Oral L-Arginine for Interstitial Cystitis
October 1, 1999 2 minutes read
Oral L-Arginine for Interstitial Cystitis
Abstract & commentary
Synopsis: Oral L-arginine may decrease pain and urgency in a subset of interstitial cystitis patients.
Source: Korting GE, et al. J Urol 1999;161:558-565.
Nitric oxide synthase activity is decreased in the urine of patients with interstitial cystitis. In a preliminary trial, oral L-arginine, the substrate for nitric oxide synthase, increased urinary nitric oxide synthase activity and improved interstitial cystitis symptoms.
A total of 53 interstitial cystitis patients were randomly assigned to receive daily 1500 mg L-arginine or placebo orally for three months. Interstitial cystitis symptoms were assessed by interviews at two weeks, and one, two, and three months. The trial was completed by 21 of 27 patients in the L-arginine group and 25 of 26 in the placebo group. Using per protocol analysis, 6/21 (29%) patients in the L-arginine group and 2/25 (8%) in the placebo group were clinically improved by the end of the trial (P = 0.07). A Likert scale showed greater global improvement in the L-arginine group (10/21, 48%) than in the placebo group (6/25, 24%) at three months (P = 0.05) with a decrease in pain intensity (P = 0.04), and tendency toward improvement in urgency (P = 0.05) and frequency of pain (P = 0.09). Using an intention to treat approach, there were no differences between the groups.
The investigators conclude that oral L-arginine may decrease pain and urgency in a subset of interstitial cystitis patients.
Comment By John La Puma, Md, FACP
A successful pilot study with more hands-on attention than their intervention helped Korting and colleagues to gain NIH support for this double-blind investigation. Only after three months was there a demonstrable difference between L-arginine and placebo patients. Patients with greater than 800 cc bladder capacity and a history of recurrent genitourinary infections were the two subgroups that experienced improvement. Adverse effects were not described, although four of the six or seven (per Korting et al) who withdrew from the arginine group complained of increased pain, not decreased pain.
Oral L-arginine is also touted for nonobstructive coronary disease. It seems to have beneficial effects, but also "has been reported to activate herpes virus replication and interact, in animal models, with tumor growth."
In patients with interstitial cystitis refractory to standard measures who are willing to risk actually increased pain, who are not immunosuppressed, and who do not have a history of herpes activation, oral L-arginine may be worth a try. If it does work, it will probably take three months. Be cautious.
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