Drotaverine (hydrochloride)

Drotaverine hydrochloride is a type 4 cyclic nucleotide phosphodiesterase (PDE4) inhibitor and an L-type voltage-dependent calcium channel (L-VDCC) blocker, blocks the degradation of 3',5'-cyclic adenosine monophosphate. Drotaverine (hydrochloride) exhibits in vivo antispasmodic efficacy without anticholinergic effects. In Vitro:Drotaverine hydrochloride is a relaxant for pre-contracted airways that shows concentration-dependent and medium-dependent effects. The ED ₅₀ for histamine, methacholine, and potassium chloride as contractile agents are 4.7×10^-5, 4.3×10^-5, and 2.2×10^-5 mol/L^[1].
Drotaverine hydrochloride suppresses bronchial contractions in guinea pigs, with ED ₅₀ values for histamine, methacholine, and potassium chloride being 8.5×10^-5, 9.3×10^-5, and 7.4×10^-5 mol/L^[1].
Drotaverine hydrochloride shows higher selectivity for KCl-induced contractions^[1].
Drotaverine hydrochloride inhibits the specific binding of nifedipine and diltiazem, with IC₅₀ values of 5.6 and 2.6 μM^[2].
Drotaverine hydrochloride significantly increases the dissociation rate constants (k^-1 (min^-1)) for nifedipine and diltiazem from the uterine membranes of pregnant rats to 0.055 and 0.062, respectively, with corresponding half-lives (t_1/2 (min)) of 5.55 and 4.9^[2]. In Vivo:Drotaverine (10-80 mg/kg, i.p., single dose) hydrochloride improves cognitive impairment and shows the ability to regulate levels of neurotransmitters in the brain^[3].