title: The acute effect of beta-guanidinopropionic acid versus creatine or placebo in healthy men (ABC Trial): study protocol for a randomized controlled trial.
abstract: BACKGROUND
  Despite adequate treatment, up to 30% of treated antihypertensive patients with primary, uncomplicated hypertension remain uncontrolled. We proposed that high intracellular activity of the ATP regenerating enzyme creatine kinase (CK) increases pressor responses and hypertension risk. In line with this, we found that plasma CK activity after rest, a surrogate measure of tissue activity, is the main predictor of blood pressure levels and failure of antihypertensive therapy in the general population. In addition, the creatine analog and competitive oral creatine kinase inhibitor beta-guanidinopropionic acid effectively and safely reduced blood pressure in the spontaneously hypertensive rat. However, to our knowledge there are no human data on the safety of oral supplementation with this substance. Therefore, we will assess the tolerability of beta-guanidinopropionic acid in men, compared to creatine and placebo.
  
  
  METHODS
  This is a randomized, active and placebo controlled, triple blind, double dummy, single center clinical intervention trial in 24 healthy male volunteers, 18 to 50 years old, recruited in the Netherlands. The intervention consists of one week of daily oral administration of beta-guanidinopropionic acid 100 mg, creatine 5 gram, or placebo. The primary outcome is the tolerability of beta-guanidinopropionic acid as a descriptive measure, in an intent-to-treat analysis. Other outcomes include the placebo-adjusted differences with baseline in biochemical and hemodynamic parameters, including plasma markers of muscle tissue damage, urine sodium excretion, resting sitting systolic and diastolic brachial blood pressure, supine systolic and diastolic central blood pressure, pulse wave velocity and augmentation index, heart rate, cardiac contractility, cardiac output, and total peripheral resistance.
  
  
  CONCLUSIONS
  There is an unfulfilled need for new conservative options to treat resistant hypertension. This study will provide first-in-men data on creatine kinase inhibition as a potential new class of antihypertensive drugs.
  
  
  BACKGROUND
  The Netherlands National Trial Register Trialregister.nl (identifier NTR 4444) , registered 9 March 2014.
authors.affiliation: Department of Vascular Medicine, Room F4-253, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands. f.a.karamat@amc.nl.
authors.forename: Fares A
authors.initials: FA
authors.lastname: Karamat
authors.affiliation: Department of Vascular Medicine, Room F4-253, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands. d.l.horjus@amc.nl.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Horjus
authors.affiliation: Department of Vascular Medicine, Room F4-253, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands. y.c.haan@amc.nl.
authors.forename: Yentl C
authors.initials: YC
authors.lastname: Haan
authors.affiliation: Department of Vascular Medicine, Room F4-253, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands. l.vanderwoude@amc.nl.
authors.forename: Lisa
authors.initials: L
authors.lastname: van der Woude
authors.affiliation: Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. i.oudman@amc.nl.
authors.forename: Inge
authors.initials: I
authors.lastname: Oudman
authors.affiliation: Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. g.vanmontfrans@amc.nl.
authors.forename: Gert A
authors.initials: GA
authors.lastname: van Montfrans
authors.affiliation: Department of Neurology, Cincinnati Children's Hospital, 3333 Burnet Ave, Cincinnati, Ohio, USA. joseph.clark@uc.edu.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Clark
authors.affiliation: Department of Vascular Medicine, Room F4-253, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands. l.m.brewster@amc.nl.|Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. l.m.brewster@amc.nl.|Department of Social Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands. l.m.brewster@amc.nl.
authors.forename: Lizzy M
authors.initials: LM
authors.lastname: Brewster
mesh_terms: D000293:Adolescent; D000328:Adult; D002985:Clinical Protocols; D003401:Creatine / Q000627:therapeutic use*; D003402:Creatine Kinase / Q000037:antagonists & inhibitors* / Q000097:blood; D004311:Double-Blind Method; D004562:Electrocardiography; D006146:Guanidines / Q000627:therapeutic use*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D019055:No-Observed-Adverse-Effect Level; D011422:Propionates / Q000627:therapeutic use*
chemical_list: D006146:Guanidines; D011422:Propionates; D003402:Creatine Kinase; D003401:Creatine; C005775:guanidinopropionic acid