Phloroglucinol-Derived Medications are Effective in Reducing Pain and Spasms of Urinary and Biliary Tracts: Results of Phase 3 Multicentre, Open-Label, Randomized, Comparative Studies of Clinical Effectiveness and Safety

Introduction: Pain and spasms of urinary and biliary tracts are conditions causing poor quality of life. Treatment with analgesic drugs such as non-steroidal anti-inflammatory drugs and modulators of the parasympathetic system are not always tolerated, and often additional therapeutic options are necessary. The present analysis aimed to evaluate the pharmacokinetics and effectiveness of oral and parenteral preparations based on phloroglucinol in reducing pain and spasms associated with renal or biliary colic in phase 3, multicentre, open-label, randomized, comparative studies on clinical effectiveness and safety.

Methods: Pharmacokinetic and pharmacodynamic studies were carried out. Four phase 3 multicentre, open-label, randomized, comparative studies were conducted to evaluate the clinical effectiveness and safety in patients with pain and spasms of urinary or biliary tracts. Eligible patients randomly received either phloroglucinol orally or via intramuscular (IM)/intravenous (IV) administration and reference drug, dexketoprofen for urinary spasms and pain, the non-steroidal anti-inflammatory drug metamizole or scopolamine-based reference drug for biliary colic. The primary outcomes were symptoms and observed frequency of spasms, while the secondary outcome was the duration of improvement or the time between the drug administration and the recurrence of symptoms. Comparison of groups by quantitative characteristics was performed using the T-test for independent samples or the Mann-Whitney test. Intragroup comparisons were performed using the Wilcoxon test, or the T-test for linked samples. Qualitative signs were analysed using the Pearson's χ² test and Fisher's exact test.

Results: The pharmacokinetic studies showed that (i) most of the phloroglucinol (> 80% for IV and per os formulations) was eliminated in the first 6 h after dosing, (ii) the drug was eliminated in urine as unchanged phloroglucinol (1,3,5-trihydroxybenzene) in a small proportion (< 3% of the dose) and (iii) a considerable amount of the drug was detected after enzymatic deconjugation with β-glucoronidase/arylsulfatase from Helix pomatia. As for the pharmacokinetic study, a total of 364 patients were enrolled, divided in four studies: two designed to test the effectiveness of oral and IM/IV preparations in biliary colic and two in urinary colic. Baseline characteristics between groups were similar. Phloroglucinol oral or IV/IM showed an effectiveness comparable to the reference drug in reducing pain and spasms associated with both urinary and biliary colic. There was no difference between all groups by survival analysis.

Conclusion: Oral and parenteral preparations based on phloroglucinol are as effective in reducing pain and spasms associated with renal or biliary colic as current therapeutic options. Therefore, phloroglucinol may be considered as useful to treat pain and spasms associated with urinary and biliary colic.