Aid for calculating dosage of oral anticoagulants has a slide with INR values set between dosage scales

摘要

A simple aid for calculating new dosage rates for oral anticoagulants comprises a slide rule type device with INR measured values on the central slider and flanked by scales for existing and new weekly dosage rates. The user merely lines up the old INR value with the old dosage rate and reads off the new dosage rate and target INR value on the other scale. The new dosage value is calculated by multiplying the old rate by the target INR value less one and divided by the existing INR value less one.