Due to a small sample size supporting this revised equation, free phenytoin levels are strongly recommended whenever possible. Because phenytoin is highly protein bound and only unbound drug is capable of crossing the blood-brain barrier to exert its pharmacologic effect, unbound free phenytoin levels may be more clinically relevant than total levels to maximize efficacy and minimize toxicity. Topics are richly illustrated with more than 40, clinical photos, videos, diagrams, and radiographic images.
The follow-up visits showed similar results. Equation parameters such as Renal Fx have two or more discrete values that may be used in the calculation.
The original Winter-Tozer equation 6 displayed below was developed in patients with epilepsy assuming a normal serum albumin of 4.
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Because of limitations in the data, it is not clear whether a coefficient of 0. More than monographs are provided for prescription and over-the-counter drugs, as well as for corresponding brand-name drugs, herbals, and supplements. Easily compare tier status for drugs in the same class when considering an alternative drug for your patient. This study was designed to investigate whether serum albumin-adjusted phenytoin levels in Indian patients with epilepsy predict clinical outcome better than total phenytoin levels.
We can't guarantee that ClinCalc. Accuracy of two equations in determining normalized phenytoin concentrations. Fifty patients with epilepsy were included in the study and were followed-up for a period of 6 months.
Due to its narrow therapeutic index and non-linear pharmacokinetic profile, phenytoin therapeutic drug monitoring is recommended. On the basis of available literature, the following coefficients are provided by this clinical calculator:.
At Visit 1, mean serum albumin levels were Revised Winter-Tozer equation studied in neurointensive care unit patients; significantly more accurate than the traditional equation. In developing countries like India, where estimation of free drug levels is expensive and suitable equipment is not available in most centers, serum albumin-adjusted levels can be used by pharmacologists to predict response and thus assist in clinical decision-making.
Customize your Medscape account with the health plans you accept, so that the information you need is saved and ready every time you look up a drug on our site or in the Medscape app. More than anatomy articles feature clinical images and diagrams of the human body's major systems and organs. Home Academy Blog About. Drug images are also included.