Phase I, Single-Dose Study to Assess the Pharmacokinetics and Safety of Suramin in Healthy Chinese Volunteers.

Purpose: Suramin is a multifunctional molecule with a wide range of potential applications, including parasitic and viral diseases, as well as cancer. Methods: A double-blinded, randomized, placebo-controlled single ascending dose study was conducted to investigate the safety, tolerability, and pharmacokinetics of suramin in healthy Chinese volunteers. A total of 36 healthy subjects were enrolled. All doses of suramin sodium and placebo were administered as a 30-minute infusion. Blood and urine samples were collected at the designated time points for pharmacokinetic analysis. Safety was assessed by clinical examinations and adverse events. Results: After a single dose, suramin maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from time zero to the time of the last measurable concentration (AUClast) increased in a dose-proportional manner. The plasma half-life (t1/2) was dose-independent, average 48 days (range 28-105 days). The cumulative percentages of the dose excreted in urine over 7 days were less than 4%. Suramin can be detected in urine samples for longer periods (more than 140 days following infusion). Suramin was generally well tolerated. Treatment-emergent adverse events (TEAEs) were generally mild in severity. Conclusion: The PK and safety profiles of suramin in Chinese subjects indicated that 10 mg/kg or 15 mg/kg could be an appropriate dose in a future multiple-dose study.

Bladder tissue pharmacokinetics of intravesical mitomycin C and suramin in dogs.

Suramin, at non-cytotoxic doses, reverses chemoresistance and enhances the activity of mitomycin C (MMC) in mice bearing human bladder xenograft tumors. The present study evaluated the pharmacokinetics of the intravesical suramin and MMC, alone or in combination, in dogs. Animals received either high dose suramin (20 mg/ml), low dose suramin (6 mg/ml), MMC (2 mg/ml), or combination of low dose suramin and MMC, instilled for 2 h. The dosing volume was 20 ml. All groups showed dilution of drug levels over time due to continued urine production. For single agent suramin, the results showed (a) 5% to 10% penetration into bladder tissues, (b) minimal and clinically insignificant systemic absorption (i.e., undetectable at low dose or a peak concentration that was 6,000× lower than urine concentrations), and (c) disproportionally higher drug penetration and concentrations in bladder tissues at the higher dose. Results for single agent MMC are consistent with our earlier observations. The co-administration of MMC did not alter the plasma, urine, or tissue pharmacokinetics of suramin. Adding suramin did not alter plasma or tissue pharmacokinetics of MMC, but lowered the MMC concentrations in urine by about 20%. This may be in part due to accelerated MMC degradation by co-incubation of suramin or due to variations in urine production rate (because animals were allowed for water during treatment). Suramin readily penetrates the urothelium and into deeper bladder tissues, indicating its potential utility in intravesical therapy.