Riboflavin protective role against mitochondrial toxicity and lipodystrophy due to stavude and lamivudine

Abstract

Background Nucleoside analogues: stavudine and lamivudine represent the cornerstone of antiretroviral regimens. These drugs are associated with a range of toxicities such as peripheral neuropathy, myopathy, pancreatitis and lactic acidosis with hepatic steatosis. Fat lipodystrophy is also seen on long term antiretroviral therapy with nucleoside analogues. Given the low cost of their production compared to other antiretroviral drugs, this study was carried out to establish the role of riboflavin in protecting against mitochondrial toxicity and lipodystrophy due to their use. Methodology Swiss albino mice models were used for this study. Three dose levels of test drugs were used: half human; human equivalent and double human dose for stavudine, lamivudine and riboflavin. Four drug combinations were experimented consisting of stavudine only; stavudine and lamivudine; stavudine, lamivudine and riboflavin; and stavudine and riboflavin. The mitochondrial DNA damage was established using real time (rt) polymerase chain reaction (rt-PCR). Experimental toxicity was monitored by assessing body weight, general body appearance, glucose, lipid profile, haematology (prothrombin time-PT and activated partial thromboplastin time-APTT) and histology. Liver and adipose tissue were extracted and blood collected. Data were analysed using SPSS version 17.0. Results The reference ranges for the parameters: live weight, liver, blood glucose, lipid and haematological profile for healthy untreated mice were established. These wre subsequently applied in the interpretation of experimental data.There was statistical significant rise in blood glucose levels in groups treated with stavudine and lamivudine at all dose levels (p= 0.001- 0.011). Although there was an increase in blood glucose levels in groups treated with combination of stavudine and lamivudine plus riboflavin, the increase was not statistically significant except for the groups treated with double human equivalent dose (p= 0.001-0.007). However, groups treated with double human equivalent dose of stavudine and riboflavin showed decrease in blood glucose (p= 0.003). There was no dyslipidaemia noted in the groups treated with human and double human equivalent dose. However, the total cholesterol and triglycerides levels were below the reference range for groups treated with combination containing riboflavin for half human equivalent group. The statistical significance for the total cholesterol and triglycerides in the group treated with combination of half human equivalent dose stavudine and riboflavin were statistically significant at 0.034 and 0.02 respectively. Adipose tissue was depleted in the groups treated with stavudine human equivalent and double human equivalent doses. There was significant increase in PT for groups treated with human equivalent dose of stavudine and stavudine plus lamivudine (p= 0.024-0.03). However, addition of riboflavin to double human equivalent dose of stavudine was associated with a significant decrease in PT (p= 0.000). Similarly, the APTT significantly increased for group treated with human equivalent dose of stavudine and combination of stavudine and lamivudine (p= 0.008-0.016) but significantly decreased on addition of riboflavin to double dose of stavudine (p= 0.000). This is a beneficial effect. Generally, there was liver derangement leading to hepatitis, steatosis and granuloma however, these were found to be less severe in groups treated with riboflavin. Mitochondrial DNA was measured by decrease in ct values compared with untreated group. For the group treated with half human equivalent dose of stavudine, the ct values for the liver (p=0.02) and adipose tissue (0.02) were increasing. The same trend for increasing ct values (liver p=0.03; and adipose tissue p=0.012) was reported in the group treated with half human equivalent dose combination of stavudine and lamivudine. The ct values decreased on addition of riboflavin. The ct values for the liver in group treated with human equivalent dose combination of stavudine and lamivudine was reported to increase compared to untreated group (p=0.003). The ct values for the liver reduced in the groups treated with human equivalent dose combinations of: stavudine, lamivudine and riboflavin (p=0.021); and stavudine and riboflavin (p=0.002). The group treated with double human equivalent dose combination of stavudine and lamivudine, liver and adipose tissue ct values were increased with statistical correlation of 0.001 and 0.007 respectively. Conclusion The reference ranges for biochemical and haematological parameters were established. Toxicity due to the drugs stavudine and lamivudine was confirmed for human and double human equivalent doses. Riboflavin was found to have protective effect to mtDNA when in combination with stavudine; and stavudine and lamivudine in animal model. Half human equivalent dose was found to cause minimal toxicity