Effects of D-004, a lipid extract from the royal palm (Roystonea regia) fruits, tamsulosin and their combined use on urodynamic changes induced with phenylephrine in rats.

5-alpha-Reductase inhibitors, alpha1-adrenoreceptors blockers and herbal drugs, like lipid extracts from saw palmetto fruits, are used to treat benign prostatic hyperplasia (BPH). D-004, a lipid extract from the Royal palm fruits, prevented prostate hyperplasia (PH) induced with testosterone and the atypical PH induced with phenylephrine (PHE) in the rat, its effect in this last model being comparable to that of saw palmetto, but lesser than that of tamsulosin (CAS 106133-20-4). It was investigated whether single doses of D-004, tamsulosin and their combined therapy can prevent urodynamic changes induced with PHE in the rat. Firstly, the effects of PHE on rat volume voided per micturition (VM) were explored in rats that were distributed in three groups: a negative control and two groups injected s. c. with PHE (5 and 10 mg/kg, respectively). In the other two experiments, rats were distributed in four groups: a negative control and three groups injected with PHE (a positive control and two groups treated with either tamsulosin 0.05 and 0.1 mg/kg, or D-004 400 and 800 mg/kg. In another experiment, the effects of the combined therapy were assessed using four groups: a negative control, a positive control and three groups treated orally with tamsulosin 0.05 mg/kg, D-004 400 mg/kg or D-004 400 mg/kg + tamsulosin 0.05 mg/kg, respectively. Sixty min later, all rats (except negative controls) were injected s. c. with PHE (5 mg/kg), and all (including the negative controls) received a fluid-loading dose. Thirty min later, they were placed in metabolic cages and theVM was measured for 1 h. The VM was significantly reduced with PHE (5 and 10 mg/kg), the high dose producing anuria in 50% of the rats. The reduction of VM was significantly and dose-dependently prevented with tamsulosin (0.05 and 0.1 mg/kg) (42.9% and 60.3%, respectively) and with D-004 (400 and 800 mg/kg) (25.2% and 43.1%, respectively). The inhibition reached (70.9%) with the combined therapy was greater than that reached with each monotherapy and also greater than the sum (56.8%) of the inhibitions reached with tamsulosin (35%) or D-004 (21.8%) alone. In conclusion, tamsulosin (0.05 and 0.1 mg/kg) and D-004 (400-800 mg/kg) dose-dependently inhibited the VM reduction induced with PHE, their combined therapy producing the greater effects.