Chronic kidney disease (CKD) has a high prevalence, affects between 3% and 17% of the general population, and tends to increase with age. Currently, 0.1% of the population is in end-stage renal failure and requires dialysis replacement therapy [1,2,3,4,5,6]. Renal failure and extrarenal purification techniques change the pharmacokinetics of the majority of drugs [7,8,9]. The dosage of nearly 50% of pharmacological treatments must be adjusted by considering renal failure severity and the replacement therapy used. These adjustments concern a very large number of patients; therefore any prescribing physician will sooner or later have to deal with this issue.
After identifying a patient with renal failure, the main challenge for the clinician is to determine which drug should be adapted and to what extent. In most drug directories, the available information regarding this topic is evasive or absent, and divergent information can be found, even in specialized directories . As a result, most practitioners neglect this aspect, especially when they have not been educated about kidney issues.
In a clinical study carried out in a 720-bed general hospital in Boston, Chertow et al.  showed that 43% of the prescriptions given to 7,904 patients with renal failure were non-compliant. Failure to adapt to CKD increases adverse events, sometimes with serious toxic consequences, including torsades de pointes-type malignant arrhythmias, bone marrow aplasia, acute renal failure, fulminant hepatitis, epilepsy, coma, etc.
Hug et al.  performed a retrospective study in six US public hospitals and found that out of 17,614 patients with CKD, more than 50% experienced a probable adverse reaction and 10% displayed a proven adverse reaction to one or more drugs. In more than 90% of these cases, ineffective dose adjustment to renal failure was involved. Of all the adverse events identified, 50% were considered as serious, with 4.5% being life-threatening. The failure to adjust drug doses to renal failure is therefore far from being an isolated problem. It is responsible for dangerous and costly iatrogenic diseases, which represent a real public health problem .
Conversely, excessive or "blind" dose reduction can result in particularly harmful therapeutic inefficiency, especially in intensive care units, but also in onco-hematology and infectiology. The fear of therapeutic error can also lead clinicians to stop proposing certain treatments, particularly in the field of cardiovascular prevention . It is therefore essential to prescribe the right dose to obtain the optimal therapeutic quality. To achieve this goal in daily clinical practice, the correct information must easily and quickly be available, with automatic reminders whenever possible.
Even though all pharmacokinetic parameters may be altered, CKD primarily results in altered urinary excretion of unchanged active ingredient or its metabolites. This leads to an accumulation phenomenon with half-life (t1/2) prolongation, the extent of which varies according to renal failure stage and lowered glomerular filtration rate (GFR) [7,8,9].
Therefore, drug adjustment primarily consists of reducing maintenance doses or extending the interval between doses, depending on the stage of renal failure (1 to 5). There is a specific maintenance dose for each GFR level. However, the route of administration (intravenous, oral, intramuscular, etc.) and loading dose, which depend on bioavailability and distribution volume, respectively, are usually unchanged [8,9].
Extrarenal drug replacement therapy introduction in turn modifies the pharmacokinetics of many active ingredients, increasing their elimination [8,9], which requires a new dosage adjustment. In rare cases, doses must paradoxically be adjusted upwards, particularly when treating a patient with "uremic resistance" related to number or sensitivity reduction of peripheral drug receptors. Diuretics, and especially loop diuretics, are a typical example [15,16]. Finally, the nephrotoxicity of certain molecules must particularly be considered in uremic patients [17,18]. This aspect weighs heavily in the benefit/risk balance inherent in any treatment, frequently leading to contraindication in the case of CKD.
All these clinical, pharmacological, and toxicological considerations are integrated in RenAdaptor©. This computerized drug repertory compiles the international recommendations regarding the dosage adaptation to the different renal failure stages and extrarenal purification techniques. A team of nephrologists, clinical pharmacists, and computer scientists have been working for more than 20 years on the development of this software, motivated by the difficulties encountered by clinicians in finding this type of information in their daily practice.
All the data provided by the software are primarily taken from the labels issued by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA), but also from the most recent international medical and pharmaceutical literature. The molecules are classified into four levels according to a clinically relevant pharmacotherapeutic classification and to the international "Anatomical Therapeutic Chemical" (ATC) classification system. More than 1,900 drugs, with their international nonproprietary name (INN) and brand name available for 30 countries, and around 20,000 specific references are mentioned in the database. The database is continually updated, and all drugs approved by the EMA and the FDA since 2009 are available. Molecules which are not yet available will gradually be included in order to cover the entire world's pharmacopoeia in the next years.
Renadaptor© is practical, up-to-date, and its integration into hospital prescription software (Computerized Physician Order Entry [CPOE] systems) is fairly easy as it is written in php-mysql language. Thanks to automatic reminders, the integration of Renadaptor into CPOE systems has already shown a quality improvement of the proposed treatments [10,19]. The general recommendations regarding prescriptions for renal failure patients are the subject of an international consensus published in the KDIGO (Kidney Disease Improving Global Outcomes) .
Finally, it should be remembered that, despite adequate dosage adjustment, patients with renal failure are at greater risk of developing adverse or toxic effects, due to their specific fragility and individual pharmacokinetic changes [18,21,22,23]. The clinician must therefore remain vigilant when treating this type of patient, and each of his/her prescriptions, for which he/she is responsible, must be carefully considered.
 Hill NR, Fatoba ST, Oke JL, Hirst JA, O Callaghan CA, Lasserson DS, Hobbs FD. Global Prevalence of Chronic Kidney Disease - A Systematic Review and Meta-Analysis. PLoS One. 2016 Jul 6;11(7):e0158765.
 Frimat L, Loos-Ayav C, Briançon S, Kessler M. Epidémiologie des maladies rénales chroniques. EMC néphrologie . Paris : Elsevier Masson ; 2005. 18-025-A/B-10.
