Abstract: The sub-Saharan African region is home to the greatest burden of Human Immunodeficiency Virus infection and Acquired Immunodeficiency Syndrome (HIV/AIDS). Appropriate management of infectious diseases is the most cost effective intervention to reduce the burden of disease. Highly Active Anti Retroviral Therapy (HAART) is the mainstay for inhibiting the multiplication of the causative agent and improving quality of life of the victims. There is some doubt in the region regarding the safety of the drugs in the anti AIDS pharmacy. Local studies on the safety of these agents are few. We studied the effects of acute and sub-acute oral administration of Lamivudine, Nevirapine and Stavudine on haematological profiles in albino rats. The rats were administered acute and sub-acute doses of Lamivudine, Nevirapine and Stavudine. Packed Cell Volume (PCV), total white blood cell count and differentials were determined by standard haematological methods. There were no significant differences (p<0.05) in the parametres except in PCV, eosinophils, neutrophils and leucocyte count associated with nevirapine and leucocytes and eosinophils associated with lamivudine. We conclude that acute and sub-acute oral administration of these drugs is associated with few haematological abnormalities and is therefore safe.
Introduction
The first report of cases of Acquired Immune Deficiency Syndrome (AIDS) appeared in the Morbidity and Mortality Weekly Report (1981) in the USA. Twenty-five years later, AIDS had become a worldwide epidemic infecting more than 65 million people of which 25 million have died (Fauci, 2006). Of the people infected with the disease, 44.2 million (68%) are in Sub-Saharan Africa, making it the region with the highest overall AIDS prevalence rate in the general adult (15-49 years) population (World Health Organization, 2005). The prevalence of HIV has been increasing steadily in Nigeria from 18% in 1991 to 3.8% in 1993, 4.5% in 1996, 5.4% in 1999 and 5.8% in 2001 (National Prevalence Survey, 2001). Appropriate management of infectious diseases is one of the most cost effective interventions to reduce the global burden of disease.
The introduction of Highly Active Antiretroviral Therapy (HAART), a cocktail of nucleoside and non-nucleoside analogues capable of inhibiting reverse transcriptase and proteases, in industrialized countries during the mid-1990s led to well documented reductions in the risk of AIDS-defining illness and AIDS related mortality (Anonymous, 2003).
The deployment of antiretroviral drugs within the concept of Highly Active Antiretroviral Therapy (HAART) for the treatment of HIV/AIDS revolutionized the management of the disease by suppressing viral loads to non-detectable levels, improving immune status and reducing the incidence of opportunistic infections, resulting in a dramatically improved clinical course and survival in infected patients (Anonymous, 2003). With AIDS becoming a global emergency, antiretroviral drugs became the most effective health care intervention (Anonymous, 2003). In most Sub-Saharan African countries there was access neither to prevention nor to treatment. But with the interventions like the Global Funds to Fight AIDS, Tuberculosis and Malaria (GFATM) in 2002, under the umbrella of the United Nations things have started to get better.
However, increasing reports of adverse clinical events and toxicities have diminished the enthusiasm generated by HAART. Some of the clinical events include AIDS- related insulin resistance, lipodystropy syndrome, gastrointestinal symptoms, hyperglycaemia, which is observed in 30-80% of patients who are well controlled with HAART (Schambelan et al., 2002; Anonymous, 2003). Haematologic abnormalities are among the most common manifestations of HIV infections and AIDS dominated by peripheral blood cytopenias (Lundgreen, 1994). The most common and troublesome toxicities of nucleoside transcriptase analogues are notably anaemia and neutropenia (Fische et al., 1990). These reports coupled with limited knowledge of HAART have generated confusion and loss of confidence amongst the population in Africa which may militate against the acceptance and compliance to these drugs (Anderson, 2005; Gebrekristos et al., 2005). Local studies on the safety of these drugs are few. This study aimed to assess the safety of the use of antiretroviral drugs (Lamivudine, Stavudine and Nevirapine) based on the effects on haematological profiles of albino rats.
Materials and Methods
Drugs and Source
The 3 antiretroviral drugs used for the study were obtained from the Pharmacy,
Usmanu Danfodiyo University Teaching Hospital, Sokoto, Nigeria. The drugs were
produced for Evans Medical Plc. Nigeria by CIPLA Limited, Verma Goa, India,
with National Agency for Food Drug Administration and Control (NAFDAC) Reg.
no. 04-6232, 04-6334 and 04-6335 for Lamivudine®,
Nevirapine® and Stavudine®,
respectively.
Chemicals
All chemicals used in the study were of analytical grade.
Animals and Treatment
Forty albino rats (Wistar Strains), three weeks old, were obtained from
Veterinary Research Institute Vom, Jos, Plateau state. The animals were housed
singly in clean cages and fed on chicken mash (Bendel Foods Ltd, Nigeria) for
3 weeks to acclimatize prior to the experiment. They were subsequently weighed
and randomly assigned into two treatment groups (16 rats per treatment group).
