Olfactory and gustatory disturbances caused by digitalism: A case report

QT shortening: a proarrhythmic safety surrogate measure or an inappropriate indicator of it?

OBJECTIVE

To examine whether QT interval shortening is an overlooked adverse event as compared to QT prolongation through a review of preclinical, clinical and post-marketing adverse event data available to the regulator for centrally and nationally authorized medicinal products.

METHODS

Potential safety signals of QT shortening related to authorized medicinal products were detected from Eudravigilance using proportional reporting ratios. Active substances identified as having unexpected signals of QT shortening were assessed in depth using the Bradford-Hill criteria for causation. Preclinical, clinical and adverse event data related to each active substance was used in the assessments. Post marketing adverse event cases were reviewed for imputability using the French method.

RESULTS

80 adverse event cases of electrocardiogram QT shortening were detected from 13 different active substances which included antipsychotics and antiepileptics (Clozapine, Ziprasidone, Quetiapine, Olanzapine, Carbamazepine), cardiovascular drugs (Atenolol, Digoxin, Ramipril, Simvastatin), anti-inflammatories and analgesics (Ibuprofen, Paracetamol) and other substances Calcium Carbonate (Mineral Supplement/Antacid) and Fingolimod (Immunosuppressant). By comparison 404 active substances were found have a potential safety signal of Electrocardiogram QT prolongation. Following in depth review none of the 13 active substances identified were found to be clearly associated with QT shortening using the minimum level of evidence for regulatory action. In the preclinical data reviewed we observed cases of morphological changes to the action potential (AP) where the Action Potential Duration at 90% (APD₉₀) was not affected.

CONCLUSIONS

From a regulatory perspective one cannot refute the possibility of a clinically relevant risk from QT shortening through the current testing requirements. Lack of further investigations into any potential morphological changes to the AP, or APD₉₀ shortening beyond a specified threshold in our opinion does not fully exclude the possibility of proarrhythmic effects of active substances.

Antiarrhythmic drug-induced smell and taste disturbances: A case report and literature review

RATIONALE

Metoprolol and amiodarone are common antiarrhythmic drugs used in clinics throughout the world. The taste and smell alterations induced by antiarrhythmic drugs remain uncommon throughout the world, with less than 10 reported cases.

PATIENT CONCERNS

In this case report, we describe a case of a 73-year-old female, diagnosed with arrhythmias, was treated for metoprolol. At the third week of metoprolol treatment, the patient noticed a qualitative change in her ability to smell, also called dysosmia. After the metoprolol was tapered, her ability to smell was recovered. However, her arrhythmia was getting worse and the patient was given amiodarone. After using amiodarone for about 2 weeks, the patient felt hypogeusia, or loss of taste sensation.

DIAGNOSES

The patient was diagnosed as dysosmia and taste disturbance induced by the antiarrhythmic drugs.

INTERVENTIONS

After noticed the side effects of the antiarrhythmic drugs, we asked the patient to abandon the drugs and have a radiofrequency ablation.

OUTCOMES

Her ability of smell and taste were recovered after withdrawing the antiarrhythmic drugs. Also, in the follow-up appointment, she reported no complaints of smell or taste anymore.

LESSONS

These rare sensory disorders induced by anti-arrhythmic drugs were less documented in past literature. Our case report describes a patient with an arrhythmia who suffered reversible dysosmia and hypogeusia after taking metoprolol and amiodarone, respectively. We conclude that smell and taste disorders should be made aware to patients during the anti-arrhythmic treatment, helping to promote the safety of patients and drug compliance.

Effects of aging on the human taste system

Losses in taste perception as well as distortions of gustatory function occur with greater frequency in older individuals, and these changes are exacerbated by certain medical conditions, pharmacologic interventions, radiation, and exposure to toxic chemicals. Medications, especially drug-drug interactions, are the most significant yet underappreciated contributors to taste disorders in the elderly. Taste disorders frequently occur when the fraction of an orally administered drug dose that reaches the systemic circulation is markedly increased due to inhibition (by a coadministered drug) of the efflux transporter P-glycoprotein and/or inhibition of the cytochrome P450 metabolism system, which normally limit systemic availability of drugs. The supratherapeutic plasma drug concentrations that result from drug-drug interactions can induce a taste from the blood side of taste cells (intravascular taste), alter taste cell biochemistry, and/or modify other aspects of the taste pathways.