From the Guidelines
The patient should discontinue both chlorthalidone and diltiazem immediately and seek medical attention, as the hives indicate an allergic reaction to one or both medications. The healthcare provider should document this reaction in the patient's chart and consider alternative medications for managing hypertension and tachycardia.
Alternative Medications
For hypertension, alternatives to chlorthalidone might include:
- ACE inhibitors like lisinopril (starting at 10mg daily) or
- ARBs such as losartan (starting at 50mg daily) 1. For tachycardia, alternative rate-controlling agents like metoprolol (starting at 25mg twice daily) or atenolol (starting at 25mg daily) could be considered.
Allergic Reaction
The allergic reaction is likely due to either a direct immune response to the medication structure or to metabolites formed during drug processing in the body.
Future Medication Choices
It's essential to monitor the patient after starting any new medication regimen and to consider allergy testing if appropriate to determine which specific drug caused the reaction, as this will help guide future medication choices and prevent similar reactions.
Guidelines
According to the 2024 ESC guidelines for the management of elevated blood pressure and hypertension, ACE inhibitors, ARBs, dihydropyridine CCBs, and diuretics (thiazides and thiazide-like drugs such as chlorthalidone and indapamide) have demonstrated the most effective reduction of BP and CVD events, and are therefore recommended as first-line treatments to lower BP 1.
Diltiazem
Diltiazem, a non-dihydropyridine CCB, should be avoided in patients with ischemic systolic HF with hypertension due to its negative inotropic properties and the increased likelihood of worsening HF symptoms 1.
From the FDA Drug Label
Patients should inform their physician if they have: (1) had an allergic reaction to chlorthalidone or other diuretics or have asthma The following postmarketing events have been reported infrequently in patients receiving diltiazem hydrochloride tablets: acute generalized exanthematous pustulosis, allergic reactions, angioedema (including facial or periorbital edema), erythema multiforme (including Stevens-Johnson syndrome, toxic epidermal necrolysis), The patient is experiencing hives, which is a symptom of an allergic reaction.
- The patient should inform their physician about the allergic reaction.
- The physician should consider discontinuing either chlorthalidone or diltiazem to prevent further allergic reactions 2 3.
From the Research
Patient's Condition
The patient is a 63-year-old with tachycardia and hypertension, started on chlorthalidone and diltiazem, and has begun to experience hives.
Medication Side Effects
- Chlorthalidone is a thiazide-like diuretic, and its side effects can include allergic reactions, such as hives 4.
- Diltiazem is a calcium channel blocker, and its side effects can also include allergic reactions, although this is less common 5.
Treatment Options
- The ALLHAT study found that chlorthalidone was effective in reducing hypertension-related morbidity and mortality, and it is considered a good option for first-step antihypertensive therapy 6.
- The study by 5 found that chlorthalidone and diltiazem both reduced myocardial ischemia in elderly patients with hypertension and coronary artery disease.
- However, given the patient's allergic reaction to the current medication, alternative treatment options may need to be considered.
Alternative Treatments
- Other diuretics, such as hydrochlorothiazide, may be considered as an alternative to chlorthalidone 4, 7.
- Other calcium channel blockers, such as amlodipine, may be considered as an alternative to diltiazem 6.
- The patient's treatment plan should be reassessed, and alternative medications should be considered to manage their hypertension and tachycardia while minimizing the risk of allergic reactions.
Discontinuation of Medication
- If the patient's medication needs to be discontinued due to an allergic reaction, it is essential to monitor their blood pressure and cardiovascular health closely 8.
- The study by 8 found that temporary discontinuation of antihypertensive medication was well-tolerated in patients with difficult-to-control hypertension, but it is crucial to weigh the risks and benefits of discontinuing medication on a case-by-case basis.