What medications are given to an adult patient with normal renal function and a history of allergic reactions to prevent a reaction to a medication?

Premedication to Prevent Drug Allergic Reactions

For adults with normal renal function and a history of drug allergies, premedication strategies with antihistamines and/or corticosteroids have very limited proven benefit and should NOT be routinely used, with the notable exceptions of rush allergen immunotherapy and specific chemotherapy protocols where evidence supports their use. 1

Evidence Against Routine Premedication

The most recent high-quality evidence demonstrates that premedication does not provide clear benefit in most clinical scenarios:

• Very low-certainty evidence shows that glucocorticoids, antihistamines, or both do not clearly prevent biphasic anaphylaxis in patients with resolved anaphylaxis. 1 The analysis found only nonsignificant trends toward prevention with glucocorticoids (OR 0.87,95% CI 0.74-1.02) and H1 antihistamines (OR 0.71,95% CI 0.47-1.06). 1

• For patients with prior radiocontrast media (RCM) reactions receiving an alternative low- or iso-osmolar agent, premedication shows no benefit (RR 1.07,95% CI 0.67-1.71), and even under the most optimistic scenario within confidence limits, the number needed to treat would be 385. 1

• Antihistamines and corticosteroids should never be considered substitutes for epinephrine in treating actual anaphylaxis. 1

Limited Scenarios Where Premedication May Be Beneficial

Rush Allergen Immunotherapy

• Premedication demonstrates benefit with a number needed to treat of 19 (range 12-119) when the baseline anaphylaxis risk is 14%. 1

Specific Chemotherapy Protocols

• Premedication reduces anaphylaxis and infusion reactions for some chemotherapy agents (OR 0.49,95% CI 0.37-0.66), with a number needed to treat of 13 under optimal circumstances. 1
• Patients receiving platinum agents (carboplatin, cisplatin, oxaliplatin) or taxanes (paclitaxel, docetaxel) face increased hypersensitivity risk with repeat exposure and should be counseled about reaction signs, treated by staff trained in managing hypersensitivity reactions, and monitored in settings with appropriate emergency equipment. 1

Infliximab Therapy

• Premedication for infliximab shows no benefit in patients without prior anaphylaxis history (RR 1.58,95% CI 0.87-2.87). 1

Critical Pitfalls to Avoid

False Sense of Security

• Premedication side effects (sedation, confusion from first-generation antihistamines and corticosteroids) may confound recognition, assessment, and treatment of actual anaphylaxis. 1
• No premedication strategy substitutes for anaphylaxis preparedness, and breakthrough reactions occur despite premedication. 1

Medication Withdrawal Before Testing

When performing drug challenges or oral food challenges to evaluate suspected allergies, specific medications must be discontinued to avoid false-negative results:

• Cetirizine: 5-7 days before testing 1
• Loratadine: 7 days before testing 1
• Diphenhydramine and fexofenadine: 3 days before testing 1
• Hydroxyzine: 7-10 days before testing 1
• Oral H2 receptor antagonists: 12 hours before testing 1
• Oral/intramuscular/intravenous steroids: 3 days to 2 weeks before testing (based on concern for suppression of late-phase responses) 1

Drug Challenge Approach

For patients with remote, non-severe drug allergy histories:

• Direct oral drug challenge without premedication is the preferred approach for most patients with non-anaphylactic reactions to fluoroquinolones, macrolides, or trimethoprim-sulfamethoxazole occurring more than 5 years ago. 1

• One-step full-dose challenges have 95% success rates compared to 86% for two-step challenges in appropriate patient populations. 1

• Two-step challenges are reserved for: recent reactions (within 5 years), history of anaphylaxis at any time, multiple features suggesting IgE-mediated reactions (urticaria, angioedema, shortness of breath, hypotension), or significant patient anxiety. 1

The Essential Treatment: Epinephrine

Epinephrine is the only drug of choice for treating anaphylaxis, with recommended dosing of 0.3-0.5 mg intramuscularly in the anterolateral thigh for adults. 1 Delayed or absent epinephrine administration is associated with fatal outcomes in anaphylaxis. 1 There is no contraindication to epinephrine use in life-threatening anaphylaxis, even in patients with cardiovascular disease or those taking beta-blockers. 1