Classification of ADRS
ADRS were originally classified into two subtypes
Type A ADRS are dose-dependent and predictable, they are augmentations of known pharmacologic effects of the drug, such as orthostatic hypotension with antihypertensive medications.
Type B ADRs are uncommon unpredictable, depending on and the known pharmacology of the drug; they are independent. of dose and affect a small population, suggesting that individual patient host factors are important. Hypersensitivity (allergic) reactions to drugs are examples of type B ADRS.
Type A reactions were later called augmented, and type B reactions, bizarre. Two further types of reactions were eventually added: chronic reactions, which relates to both dose and time (type C), and delayed reactions (type D). Withdrawal later became the fifth category (type E), and most recently, unexpected failure of therapy became the sixth (type F).
About 80% of ADRs in the hospital setting or causing admission to a hospital are type A These ADRS are potentially avoidable and often predictable. The drug classes most commonly responsible for ADRS in adults are adrenal corticosteroids, antibiotics, anticoagulants, anti neoplastic and immunosuppressive drugs, cardiovascular drugs, non steroidal anti inflammatory drugs, and opiates. For children,the most prevalent drug classes for ADRs are anti-infective drugs, respiratory drugs, and vaccines.
Identification of ADRS
In both the inpatient and outpatient setting, a patient’s new or worsening symptoms a may be the first sign of an ADR. In a community pharmacy, patients often seek advice from the pharmacist to treat various symptoms at home.
This can be an opportunity for the pharmacist to inquire about the patient’s symptoms to determine whether they might have been caused by an ADR.
For example, if a patient asks the pharmacist for a recommendation to treat diarrhea, the pharmacist could inquire about other medications the patient is taking to determine whether diarrhea is a known ADR associated with the drug therapy, such as with antibiotics.
An over-the-counter (OTC) medication may not be needed, and the diarrhea may resolve on completion of the antibiotic therapy. In the inpatient setting. patients may tell their nurse or physician about the new symptom they are having, which may result in a telephone call to the pharmacist. Asking detailed questions about the patient’s symptoms, rather than immediately providing a treatment recommendation, could uncover an ADR and prevent unnecessary drug therapy or further ADR symptoms. Noticing that an atypical laboratory or diagnostic procedure has been ordered may indicate that an ADR has occurred. Common laboratory tests can also assist in identifying an ADR. A new order for a serum drug level may alert the practitioner to investigate whether an ADR caused by drug toxicity or treatment failure is occurring. Laboratory monitoring can help determine improvement or decline after a change in therapy.