Members of the treatment group were further divided into four subgroups (4 per
group). Each subgroup was labelled to represent the drugs to be administered.
The drugs and dosage regimen were as follows: lamivudine® 2.0, nevirapine®
3.3 and stavudine® 0.5 mg kg-1 body weights orally, twice daily
for 2 and 4 weeks, respectively to represent acute and sub-acute dosing. The
control group was given 0.9% normal saline as placebo. The rats were weighed
daily using a weighing balance (Mettler PC, Switzerland). At the end of two
and four weeks, the animals were sacrificed painlessly under chloroform anesthesia.
Blood samples (1 mL) were collected in vacutainer tubes containing about 0.1
mL of Ethylene Diamine Tetraacetic Acid (EDTA). Haematological analyses ranging
from Packed Cell Volume (PCV), Total White Blood Cell Count (WBC) and differentials
were conducted according to standard haematological methods as reported by Dacie
and Lewis (1991).
Statistical Analysis
Statistical analysis was performed using Graph pad Instat version 3.02 (Graph
pad Corp., San Diego, USA). The data were first described using descriptive
statistics and analysis of variance (Benferroni compare all columns) was used
to test for the level of significance between means. A p value of <0.05 was
taken as statistically significant.
Results
Nevirapine
At acute administration, there was significant difference (p<0.05) in
the leucocyte and eosinophil counts when compared with controls. All other parametres
(neutrophils, monocytes and PCV) were lower compared with the controls but the
differences were not statistically significant. Upon sub acute administration
PCV and neutrophils were significantly lower (p>0.05) compared with the controls
(Table 1).
Lamivudine
Acute administration was associated with significantly (p<0.05) lower
eosinophils and leucocytes levels when compared with the controls. There was
no significant difference in the other parametres (neutrophils, monocytes, PCV)
despite being lower than the controls. Sub-acute administration was not associated
with statistically significant difference in any of the parametres (Table
2).
Stavudine
Upon acute administration monocytes counts were slightly higher compared
with the controls. Other parametres were lower but the difference was not significant
except for leucocyte count. Sub-acute administration did not result in significant
decrease in any of the parametres.
| Table 1: | Effect of acute administration of Lamivudine, Stavudine and Nevirapine on haematological indices in rats |
| Values are Means±SD, * Indicates significant difference (p<0.05), PCV = Packed Cell Volume, TLC = Total Leucocyte Count | |
| Table 2: | Effect of sub-acute administration of Lamivudine, Stavudine and Nevirapine on haematological indices in rats |
| Values are mean±SD, * Indicates significant difference (p<0.05), PCV = Packed Cell Volume, TLC = Total Leucocyte Count | |
Discussion
In this study the effect of some antiretroviral drugs on the haematological parameters of experimental rats were examined. Despite statistically significant reduction in PCV, eosinophils and leucocyte levels induced by acute and or sub-acute administration of nevirapine and lamivudine no serious effects on haematological parametres were encountered. Previous study by Janet et al. (1995) showed that toxic effect of antiretroviral drugs leads to anaemia and neutropenia. These could be as a result of these drugs interfering with the progenitor cells of the bone marrow leading to suppression of their activity. Neutropenia has been described in 16% of lamivudine and nevirapine recipients compared with 2% of those on placebo (Van Leeuwen, 1995). Nevirapine, a non-nucleoside reverse transcriptase inhibitor was more toxic than nucleoside reverse transcriptase inhibitors and was associated with several complications including anaemia in a dose dependent manner (Cinque et al., 1993). Neutropenia is also common in the advanced stages of HIV and is often caused by concomitant myelosuppression from drug therapy (Van Leeuwen, 1995).
A previous study by Ejele et al. (2004) showed that incidences of relative prevalence of anaemia, leucopenia and neutropenia declined respectively from baseline values of 84.3, 11.4 and 24.3% to post treatment values of 75.7, 11.4 and 7.1%. Consequently the prevalence of anaemia, leucopenia and neutropenia increased from baseline values of 96.0 and 6.7% after 12 weeks observational period in untreated controls. Our findings of low levels for Packed Cell Volume (PCV) and leucocytes (WBC) is at variance with high PCV and leucocytes reported by Odunukwe et al. (2001), although the drugs were administered together. The reported increase could be as a result of different mechanism of actions of these drugs acting together to improve erythropoiesis. This would be a boost to AIDS treatment as usually the drugs are administered in combination to achieve the goal of inhibiting viral replication, fusion and integration. Stavudine, Nevirapine and Lamivudine administration are not associated with so serious adverse effects as to militate against their deployment in treatment of AIDS patients. More so as the effects on haematology could be mitigated by inclusion in the treatment protocol of agents that could improve the erythropoetic process. There is therefore no scientific basis for confusion or rejection of the drugs currently in the AIDS armamentarium.