Adverse drug reactions
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Adverse Drug Reactions: Definitions and Classification
Adverse drug reactions (ADRs) are harmful or unpleasant responses to medications that occur at normal doses used for prevention, diagnosis, or treatment of diseases. These reactions can predict future risks and may require changes in therapy, such as dose adjustment or discontinuation of the drug 1567. ADRs are distinct from adverse drug events, which are any negative occurrences after drug exposure, not necessarily caused by the drug itself 34.
ADRs are commonly classified into several types:
- Dose-related (Augmented): Linked to the amount of drug taken.
- Non-dose-related (Bizarre): Unpredictable and not related to dose.
- Dose and time-related (Chronic): Occur with prolonged use.
- Time-related (Delayed): Appear after some time.
- Withdrawal (End of use): Happen when stopping the drug.
- Failure of therapy (Failure): When the drug does not work as intended 17.
Prevalence and Impact of Adverse Drug Reactions
ADRs are a significant cause of illness and hospital admissions, with estimates suggesting they account for 0.5% to 12.8% of acute hospital admissions 2610. Studies have shown that up to 17% of hospital inpatients may experience an ADR, and fatal reactions, though rare, do occur . ADRs are especially common in patients undergoing anesthesia or intensive care .
Risk Factors and Susceptibility
Not everyone is equally at risk for ADRs. Some reactions can occur in anyone, while others only affect susceptible individuals. Factors influencing susceptibility include genetic differences, age, sex, and underlying health conditions. For example, genetic variations can lead to drug-induced hemolysis in patients with specific enzyme deficiencies 268. Pharmacogenetic factors are increasingly recognized as important in determining who is at risk .
Diagnosis and Detection of ADRs
Diagnosing ADRs often relies on clinical judgment, considering the timing of drug administration and the onset of symptoms 3410. Tools like the Naranjo score and detailed patient history are helpful, especially for drug allergies . Laboratory tests and rechallenge (re-exposing the patient to the drug) can sometimes clarify the cause .
Detection of ADRs is supported by spontaneous reporting systems, post-marketing surveillance, and case-control studies. These methods help identify new or rare reactions and improve drug safety 279.
Management and Prevention of Adverse Drug Reactions
Managing ADRs typically involves stopping the offending drug and treating the symptoms. In some cases, premedication or desensitization may be necessary, especially for drug allergies 15. Prevention strategies include careful prescribing, monitoring for known risk factors, and using genetic testing when appropriate 910.
Healthcare professionals play a crucial role in reporting suspected ADRs, which helps regulatory authorities take action to improve drug safety 1289. Pharmacovigilance—the ongoing monitoring of drug safety—is essential for minimizing the risks associated with medications 79.
Conclusion
Adverse drug reactions are a common and important challenge in healthcare, with significant impacts on patient safety and treatment outcomes. Understanding their types, risk factors, and methods for detection and management is vital for clinicians. Ongoing vigilance, reporting, and pharmacovigilance efforts are key to reducing the burden of ADRs and ensuring safer use of medicines 12345678+2 MORE.
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