Salivary phenytoin radioimmunoassay

Abstract

A simple, specific and rapid radioimmunoassay (RIA) method for the assessment of non-protein bound ('free') phenytoin (DPH) concentrations in mixed saliva is described. Epileptic patients on maintenance phenytoin therapy have mixed saliva phenytoin concentrations similar to 'free' drug levels measured directly in serum or cerebrospinal fluid (CSF), Salivary phenytoin levels are approximately 10% of the total serum level in treated epileptic patients and in normal subjects after ingestion of a single oral dose. The half time of disappearance of phenytoin after 100 or 300 mg doses is 12.2 +/- 3.0 (SD) h in serum and 12.3 +/- 3.2 (SD) h in saliva. This method of assessing the biologically active fraction of the drug may be particularly valuable in situations where serum protein binding is abnormal or in drug interactions. It is also non-invasive and requires small sample volumes (20mul) and may therefore be valuable in paediatric practice and in pharmacokinetic studies in which multiple venepunctures would otherwise be required.

Active Brownian motion of emulsion droplets: Coarsening dynamics at the interface and rotational diffusion

“…The conversion of thermal energy to mechanical work in a self-generated temperature gradient is called self-thermophoresis [33]. Janus colloids also employ other phoretic mechanisms to become active [34,35,36,37].…”

Pulling and pushing a cargo with a catalytically active carrier

“…For our system it turns out that both An and Bn vanish rapidly upon increasing n. In all cases studied, at Nmax = 100 these coefficients are smaller than 10 −20 , compared with values of the order of unity for n = 0. This behavior is sufficient for the convergence of the velocity expression in Eq (12)…”

Microswimmers in patterned environments

“…In contrast, self-propelled particles additionally take up energy from their environment and convert it into directed motion [1][2][3]; accordingly, their motion is a superposition of random fluctuations and active swimming. Examples of such microswimmers range from chemotactic cells [4][5][6] to artificial systems, where, e.g., artificial flagella are put into motion by magnetic fields [7][8][9][10] or thermophoretic forces [11]; also, micron-sized Janus particles have been realized where partial coating with a catalyst leads to non-isotropic electrochemical reactions and thus to directed motion [12][13][14]. Until now most studies have concentrated on the behaviour of microswimmers in homogeneous environments, where one typically observes a crossover from ballistic motion at short times to enhanced diffusion at long times, the latter due to random changes in the swimming direction [15][16][17].…”