Introduction

Malaria is caused by the parasite plasmodium, which is transmitted by the bite of infected mosquitoes. It is perhaps the world’s most devastating human parasitic infection. It is the most important of the parasitic diseases of humans, with transmission in 103 countries affecting 1 billion people and causing between 1 and 3 million deaths each year.[1] “Malaria is perhaps the number one public health problem in Nigeria. This oil-rich nation with wide-spread poverty accounts for 20% of the world’s malaria cases- about 110 million a year among a population of more than 130 million”.[2] Despite efforts to reduce transmission and increase treatment, there has been little change in areas which are at risk of this disease since 1992.[3] Malaria is presently endemic in a broad band around the equator, in areas of the Americas, many parts of Asia, and much of Africa; however, it is in sub-Saharan Africa where 85– 90% of malaria fatalities occur.[4] In holo- and hyperendemic areas e.g., certain regions of tropical Africa or coastal New Guinea, there is intense

P. falciparum transmission and people can sustain more than one infectious mosquito bite per day—people are infected repeatedly throughout their lives.[1] This therefore exposes them to repeated treatment with antimalarials. In a bid to curb the malaria menace, the World Health Organization strongly recommends ACT regimens as treatment for uncomplicated P. falciparum malaria cases in endemic areas.[5] These drugs are readily available to the populace in different combinations and brands. Literature consistently supports the Artemisinin Combination Therapies (ACTs) to have very few side effects. Common side effects associated with ACT administration include, vomiting, anaemia, cough and abdominal pains which incidentally are also the clinical features of malaria infection. It is therefore difficult to ascribe these findings to the ACTs. It has been suggested that high doses of artemisinin drugs can produce neurotoxicity, prolongation of the QT interval, bone marrow depression, with the possibility of long term toxicity in human beings.[6]

Studies on the effect of ACTs on hormonal parameters of the male guinea pig, report that ACTS cause significant decreases in serum testosterone levels with varying effects on LH, FSH which may be due to oxidative stress on the reproductive system of the organism.[7] Studies on guinea pigs reveal decreases in total sperm count and motility with increases in abnormal sperm cells(morphology), debris and premature sperm cells.[8]

Malaria being endemic in Africa results to repeated use of these drugs by the patients. The pharmacokinetic properties of these drugs reveal that these drugs are primarily metabolised in the liver and excreted by the kidneys. Though the half-life of the artemisinins is short approximately 3-7 days, they are combined with other drugs which have a longer half life so that the drugs stay in the circulation longer. It is for this reason that this study was carried out to evaluate the safety profile of the ACTs as it affects the liver, kidney and the heart.

Methodology

Fourteen groups (Ato N) of five mice each were used for the subacute toxicity test. Groups A,B,C,D &E received clinical doses of the Artemether CombinationTherapies;Dihydroartemisinin/piperaquine,Artesunate/amodiaquine, Artesunate/sulphadoxine/pyrimethamine, Artemether/lumefantrine and Artesunate/mefloquine. Group F received clinical doses of chloroquine while Group G received distilled water. Groups H,I,J,K & L received double clinical doses of the drugs while Group M received double clinical doses of chloroquine and Group N received distilled water. The drugs were administered orally at clinical and double clinical dose. The drugs were administered once daily for seven days and on alternate days for twenty three days. On day 30, the animals were sacrificed and the liver, kidney and heart were excised from the animals and preserved in 10% formaldehyde. These were dehydrated with ethyl alcohol and embedded in molten paraffin wax . Sections were made and stained with hematoxylin and eosin dye. The slides were then viewed under the light microscope at X400 magnification.[9]

Results

The photomicrographs of liver, kidney and heart of the Test groups animals and the control group animals are presented in Figs 1 – 6

A. The liver

Figure 1

FIG 1; LIVER OF CONTROL MICE SHOWING NORMAL CELLULAR ARCHITECTURE X 400

Figure 2

FIG 2; LIVER OF TREATED MICE THAT RECEIVED DOUBLE CLINICAL DOSE OF Artemesinin Combination Therapy SHOWING NORMAL CELLULAR ARCHITECTURE.

