The lowest dose achieved in these patients did not correlate with patient weight, frequency of administration, disease duration or pretherapeutic level of disability, and the amplitude of dose reduction was independent of disease duration. An important question for neurologists to ask is how to balance the dose reduction with the risk of the patient’s condition

relapsing. Kuitwaard et al. evaluated IVIg pharmacokinetics selleck chemicals in 174 GBS patients receiving 0·4 g/kg/day for 5 days, and noted that the peak serum IgG concentration occurred 2 weeks after treatment, although with a high variability between patients [13]. When the patients were separated into quartiles according to the increase in serum IgG concentration [cut-off values of ΔIgG MG-132 supplier for quartile 1: <3·99 g/l (n = 43); quartile 2: 3·99–7·30 g/l (n = 45); quartile 3: 7·31–10·92 g/l (n = 43); and quartile 4: >0·92 g/l (n = 43)], those in the lowest quartile had a more severe clinical outcome (P < 0·001) in a number of measures, including clinical deficits, poor outcome, higher frequency of mechanical ventilation and time to reach a GBS disability score of 2, indicating that these patients would benefit from a higher dose of IVIg. A more recent pharmacokinetic study described 25 CIDP patients with active but stable

disease in whom the dose of IVIg had been optimized individually Interleukin-2 receptor [14]. Serum IgG levels were measured 5 min after infusion and compared with baseline measurements. The change in IgG levels was associated with IVIg dosage, but not treatment frequency, and both inter- and intrapatient variability was low,

leading the authors to conclude that constant serum IgG levels are required to stabilize CIDP patients. Similarly, when evaluating serum IgG levels in MMN patients receiving a cumulative dose of 2·0 g/kg for 5 days, wide variation was observed in total IgG and change in IgG levels between patients [15]. When comparing responders (defined as an increase in muscle strength of at least one Medical Research Council point in minimally two muscle groups) with non-responders, the authors noted that at each time-point (1 day, 5 days or 3 weeks after treatment) the change in IgG levels was higher in the IVIg responders than in the non-responders. The pharmacokinetic studies indicate that it is important to maintain serum IgG levels in order to achieve disease stability in patients with neurological disorders, and increasing dose frequency may assist with this goal. For example, a reduction in the IVIg treatment interval from 3-weekly to weekly administration may enable lower dosing while achieving higher serum IgG trough levels [16].