Types of Adverse Drug Reactions (ADR)

Type A

1. Type A reactions are extensions of the drug’s known pharmacology and are responsible for the majority of ADRs.
2. Type A reactions are usually dose dependent and predictable but can be the result of concomitant disease states, drug–drug interactions, or drug–food interactions.
3. Ways to minimize type A reactions include understanding the pharmacology of the drug being prescribed, monitoring drugs with a narrow therapeutic index, and avoiding polypharmacy when possible.

Type B

1. Type B reactions include idiosyncratic reactions, immunological or allergic reactions, and carcinogenic/teratogenic reactions.
2. Type B reactions are usually not the result of a known pharmacology of the drug but seem to be a function of patient susceptibility. They are rarely predictable, are usually not dose dependent, and seem to concentrate in certain body systems such as the liver, blood, skin, kidney, and nervous system.
3. Type B reactions are uncommon but are generally serious and can be life threatening.
4. Except for immediate hypersensitivity reactions, type B reactions may take as long as 5 days before the patient demonstrates hypersensitivity to a drug. There is no maximum time for the occurrence of a reaction, but most occur within 12 weeks of initiation of therapy.

What Should be Reported in Adverse Drug Reactions?

1. ADRs that are serious, even if causality is not proven, including:
   • A patient’s death that is suspected of being a direct outcome of an ADR
   • A life-threatening event
   • An initial or prolonged hospitalization
   • A significant, persistent, or permanent change or disability/incapacity
   • A congenital anomaly (including those occurring in a fetus)
   • Other problems that are not listed in the manufacturer’s package insert as a known side effect, especially those that may jeopardize the patient and require medical or surgical intervention.
2. Product problems that can result in compromised safety or quality, including product contamination, mislabeling, unclear labeling, poor packaging, potency problems, and questionable stability
3. Counterfeit or suspected counterfeit drugs
4. Adverse events owing to blood products, allergenics, gene therapy, human tissue and cellular products, and xenotransplantation products
5. Medication errors
6. Adverse events with food, herbs, vitamins, cosmetics, or dietary supplements, although CAERS is the preferred reporting system
7. Malfunctioning medical devices such as heart valves, latex gloves, dialysis machines, and ventilators and problems with nutritional products or use of a medical product that required surgical or medical intervention to prevent permanent damage to a body function or structure.

Read also:

• Pregnancy Categories Based on FDA and TGA
• Tips for Effective Pharmacovigilance Reporting of Adverse Events