Key result
Doxorubicin was stable in acidic urine but degraded at alkaline pH, with 77% recovery following 1 hour's retention in the bladder regardless of dose.
Why the study?
Does urine pH affect the stability and recovery of doxorubicin during bladder instillations?
Does urine pH affect the stability and recovery of doxorubicin during bladder instillations?
Buffering intravesical doxorubicin to an acidic pH or pre-dosing patients with ammonium chloride may minimize loss of active drug during bladder retention.
Answers are grounded in this paper and cite their sources.
May support acidic pH buffering for intravesical doxorubicin; hypothesis-generating for clinical efficacy and safety.
Doxorubicin (1 mg/ml) was shown to be stable when added to urine samples with a mean natural pH of 5.4 and in urine buffered to a mean pH of 4.6. However, at alkaline pH (mean = 8.1) there was a biphasic degradation of doxorubicin (mean t1/2 = 3.24 and 89 h respectively). The data indicate that buffering intravesical doxorubicin to pH 4.6 (acetate buffer) or pre-dosing of patients with ammonium chloride may minimise loss of active drug during the time for which the drug is retained in the bladder. Recovery of doxorubicin following 1 hour's retention in the bladder was similar (77%) for doses of 38/48 or 78 mg. It is suggested that a dose of 50 mg (1 mg/ml) is sufficient to ensure an adequate delivery of active drug to the bladder wall.
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Ilett et al. (1990) studied this question. Doxorubicin was evaluated on Recovery of doxorubicin. Doxorubicin was stable in acidic urine but degraded at alkaline pH, with 77% recovery following 1 hour's retention in the bladder regardless of dose.
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