Section 4: ADR and Toxicity Surveillance

You cannot monitor every patient for every possible adverse effect of every drug. This would be an impossible and inefficient task. The art of effective surveillance is triage. You must use your clinical judgment and the tools at your disposal to focus your efforts on the patients and medications that pose the highest risk. This involves a two-pronged approach: a drug-focused strategy and a patient-focused strategy.

4.2.1 Drug-Focused Surveillance: The “Usual Suspects”

Certain medications have a well-known, predictable toxicity profile and a narrow therapeutic index. Any patient on one of these “usual suspects” should automatically be on your daily surveillance list. Your pre-rounding workup should specifically flag these patients, and your bedside review should include a targeted search for the classic signs of toxicity associated with that drug.

4.2.2 Patient-Focused Surveillance: The Vulnerable Hosts

Independent of the specific drugs they are on, certain patients are inherently more susceptible to developing ADRs due to their physiological state. These patients warrant a closer look, even if their medication list seems benign.

• Patients with Organ Dysfunction:
  • Renal Impairment (CKD or AKI): These patients are at extremely high risk for accumulation and toxicity of renally cleared drugs. Your primary role is dose adjustment and monitoring for signs of toxicity.
  • Hepatic Impairment (Cirrhosis): These patients have reduced drug metabolism and are highly susceptible to oversedation from opioids and benzodiazepines.
• Elderly Patients (≥65 years): Due to age-related declines in renal function, reduced hepatic metabolism, and increased sensitivity to many drugs (especially those with anticholinergic or CNS effects), elderly patients are at very high risk. Always screen their profiles for inappropriate medications using the Beers Criteria.
• Patients with Polypharmacy (>10 medications): The risk of a significant drug-drug interaction or an additive adverse effect increases exponentially with the number of medications a patient is taking.
• Patients with a History of Allergy/ADRs: A patient who has had a significant ADR in the past is more likely to have one again. Pay close attention to their listed allergies and avoid any related medications.

This is the practical core of your surveillance workflow. We will now walk through a systems-based “review of systems,” but from a pharmacist’s perspective. For each major organ system, we will identify the key signs of drug-induced toxicity to look for in both the EHR and at the bedside.

Identifying an adverse drug reaction is only the first step. Your professional responsibility extends to documenting the event, reporting it through the proper channels, and taking steps to prevent its recurrence. This “closing of the loop” is what differentiates a simple observation from a meaningful clinical intervention that improves safety for both the current patient and for future patients.

4.4.1 Step 1: Document Your Findings in the EHR

Your first action after identifying an ADR and communicating it to the team is to write a formal pharmacy progress note. This creates a permanent record of your assessment and actions. Your note should be clear, concise, and defensible, following the SOAP format.

Adverse Drug Reaction Assessment

S: Patient reports new-onset, diffuse, non-pruritic maculopapular rash to chest and back.

O: Patient is a 72yo male on day #5 of piperacillin-tazobactam for HAP. Vitals stable, afebrile. WBC is 8.5. No other new medications started.

A: The new rash is likely a delayed, non-IgE-mediated hypersensitivity reaction to piperacillin-tazobactam. The reaction appears morbilliform and there are no signs of severe cutaneous adverse reaction (e.g., no mucosal involvement, no blisters, no fever).

P:
1. Discussed findings with Dr. Jones. Recommended discontinuing piperacillin-tazobactam and switching to meropenem to complete therapy. Verbal order received.
2. Recommend symptomatic management with oral diphenhydramine PRN.
3. Will update patient's allergy profile to reflect a "rash" reaction to piperacillin-tazobactam.
4. Will submit a formal medication event report.

4.4.2 Step 2: Update the Allergy Profile

This is a simple but critically important step. The allergy list in the EHR is the most visible and powerful tool for preventing future harm. It is your responsibility to ensure it is accurate. When you identify a true ADR, you must update the profile with:

• The correct drug/class.
• A clear description of the reaction. “Hives” is much more useful than “Allergy.” “Anaphylaxis” is a critical distinction. “Nausea” is likely an intolerance, not a true allergy, and should be documented as such.

4.4.3 Step 3: File a Formal Event Report

In addition to your clinical note, you must file a formal medication event or safety report through your hospital’s online reporting system. This is not a punitive action; it is a vital data collection tool. These reports are aggregated and analyzed by the medication safety officer (often a pharmacist) and the P&T committee to identify trends and system-level vulnerabilities. Your single report might be the one that highlights a recurring problem with a specific drug or process, leading to a hospital-wide policy change that protects countless future patients.

Furthermore, for serious, unexpected, or novel adverse reactions, it is your professional responsibility to consider reporting the event externally to the FDA’s MedWatch program. This is how post-marketing surveillance works and is a critical contribution to the global understanding of drug safety.