Isoniazid reaches therapeutic concentrations in serum, cerebrospinal fluid , and within caseous granulomas . It is metabolized in the liver via acetylation into acetylhydrazine. Two forms of the enzyme are responsible for acetylation, so some patients metabolize the drug more quickly than others. Hence, the half-life is bimodal , with "slow acetylators" and "fast acetylators". A graph of number of people versus time shows peaks at one and three hours. The height of the peaks depends on the ethnicities of the people being tested. The metabolites are excreted in the urine. Doses do not usually have to be adjusted in case of renal failure .
Oral intake of cissus quadrangularis (petroleum ether extract of the stem; % yield) in a rat model mimicking menopause (ovarectomized rats) at a dose of 500mg/kg for ninety days is able to fully prevent losses of bone strength and prevent up to 86% of the losses in bone thickness;  cissus quadrangularis showed comparable efficacy to /kg of the SERM known as raloxifene, and while this study is duplciated in Medline  the design has been replicated where a month of cissus quadrangularis supplementation (500mg/kg petroleum ether extract) was comparable in efficacy 25mg/kg raloxifene in ovarectomized rats.