SAHPRA warns common blood-pressure medicines can trigger life-threatening swelling

A widely used class of blood-pressure medicines can, in rare cases, cause severe swelling that blocks the airway — and the reaction can appear even after a patient has taken the medicine safely for months or years.

The South African Health Products Regulatory Authority has issued a fresh safety alert covering angiotensin-converting enzyme inhibitors, better known as ACE inhibitors. The medicines include captopril, enalapril, lisinopril, perindopril, quinapril, ramipril and trandolapril.

ACE inhibitors are routinely prescribed for conditions including high blood pressure and heart failure. They work partly by reducing the production of angiotensin II, which causes blood vessels to narrow. That allows blood vessels to relax and blood pressure to fall.

The problem SAHPRA is drawing attention to is angioedema: rapid swelling beneath the skin that can affect the face, lips, tongue, throat and other areas.

When the tongue, glottis or larynx is involved, the swelling can obstruct the airway and become life-threatening.

It can happen years after treatment starts

One of the more important points in SAHPRA's 20 August alert is that ACE-inhibitor angioedema is not restricted to people who have recently started treatment.

It can develop weeks or even years after the first dose. That means previous uneventful use does not completely rule out the medicine as a cause when unexplained facial or airway swelling develops.

The mechanism is also different from many allergic reactions.

ACE helps break down bradykinin, a substance involved in widening blood vessels. Blocking ACE can allow bradykinin levels to rise. In susceptible patients, that can contribute to angioedema.

That distinction matters in an emergency.

SAHPRA says bradykinin-mediated angioedema typically does not produce the hives or skin rash associated with some histamine-driven allergic reactions. It may also fail to respond to conventional anaphylaxis treatments such as antihistamines, adrenaline and glucocorticoids.

Healthcare professionals therefore need to consider other airway-support measures where appropriate rather than assuming a poor response to standard allergy treatment rules out angioedema.

##Once it happens, the ACE inhibitor should not come back

SAHPRA's instruction on re-exposure is particularly clear.

If a patient develops ACE-inhibitor-induced angioedema, treatment with the ACE inhibitor should be stopped and should not subsequently be restarted.

That history also needs to follow the patient.

SAHPRA warns that a prescribing or dispensing error could inadvertently expose someone to the medicine again, with potentially fatal consequences. Doctors, pharmacists and other healthcare professionals are being asked to record previous ACE-inhibitor angioedema carefully and communicate it when treatment changes hands.

An alternative blood-pressure treatment should be considered where clinically appropriate. Patients should not make that substitution themselves.

Existing South African patient information for enalapril already warns against its use in people who previously developed swelling of the face, lips, tongue or throat after treatment with an ACE inhibitor.

##What patients should watch for

People taking an ACE inhibitor should know the warning signs without assuming that the medicine is unsafe for everyone who uses it.

SAHPRA specifically highlights swelling of the lips, tongue, mouth or throat as symptoms requiring urgent medical attention, particularly because of the risk to the airway.

The regulator is not advising patients to routinely stop ACE inhibitors. These medicines remain established treatments for hypertension and heart failure. Abruptly abandoning prescribed blood-pressure or heart-failure treatment without medical guidance can create a different set of risks.

Instead, the alert is about recognising a rare but potentially severe adverse reaction quickly and preventing a patient who has already experienced it from being exposed again.

SAHPRA is also asking healthcare professionals and members of the public to report suspected cases, even where a causal relationship has not yet been confirmed. Reports can be submitted through the regulator's Med Safety App or its adverse-drug-reaction reporting channels.