Mechanism of smooth muscle relaxation by tiropramide

Quantitative analysis of tiropramide in human plasma by gas chromatography coupled to mass spectrometry for application to a bioequivalence test

BACKGROUND

Tiropramide is used as an antispasmodic agent. A sensitive, selective and simple gas chromatography coupled to mass spectrometry (GC/MS) was developed for quantification of tiropramide in human plasma using internal standard (ISD, (+/-) alpha-benzoylamino-4-[2-(dimethylamino) ethoxy]-N,N-dipropylbenzenepropanamide).

METHODS

Tiropramide and ISD were extracted from plasma by solid-liquid extraction and analyzed on a HP-5MS column with mass selective detector.

RESULTS

The retention times of tiropramide and ISD were approximately 9.8 and 10.2 min, respectively. The calibration curve showed good linearity in the concentration range 5-500 ng/ml (r2=0.998) for tiropramide in human plasma and showed good precision with CVs between 0.24% and 7.69%, respectively. The method was showed good accuracy with all intra-day (n=5) and inter-day (n=5) mean concentrations within 87.9-114.1% from nominal. The recovery of tiropramide and ISD were about 75.1% and 71.0% on the average, respectively. This method was successfully applied for the bioequivalence test of 2 formulations of tiropramide in 18 healthy male volunteers who received a single 100 mg dose of each formulation.

Quantitative analysis of tiropramide in human blood by gas chromatography with nitrogen-phosphorus detector

The analytical method of antispasmodic agent tiropramide ((+/-)alpha-(benzoylamino)-4-[2-(diethylamino)ethoxy]-N,N-dipropylbenzenepropanamide hydrochloride) was developed by gas chromatography/nitrogen-phosphorus detector (GC/NPD) in human plasma. Two kinds of tiropramide tablets were orally administered to volunteers by Latin square crossover design, and blood was withdrawn as designed schedule. The plasma of 1 mL was loaded on Sep-pak C18 cartridge and eluted with methanol after washing with 30% methanol. The residue dissolved in 100 microL of methanol after evaporation was analyzed by GC/NPD. Precision (CV%) of intra-day was located within 2.6% and accuracy was less than 9.7%. Inter-day precision was below 8.7% and accuracy was relatively good as less than 14%. Plasma samples obtained from human volunteers were analyzed for the determination of tiropramide concentration by using this method. The method was sensitive, rapid and suitable enough to be applied for pharmacokinetic and bioequivalence studies of tiropramide in human volunteers.

Functional gut disorders: from motility to sensitivity disorders. A review of current and investigational drugs for their management

Functional gut disorders include several clinical entities defined on the basis of symptom patterns (e.g., functional dyspepsia, irritable bowel syndrome, functional abdominal pain, functional abdominal bloating), for which there is no established pathophysiological mechanism. Because there is no well-defined pathophysiological target, treatment should be aimed at symptom improvement. Prokinetics and antispasmodics have been widely used in the treatment of functional gut disorders on the assumption that disordered motility is the underlying cause of symptoms, and symptom improvement is indeed achievable with these compounds in some, but not all, patients with features of hypo- or hypermotility, respectively. In the first part of this review, we cover the basic pharmacology and discuss the rationale for the clinical use of prokinetics and antispasmodics. On the other hand, in the past few years, the explosive growth in the research focusing on visceral sensitivity and visceral reflexes has suggested that at least some patients with functional gut disorders have altered visceral perception. Thus, the second part of the review covers these developments and focuses on studies addressing the issue of drugs modulating visceral sensitivity.

Pharmacological properties of tiropramide, an antispasmodic drug

1. The pharmacological properties of an antispasmodic drug, tiropramide, were studied in isolated smooth muscle preparations. 2. Tiropramide at concentrations of 10(-6) to 10(-4) M relaxed various smooth muscles contracted spontaneously and by smooth muscle stimulants or electrical stimulation. Tiropramide did not interact with all drug-receptors examined, suggesting a pure musculotropic smooth muscle relaxant activity. 3. Tiropramide was found to inhibit both Ca uptake and Ca release in the guinea pig urinary bladder. 4. Tiropramide is considered to be useful to inhibit the contractile response of the urinary bladder, as this organ is mainly innervated by noncholinergic excitatory neurons.