Syncope following oral chloroquine administration in a hypertensive patient controlled on amlodipine

Suspected Hydroxychloroquine-Induced Sinus Bradycardia and QTc Prolongation in a Patient with COVID-19

An 84-year-old woman with hypertension, Alzheimer's disease, and chronic kidney disease presented with fever and was diagnosed with corona virus disease 2019 (COVID-19). During the hospitalization, she experienced unexpected sinus bradycardia with prolonged QTc, which was thought to be closely related to the short-term use of hydroxychloroquine (HCQ), an old drug used to treat malaria and autoimmune diseases, but now used against COVID-19. The cardiac side effects of HCQ were rare, seen with short-term and low-dose use. With the COVID-19 pandemic, this case alerts clinicians to be aware of the arrhythmogenic effects of HCQ when it is used as an antiviral drug, especially in patients with preexisting cardiovascular diseases.

Acute chloroquine and hydroxychloroquine toxicity: A review for emergency clinicians

Background

Acute chloroquine and hydroxychloroquine toxicity is characterized by a combination of direct cardiovascular effects and electrolyte derangements with resultant dysrhythmias and is associated with significant morbidity and mortality.

Objective

This review describes acute chloroquine and hydroxychloroquine toxicity, outlines the complex pathophysiologic derangements, and addresses the emergency department (ED) management of this patient population.

Discussion

Chloroquine and hydroxychloroquine are aminoquinoline derivatives widely used in the treatment of rheumatologic diseases including systemic lupus erythematosus and rheumatoid arthritis as well as for malaria prophylaxis. In early 2020, anecdotal reports and preliminary data suggested utility of hydroxychloroquine in attenuating viral loads and symptoms in patients with SARS-CoV-2 infection. Aminoquinoline drugs pose unique and significant toxicological risks, both during their intended use as well as in unsupervised settings by laypersons. The therapeutic range for chloroquine is narrow. Acute severe toxicity is associated with 10–30% mortality owing to a combination of direct cardiovascular effects and electrolyte derangements with resultant dysrhythmias. Treatment in the ED is focused on decontamination, stabilization of cardiac dysrhythmias, hemodynamic support, electrolyte correction, and seizure prevention.

Conclusions

An understanding of the pathophysiology of acute chloroquine and hydroxychloroquine toxicity and available emergency treatments can assist emergency clinicians in reducing the immediate morbidity and mortality associated with this disease.

Are Antimalarial Hybrid Molecules a Close Reality or a Distant Dream?

Emergence of drug-resistant Plasmodium falciparum strains has led to a situation of haste in the scientific and pharmaceutical communities. Hence, all their efforts are redirected toward finding alternative chemotherapeutic agents that are capable of combating multidrug-resistant parasite strains. In light of this situation, scientists have come up with the concept of hybridization of two or more active pharmacophores into a single chemical entity, resulting in "antimalarial hybrids." The approach has been applied widely for generation of lead compounds against deadly diseases such as cancer and AIDS, with a proven potential for use as novel drugs, but is comparatively new in the sphere of antimalarial drug discovery. A sudden surge has been evidenced in the number of studies on the design and synthesis of hybrids for treating malaria and may be regarded as proof of their potential advantages over artemisinin-based combination therapy (ACT). However, it is evident from recent studies that most of the potential advantages of antimalarial hybrids, such as lower toxicity, better pharmacokinetics, and easier formulation, have yet to be realized. A number of questions left unaddressed at present need to be answered before this approach can progress to the late stages of clinical development and prove their worth in the clinic. To the best of our knowledge, this compilation is the first attempt to shed light on the shortcomings that are surfacing as more and more studies on molecular hybridization of the active pharmacophores of known antimalarials are being published.