 Clase CM, Grag AX, Kiberd BA. Prevalence of low glomerular filtration rate in nondiabetic Americans : Third National Health and Nutrition Examination Survey (NHANES III). J Am Soc Nephrol 2002 ; 13(5) : 1338-49.
 Brück K, Stel VS, Gambaro G, Hallan S, Völzke H, Ärnlöv J, Kastarinen M, Guessous I, Vinhas J, Stengel B, Brenner H, Chudek J, Romundstad S, Tomson C, Gonzalez AO, Bello AK, Ferrieres J, Palmieri L, Browne G, Capuano V, Van Biesen W, Zoccali C, Gansevoort R, Navis G, Rothenbacher D, Ferraro PM, Nitsch D, Wanner C, Jager KJ; European CKD Burden Consortium. CKD Prevalence Varies across the European General Population. J Am Soc Nephrol. 2016 Jul;27(7):2135-47.
 Hill NR, Fatoba ST, Oke JL, Hirst JA, O'Callaghan CA, Lasserson DS, Hobbs FD. Global Prevalence of Chronic Kidney Disease - A Systematic Review and Meta-Analysis. PLoS One. 2016 Jul 6;11(7):e0158765.
 Hsu RK, Powe NR. Recent trends in the prevalence of chronic kidney disease: not the same old song. Curr Opin Nephrol Hypertens. 2017 May;26(3):187-196.
 Lea-Henry TN, Carland JE, Stocker SL, Sevastos J, Roberts DM. Clinical Pharmacokinetics in Kidney Disease: Fundamental Principles. Clin J Am Soc Nephrol. 2018 Jul 6;13(7):1085-1095.
 Aronoff GR, Bennett WM, Berns JS, Brier ME, Kasbekar N, Mueller BA, Pasko DA, Smoyer WE. Drug prescribing in renal failure. Dosing guidelines for adults and children. Fifth edition. Philadelphia : ACP Vers Press ; 2007.
 Roberts DM, Sevastos J, Carland JE, Stocker SL, Lea-Henry TN. Clinical Pharmacokinetics in Kidney Disease: Application to Rational Design of Dosing Regimens. Clin J Am Soc Nephrol. 2018 Aug 7;13(8):1254-1263.
 Vidal L, Shavit M, Fraser A, Paul M, Leibovici L. Systematic comparison of four sources of drug information regarding adjustment of dose for renal function. BMJ 2005 ; 331(7511) : 263.
 Chertow GM, Lee J, Kuperman GJ, Burdick E, Horsky J, Seger DL, Lee R, Mekala A, Song J, Komaroff AL, Bates DW.Guided medication dosing for inpatients with renal insufficiency. JAMA 2001 ; 286(22) : 2839-44.
 Hug BL, Witowski DJ, Sox CM, Keohane CA, Seger DL, Yoon C, Matheny ME, Bates DW. Occurrence of adverse, often preventable, events in community hospitals involving nephrotoxic drugs or those excreted by the kidney. Kidney Int. 2009 ; 76(11) : 1192-8
 Makary MA, Daniel M. Medical error-the third leading cause of death in the US. BMJ. 2016 May 3;353:i2139.
 Cardinal H, Madore F. La pharmacopée de prévention cardiovasculaire est-elle sous utilisée chez le patient souffrant d’insuffisance rénale chronique après un infarctus du myocarde ? Nephrol & Therap 2010 ; 6(3) : 162-70.
 Swan SK. Diuretic strategies in patients with renal failure. Drugs 1994 ; 48(3) : 380-5
 Presne C, Monge M, Mansour J, Oprisiu R, Choukroun G, Achard JM, Fournier A. Diuretic-based therapy. Nephrol & Therap 2007 ; 3(6) : 392-426.
 Karie S, Launay-Vacher V, Deray G, Isnard-Bagnis C. Toxicité rénale des medicaments. Nephrol & Therap 2010; 6(1): 58-74.
 Perazella MA. Pharmacology behind Common Drug Nephrotoxicities. Clin J Am Soc Nephrol. 2018 Dec 7;13(12):1897-1908.
 Field TS, Rochon P, Lee M, Gavendo L, Baril JL, Gurwitz JH. Computerized clinical decision support during medication ordering for long-term care residents with renal insufficiency. J Amm Led Inform Assoc 2009 ; 16(4) : 480-5.
 Drug dosing consideration in patients with acute and chronic kidney disease - a clinical update from Kidney Disease : Improving Global Outcomes (KDIGO). Matzke GR, Aronoff GR, Atkinson AJ Jr, Bennett WM, Decker BS, Eckardt KU, Golper T, Grabe DW, Kasiske B, Keller F, Kielstein JT, Mehta R, Mueller BA, Pasko DA, Schaefer F, Sica DA, Inker LA, Umans JG, Murray P. Kidney Int. 2011 Dec;80(11):1122-37.
 Verbeeck RK, Musuamba FT. Pharmacokinetics and dosage adjustment in patients with renal dysfunction. Eur J Clin Pharmacol 2009 ; 65(8) : 757-73
 Ponticelli C, Graziani G. Management of drug toxicity in patients with renal insufficiency. Nat Rev Nephrol 2010 ; 6(6) : 317-8
 Laville SM, Gras-Champel V, Moragny J, Metzger M, Jacquelinet C, Combe C, Fouque D, Laville M, Frimat L, Robinson BM, Stengel B, Massy ZA, Liabeuf S, and on behalf of the Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) Study Group. Adverse Drug Reactions in Patients with CKD. Clin J Am Soc Nephrol. 2020 Jul 01. [Epub ahead of print]