Antimalarial Resistance: Is it time to turn away from ACTs?
by Olusanya Akanmu
Malaria has been a nagging challenge in Sub-Saharan Africa for centuries. 80% of the malaria cases in the world are recorded in this region. Much has been written and said about how malaria can be prevented through vector control. Also, there has been a significant decrease in the mortality rate compared to the last century. However, the disease burden is still relatively prodigious. In 2019, Nigeria accounted for approximately 23% of all malaria deaths worldwide. (WHO, 2021). Hence, the popularity of antimalarial medicines in this section of the universe.
It is therefore hardly surprising that antimalarial medicines are arguably the most popular category of medications in pharmacies. From the artemisinin derivatives to chloroquine and other antiprotozoals, clinicians seem to have a strong arsenal of medicines to tackle the illness. However, antimalarial resistance has been a recurring thing. From the 1960s to the early 1980s, there was a widespread resistance of Plasmodium falciparum to Chloroquine and the Sulphadoxine-pyrimethamine (SPs) combination which were widely used then. The failed drug therapy in this period was responsible for a severe rise in the child mortality rate. In the 1990s, Artemisinin-based combination therapies (ACTs) were introduced. Artemisinin which was derived from the sweet wormwood plant (Artemisia annua) has recorded remarkable success in malaria pharmacotherapy since then. Artemisinin derivatives are fast-acting and highly potent drugs but are fast-acting so they are usually combined with “partner” drugs. These drugs (like Lumefatrine, Piperaquine, and Amodiaquine) have a longer half-life and they help clear the remaining parasites after the standard 3-day treatment. (Nsazabana, 2019).
In 2008, resistance to ACTs was first reported along the Thailand-Cambodia border in Southeast Asia and has continued to spread across borders since then. In Nigeria, patients have presented with suspected cases of ACT resistance to community pharmacies and health centres. Researchers have divergent theories for the cause of this. Some attributed it to genetic mutations of wild-type genes in the parasite which renders them insensitive to either the artemisinin derivatives or the partner drug. Others claim the use of oral artemisinin derivatives as monotherapy as opposed to the WHO recommended combination therapy is responsible. There is also the case for the use of substandard and fake antimalarial medicines in the malaria-endemic settings. (Malaria Consortium, 2021).
In response to this development, the surveillance system has been weak by the government. Although the Dr. Tedros-led WHO team charged Nigeria and 10 other countries in 2018 on the need for proactive measures to curb the bane, there has been a little or non-existent system for data collection to monitor distribution trends to optimise response. Some clinicians have reverted to the use of chloroquine and recorded relative success. Others have resorted to Doxycycline 100mg in adult males and non-pregnant females. The use of SPs after the completion of ACTs has also been encouraged. However, ACTs remain the first-choice antimalarial medicine for many clinicians due to their percentage success and relative tolerability. This development of antimalarial resistance has placed a greater responsibility on health professionals to sensitise patients on adhering to the stipulated dosage regimen of the antimalarial prescribed. Perhaps, more than ever, there is a need for emphasis on the prevention of the disease.
References
Malaria Consortium (2021). Antimalarial drug resistance. Available at: https://www.malariaconsortium.org/pages/drug_resistance_2.htm
Nsazabana C. (2018). Resistance to Artemisinin Combination Therapies
(ACTs): Do Not Forget the Partner Drug. Tropical Medicine and
Infectious Disease 4(26).
World Health Organisation (2021). Malaria. Available at: https://www.who.int/news-room/fact-sheets/detail/malaria
