General
Pentosan polysulfate sodium is a low molecular weight heparin-like compound.
It has anticoagulant and fibrinolytic effects. The mechanism of action of pentosan
polysulfate sodium in interstitial cystitis is not known.
Pharmacokinetics
Absorption: In a clinical pharmacology study in which healthy
female volunteers received a single oral 300 or 450 mg dose of pentosan polysulfate
sodium containing radiolabeled drug as a solution under fasted conditions, maximal
levels of plasma radioactivity were seen approximately at a median of 2 hours
(range 0.6-120 hours) after dosing. Based on urinary excretion of radioactivity,
a mean of approximately 6% of a radiolabeled oral dose of pentosan polysulfate
sodium is absorbed and reaches the systemic circulation.
Food Effects: In clinical trials, ELMIRON® was administered
with water 1 hour before or 2 hours after meals; the effect of food on absorption
of pentosan polysulfate sodium is not known.
Distribution: Preclinical studies with parenterally administered
radiolabeled pentosan polysulfate sodium showed distribution to the uroepithelium
of the genitourinary tract with lesser amounts found in the liver, spleen, lung,
skin, periosteum, and bone marrow. Erythrocyte penetration is low in animals.
Metabolism: The fraction of pentosan polysulfate sodium that
is absorbed is metabolized by partial desulfation in the liver and spleen, and
by partial depolymerization in the kidney to a large number of metabolites.
Both the desulfation and depolymerization can be saturated with continued dosing.
Excretion: Following administration of an oral solution of a
300 or 450 mg dose of pentosan polysulfate sodium containing radiolabeled drug
to groups of healthy subjects, plasma radioactivity declined with mean half-lives
of 27 and 20 hours, respectively. A large proportion of the orally administered
dose of pentosan polysulfate sodium (mean 84% in the 300 mg group and 58% in
the 450 mg group) is excreted in feces as unchanged drug. A mean of 6% of an
oral dose is excreted in the urine, mostly as desulfated and depolymerized metabolites.
Only a small fraction of the administered dose (mean 0.14%) is recovered as
intact drug in urine.
Special Populations
The pharmacokinetics of pentosan polysulfate sodium has not been studied in
geriatric patients or in patients with hepatic or renal impairment. See also
PRECAUTIONS - Hepatic Insufficiency.
Drug-Drug Interactions
In a study in which healthy subjects received pentosan polysulfate sodium
100 mg capsule or placebo every 8 hours for 7 days, and were titrated with warfarin
to an INR of 1.4 to 1.8, the pharmacokinetic parameters of R-warfarin and S-warfarin
were similar in the absence and presence of pentosan polysulfate sodium. INR
for warfarin + placebo and warfarin + pentosan polysulfate sodium were comparable.
See also PRECAUTIONS on the use of ELMIRON®
in patients receiving other therapies with anticoagulant effects.
Pharmacodynamics
The mechanism by which pentosan polysulfate sodium achieves its effects in patients is unknown. In preliminary clinical models, pentosan polysulfate sodium adhered to the bladder wall mucosal membrane. The drug may act as a buffer to control cell permeability preventing irritating solutes in the urine from reaching the cells.
Clinical Trials
ELMIRON® was evaluated in two clinical trials for the relief of pain in patients with chronic interstitial cystitis (IC). All patients met the NIH definition of IC based upon the results of cystoscopy, cytology, and biopsy. One blinded, randomized, placebo controlled study evaluated 151 patients (145 women, 5 men, 1 unknown) with a mean age of 44 years (range 18 to 81). Approximately equal numbers of patients received either placebo or ELMIRON® 100 mg three times a day for 3 months. Clinical improvement in bladder pain was based upon the patient's own assessment. In this study, 28/74 (38%) of patients who received ELMIRON® and 13/74 (18%) of patients who received placebo, showed greater than 50% improvement in bladder pain (p=0.005).
A second clinical trial, the physician's usage study, was a prospectively designed retrospective analysis of 2499 patients who received ELMIRON® 300 mg a day without blinding. Of the 2499 patients, 2220 were women, 254 were men, and 25 were of unknown sex. The patients had a mean age of 47 years and 23% were over 60 years of age. By 3 months, 1307 (52%) of the patients had dropped out or were ineligible for analysis, overall, 1192 (48%) received ELMIRON® for 3 months; 892 (36%) received ELMIRON® for 6 months; and 598 (24%) received ELMIRON® for one year.
Patients had unblinded evaluations every 3 months forthe patient's rating of overall change in pain in comparison to baseline and for the difference calculated in "pain/discomfort" scores. At baseline, pain/discomfort scores forthe original 2499 patients were severe or unbearable in 60%. moderate in 33% and mild or none in 7% of patients. The extent of the patients' pain improvement is shown in Table 1.
At 3 months, 722/2499 (29%) of the patients originally in the study had pain scores that improved by one or two categories. By 6 months, in the 892 patients who continued taking ELMIRON®, an additional 116/2499 (5%) of patients had improved pain scores. After 6 months, the percent of patients who reported the first onset of pain relief was less than 1.5% of patients who originally entered in the study (see Table 2).
Table 1: Pain Scores in Reference to Baseline in Open Label
Physician's Usage Study (N=2499)1
| Efficacy Parameter |
3 months2 |
6 months2 |
| Patient Rating of Overall Change in Pain (Recollection of difference
between current pain and baseline pain)3 |
N=1161
Median=3
Mean=3.44
CI: (3.37, 3.51) |
N=724
Median=4
Mean=3.91
CI: (3.83, 3.99) |
| Change in Pain/Discomfort Score (Calculated difference in scores at
the time point and baseline)4 |
N=1440
Median=1
Mean=0.51
CI: (0.45, 0.57) |
N=904
Median=1
Mean=0.66
CI: (0.61, 0.71) |
1Trial not designed to detect onset of pain
relief
2CI = 95% confidence interval
36-point scale: 1 = worse, 2 = no better; 3 = slightly improved,
4 = moderately improved. 5 = greatly improved, 6 = symptom gone
43-point scale: 1 = none or mild, 2 = moderate, 3 = severe
or unbearable |
Table 2: Number (%) of Patients with New Relief of Pain/Discomfort1
in the Open-Label Physician's Usage Study (N=2499)
| |
at 3 months2 (n=1192) |
at 6 months3 (n=892) |
| Considering only the patients who continued treatment |
722/1192 (61%) |
116/892 (13%) |
| Considering all the patients originally enrolled in the study |
722/2499 (29%) |
116/2499 (5%) |
1First-time Improvement in pain/discomfort score
by 1 or 2 categories
2Number (%) of patients with improvement of pain/discomfort score
at 3 months when compared to baseline
3Number (%) of patients without pain/discomfort improvement at 3
months who had improvement at 6 months |
Last updated on RxList: 2/4/2009