B. The kidney

Figure 3

FIG 3; KIDNEY OF CONTROL MICE SHOWING NORMAL CELLULAR ARCHITECTURE X 400.

Figure 4

FIG 4; KIDNEY OF TEST MICE TREATED WITH DOUBLE CLINICAL DOSE OF ACT SHOWING NORMAL CELLULAR ARCHITECTURE

C. The heart

Figure 5

FIG 5; HEART OF CONTROL MICE SHOWING NORMAL CELLULAR ARCHITECTURE. .X400

Figure 6

FIG 6; HEART OF TEST MICE TREATED WITH DOUBLE CLINICAL DOSE OF ACT SHOWING NORMAL CELLULAR ARCHITECTURE

Discussion

Histopathological examination of the test group liver, kidney and heart showed no significant changes. The test group liver showed normal hepatic cells with preserved cytoplasm, prominent nucleus and nucleolus and prominent central vein similarly the liver tissue of the control group showed normal cellular architecture as central veins were prominent and not congested. The photomicrograph of the test group kidney show no tubular necrosis, and no interstitial hemmorrhage similarly the kidney of the control group showed normal architecture with prominent tubules and undistorted glomeruli. On the heart, the test group heart revealed normal myocardium displaying branching cardiac muscle cells with centrally placed nuclei. There was no cardiac muscle congestion similarly the heart tissue from the control group animals revealed normal architecture.

The liver plays a central role in transforming and clearing chemicals and is susceptible to toxicity from these agents. Certain medicinal agents when taken in overdose and sometimes even when introduced in therapeutic ranges may injure the organ. Chemicals often cause subclinical injury to the liver. The central role played by the liver in the clearance and transformation of chemicals makes it susceptible to drug induced injury. Due to its unique metabolism and close relationship with the GIT, the liver is susceptible to injury from drugs and other substances.[10](Friedman et al;2003). The pharmacokinetics of the ACTs as reviewed also show that their primary site of metabolism is the liver, thus it would be expected that the liver would be susceptible to injury from these agents, however the results of this current study showed absence of any form of liver injury even at the microscopic or tissue level.

The kidneys can be damaged by a large number of therapeutic agents. The human kidneys together account for less than 1% of body weight yet receive about 20% of the cardiac output. They are primarily involved in filtering and concentrating various substances and chemical agents. These substances may reach high concentrations in the kidney and become toxic.[11] It is worth noting that the ACTs are primarily excreted via the kidney in the urine, thus the absence of any histological damage to the kidneys following subacute exposure to the ACTs, clearly demonstrate the safety of these agents as it affects the kidneys.

Cardiotoxicity is a major adverse effect of drugs and has led to a number of withdrawals. As many cardiotoxic effects are rare and only occur after long term use, identifying them in drug discovery stages is relatively difficult[11]. These organs were therefore evaluated in this study and results showed no pathological changes were observed after the experiment.

The results of this current research is in concordance with some other studies on ACTs on blood parameters which showed no statistically significant disturbance in blood chemistry or adverse effect on liver enzymes.[12] While literature claims that the ACTs may be neurotoxic in mice, this results are yet to be replicated in humans. Studies on AS+AQ combination reveal that it may not be neurotoxic at clinical doses.[13] Other studies on the effects of ACTs on hormonal parameters in rats showed no significant change in sperm count, motility, live/dead ratio, sperm abnormality and serum testosterone level.[14]

In conclusion, based on the findings of this study, it is safe to state that the ACTs as administered presently for the treatment of malaria are relatively safe with no observed histopathological effects on the heart, kidney and liver. We however advocate that further research work be carried out on these drugs to further confirm the safety of these agents and also to investigate the effects of the agents on the nervous system.

Acknowledgement

The authors are grateful to Dr. Seleye- Fubara and Dr. Ijomoni ( Anatomical Pathologists) for their professional assistance, Prof. O.A.Georgewill for his useful corrections and Mr Moses Itugha(Anatomist) for his technical assistance