Nasal absorption of procyclidine in rats and dogs

Bioanalytical method for estimation of procyclidine in human plasma using liquid chromatography-tandem mass spectrometry: Application to pharmacokinetic study

A rapid, selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantification of procyclidine hydrochloride in human plasma using Procyclidine D11 hydrochloride as internal standard. Liquid-liquid extraction technique with methyl tertiary butyl ether was used for the extraction of plasma samples. Chromatographic separation of the analyte and the internal standard from the endogenous components was done on Zodiac C₁₈ column (50 × 4.6 mm, 5 µm) using a mixture of methanol and 0.1% formic acid in water (70:30, v/v) as mobile phase at a flow rate of 1 mL/min with the run time of 2 min. The detection of the eluents was done using multiple reaction monitoring (MRM) in positive ion mode. Linearity of the method was established in the concentration range of 0.5 to 120 ng/mL. Full validation of the method was done as per USFDA guidelines and the results were well within the acceptance limits. The successful application of the method was done on healthy human subjects under fasting conditions, proving it to be used for bioequivalence and bioavailability (BA/BE) studies of procyclidine.

Supralethal poisoning by any of the classical nerve agents is effectively counteracted by procyclidine regimens in rats

A treatment regimen consisting of HI-6, levetiracetam, and procyclidine (termed the triple regimen) has previously been shown to work as a universal therapy against soman poisoning in rats, since it has capacities to function as both prophylactic and therapeutic measure. The purpose of the present study was to examine whether the triple regimen may have antidotal efficacy against intoxication by other classical nerve agents than soman. The treatment was given 1 and 5 min after exposure to a supralethal dose of nerve agents, and the results showed that the triple regimen successfully prevented or terminated seizures and preserved the lives of rats exposed to 5×LD50 of soman, sarin, cyclosarin, or VX, but solely 3×LD50 of tabun was managed by this regimen. To meet the particular antidotal requirements of tabun, the triple regimen was reinforced with obidoxime and was made to a quadruple regimen that effectively treated rats intoxicated by 5×LD50 of tabun. The rats recovered very well and the majority gained pre-exposure body weight within 7 days. Neuropathology was seen in all groups regardless of whether the rats seized or not. The most extensive damage was produced by sarin and cyclosarin. Differentiation between the nerve agents' potency to cause lesions was probably seen because the efficacious treatments ensured survival of supralethal poisoning. A combination of 2 oximes and 2 anticonvulsants may be a prerequisite to counteract effectively high levels of poisoning by any classical nerve agent.

Intranasal delivery: physicochemical and therapeutic aspects

Interest in intranasal (IN) administration as a non-invasive route for drug delivery continues to grow rapidly. The nasal mucosa offers numerous benefits as a target issue for drug delivery, such as a large surface area for delivery, rapid drug onset, potential for central nervous system delivery, and no first-pass metabolism. A wide variety of therapeutic compounds can be delivered IN, including relatively large molecules such as peptides and proteins, particularly in the presence of permeation enhancers. The current review provides an in-depth discussion of therapeutic aspects of IN delivery including consideration of the intended indication, regimen, and patient population, as well as physicochemical properties of the drug itself. Case examples are provided to illustrate the utility of IN dosing. It is anticipated that the present review will prove useful for formulation scientists considering IN delivery as a delivery route.

Cognitive side effects in rats caused by pharmacological agents used to prevent soman-induced lethality

It is important that prophylactics used to protect military and emergency personnel against lethal doses of nerve agents do not by themselves produce impairment of cognitive capability. The purpose of the present study was to examine whether physostigmine, scopolamine, and various doses of procyclidine might reduce rats' innate preference for novelty. When these drugs were tested separately, the results showed that physostigmine (0.1 mg/kg) and procyclidine (3 mg/kg) did not affect preference for novelty, whereas scopolamine (0.15 mg/kg) and procyclidine in a higher dose (6 mg/kg) resulted in a preference deficit (Experiment 1). In Experiment 2, the combination of physostigmine and scopolamine or physostigmine and procyclidine (6 mg/kg) caused a marked deficit in preference for novelty. A much milder deficit was observed when physostigmine was combined with lower doses (1 or 3 mg/kg) of procyclidine. The latter combinations also had milder adverse impact on the animals' interest in the test environment and activity measures than the former combinations. By combining physostigmine with anticholinergics, a potentiation of adverse effects on behavior was seen. It is concluded that a slight cognitive impairment might be unavoidable with effective prophylactics.