A method to prevent the loss of isoniazid and acetylisoniazid in human plasma.

Abstract

Plasma concentrations of isoniazid and N-acetylisoniazid were measured at varying times after addition of both compounds to plasma (5 ,ug/ml) and storage at several different temperatures (-70°C, -20°C, 4°C and 20°C). The concentration of both compounds declined log-linearly with time and the half-life of decline was shorter with increasing temperature of storage. Both compounds were stable for at least 5 weeks, however, when stored at -70°C. We conclude that this temperature should be used to prevent loss of both compounds during storage and transport of samples.

A Sensitive HPLC Method for Determination of Isoniazid in Rat Plasma, Brain, Liver and Kidney

“…The method can be used for the routine analysis of INH in plasma, brain, liver and kidney (small retention time). No degradation of INH in plasma was observed as reported earlier [19].…”

“…Poor retention of polar compounds has been reported earlier on non polar reverse phase HPLC columns earlier [15], however, numerous methods for determination of polar compounds using reverse phase columns specific to isoniazid exists in the literature [16][17][18][19]. Establishment of a reproducible analytical method is always prerogative step before the development of a pharmaceutical product.…”

Saliva and plasma concentrations of isoniazid and acetylisoniazid in man.

“…Blood samples were collected at 15, 30, 45, 60, 90, 120, 180, 240, 300 and 360 min. Saliva samples (stimulated by chewing teflon tape) were collected at the same times. Plasma was immediately separated by centrifugation and stored along with the saliva samples at -70°C to prevent the breakdown of isoniazid and acetylisoniazid (Hutchings et al, 1983a(Hutchings et al, , 1988 and equilibrium dialysis at 370 C against Sorensen's phosphate buffer (pH 7.4) using a Dianorm apparatus (Diachema, A.F. Zurich) and regenerated cellulose dialysis membrane (Spectrapor II) of molecular weight cut-off 12000-14000.…”

The effect of thyrotoxicosis on isoniazid acetylation.

“…Because of instability of isoniazid in blood, (Hutchings et al, 1983b) (John & Jones, 1984). Isoniazid and acetyl isoniazid were assayed by high performance liquid chromatography (Hutchings et al, 1983b).…”

“…Isoniazid and acetyl isoniazid were assayed by high performance liquid chromatography (Hutchings et al, 1983b). Samples stored at -70°C have been shown to retain full isoniazid activity for 5 weeks and all were analysed within this period (Hutchings et al, 1983b treatment, all patients were clinically euthyroid and all but one had thyroid hormone levels within the normal range. This patient had received radioiodine therapy and became biochemically hypothyroid between his outpatient visit and being able to return for repeat study.…”