Effectiveness of Oral Route Isosorbide 5-Mononitrate on Peritoneal Solute and Fluid Transports in CAPD Patients
Talerngsak Kanjanabuch MD*, Somchai Eiam-Ong MD*
Affiliation : * Division of Nephrology, Department of Medicine, King Chulalongkorn Memorial Hospital
Background : Addition of sodium nitroprusside (NaNTP), a nitric oxide (NO) donor, to peritoneal solution
could enlarge the effective peritoneal surface area and the peritoneal pore size. This would be leading to
increased clearance of all solutes. Generalized clinical usage of NaNTP in CAPD patients however is not
practical because it has a very short half-life and needs a specific route of administration. Organic nitrate,
another NO donor, has a longer half-life and could be more easily absorbed via many routes.
Objective : The present study was conducted to determine the effect and mechanism of oral active nitrate
(isosorbide 5-mononitrate: ISMN) on solute and fluid transports in stable CAPD patients.
(cid:31)
Materials and Methods : A prospective randomized placebo control with a crossover study was performed in
nine stable CAPD patients. In group 1 (n = 4), the treatment included 1) oral ISMN at the dose of 20 mg bid
for 5 days 2) wash out period for 7 days, and 3) placebo for 5 days. In group 2 (n = 5), the treatment regimens
were placebo, wash out, and ISMN periods.
Results : The MTACs of low molecular weight (LMW) solutes in the ISMN period were greater than the placebo
period: median urea, 16.7 vs 13.8 ml/min; creatinine (Cr), 7.9 vs 6.9 ml/min; and urate, 6.1 vs 5.5 ml/min (p <
0.05 for all except MTAC of urea). Administration of ISMN could also enhance the clearances of high molecu-
lar weight (HMW) solute with a magnitude of increase as follows: 10% for β2-microglobulin, 50% for albumin,
and 15% for immunoglobulin G (p < 0.05 for all). However, the values of restrictive coefficient of LMW as well
as HMW solutes of both groups were not different, indicating that the increased solute transports are not due
to alteration in the peritoneal membrane permeability. Despite the increased peritoneal solute clearance, net
ultra filtration (UF) was unchanged after drug administration, 110 (ISMN group) vs 120 ml (placebo group),
(NS).
Conclusion : ISMN has a similar effect as NaNTP in enhancing peritoneal clearances of both LMW and HMW
solutes. The effect of ISMN, however, is mediated only via expansion of peritoneal surface area without
significant change in pore size. As such, administration of oral ISMN to stable CAPD patients would be
practically beneficial in enhancing the achievement of target solute clearances suggested by NKF- DOQI
Guidelines.
Keywords : Isosorbide 5-mononitrate, MTAC, Peritoneal solute transport, Fluid transport, CAPD
