prescribe it in combination with other drugs. Doctors participate in pharmacovigilance by reporting adverse reactions, using central databases. Patients can also file reports if they feel unwell while taking a drug.
Drug companies and regulators review these databases. If enough reports of similar problems start to appear, a recommendation may be made to further study the situation, with the goal of determining if new safety labeling is needed. Sometimes, the outcome of a pharmacovigilance investigation is a decision to take a drug off the market because it is too dangerous, or to restrict access to certain patients who meet a precise series of criteria, in cases where a drug is critical for the treatment of disease and there are no available alternatives.
Safety controls for medication also include regularly inspecting production facilities, testing batches of drugs, and using other pharmacovigilance tools to control quality in pharmaceutical companies. With things like herbal preparations, this can be challenging, as these drugs are not consistent, and it is hard to set quality control standards. People can investigate for impurities like dangerous herbs mixed in with a batch, but it is harder to make statements about the reliability and efficacy of these medications.