Norditropin SimpleXx: a liquid human growth hormone formulation, a pen system and an auto-insertion device. 
Patient compliance is of vital importance for the outcome of any medical therapy.  Compliance is especially a problem in long-term treatment of non-life threatening diseases, such as growth retardation in children.  Until recently, all human growth hormone (hGH) products required a reconstitution process.  Norditropin((R)) SimpleXx(TM) is a liquid formulation of the biosynthetic hGH product Norditropin((R)), and, together with an improved NovoPen((R)) 1.5, NordiPen(TM), and an auto-insertion device, PenMate(TM)/NordiPenMate(TM), it has been developed in order to ease the injection process for patients.  A randomized, open, multicentre, crossover trial compared Norditropin((R)) SimpleXx(TM)/improved NovoPen((R)) 1.5 with freeze-dried Norditropin((R)) PenSet((R))/Nordiject((R)).  A total of 67 children with GH deficiency, aged 5-18 years, were treated with either Norditropin((R)) SimpleXx(TM) for 6 weeks followed by Norditropin((R)) for 6 weeks or the opposite (sequences I and II, respectively).  Acceptability/convenience and pain perception were evaluated by questionnaire after each period.  The function and handling of the PenMate(TM) were evaluated in a Dutch trial by 27 GH-treated children with intrauterine growth retardation, aged 4-16 years, and their parents.  All children were accustomed to using the Nordiject((R)) pen.  The evaluation of the PenMate(TM) was based on a questionnaire.  A similar trial was conducted in England, in which the NordiPen(TM) and the NordiPenMate(TM) were evaluated by 25 GH-treated children and their parents.  Norditropin((R)) SimpleXx(TM) was found to be easier to inject by 64% of the children, and 98% of the children found the system easier to use overall.  There was no difference in pain perception between the two administration systems, as judged by questionnaires and visual analogue scale score.  Three out of four patients preferred to continue treatment with Norditropin((R)) SimpleXx(TM).  The safety profiles of the two systems were similar.  In the Dutch trial, the PenMate(TM) was found to be easy and safe to handle, even for very young children (aged 4-5 years).  Of patients who took a long time to get used to the injections, 73% found that the new pen would help.  A total of 88% of the children would prefer to use the PenMate(TM) in the future.  Positive results of the handling tests were also reported in the British trial.  The use of Norditropin((R)) SimpleXx(TM) and the auto-insertion device may improve patient compliance.