[Changes in Test Methods for Internationalization in the Japanese Pharmacopoeia (Part 1): Establishment of a Quantitative Test Method for Clonidine Hydrochloride Using HPLC Analysis]

The Japanese Pharmacopoeia (JP) is an official normative guide for maintaining the authenticity of properties and qualities of medicine in Japan. The JP is revised every 5 years, and partial amendments are made from time to time to keep abreast with progress in science and technology and international harmonization. We are conducting a related study on the elimination of toxic reagents from the JP. The elimination of toxic reagents is an important study in relation to the five pillars of the revision of the 18th JP, "Improvement in quality by proactively introducing the latest knowledge and technological advances". In addition, "Internationalization of the JP" is an important issue to be addressed during revision of the JP. Considering international harmonization of the JP, it is important to incorporate the test methods that have been used in other pharmacopoeia, such as the United States Pharmacopeia (USP) and the European Pharmacopoeia (EP) in the JP. To achieve the above, herein, we selected clonidine hydrochloride, which is listed in the 17th JP. A potentiometric titration method is used as a quantitative method for clonidine hydrochloride in the 17th JP; in contrast, a HPLC method is utilized in the USP and the EP. In this study, we synthesized impurities of clonidine hydrochloride and determined their purities using quantitative NMR. In addition, the complete separation conditions of these compounds by HPLC were examined, and simultaneous analysis was performed.

Medication Safety in Intravenous Therapy: A Compatibility Study of Clonidine with Drugs Frequently Used in Intensive Care

The intravenous pharmacotherapy of critically ill patients is extremely challenging due to the high number of drugs administered. We therefore evaluated the physicochemical compatibility of combinations of clonidine with drugs frequently used in an intensive care unit setting. Amiodarone, dihydralazine, furosemide, levosimendan, metamizole, milrinone, urapidil, and verapamil were each prepared as binary combinations with clonidine at the standard low and high administration concentrations. Selected ternary combinations were also analyzed. Samples were examined for physical compatibility. To verify chemical compatibility in samples deemed either physically compatible or to exhibit uncertain results, the drug content was quantified using high-performance liquid chromatography. Admixtures of clonidine with amiodarone or furosemide proved to be physically incompatible, whereas mixtures with levosimendan and metamizole exhibited results, which were not clearly meeting the specification criteria for physical compatibility. Binary combinations of clonidine with dihydralazine, milrinone, urapidil, and verapamil were found to be physically compatible. Combinations with dihydralazine, levosimendan, metamizole, milrinon, urapidil, or verapamil were chemically compatible for the analyzed concentrations. Ternary admixtures of clonidine, metamizole, and urapidil; clonidine, metamizole, and verapamil; clonidine, urapidil, and verapamil were shown to be physicochemically compatible for the analyzed concentrations. These data suggest that clonidine can be coadministered with dihydralazine, levosimendan, metamizole, milrinone, urapidil, and verapamil. However, the concomitant administration of clonidine with amiodarone or furosemide is not recommended.

3D-Printed Wearable Personalized Orthodontic Retainers for Sustained Release of Clonidine Hydrochloride

Orthodontic retainers are wearable customizable medical devices for dental protection or alignment. Here, clonidine hydrochloride (CH)-loaded wearable personalized 3D printed orthodontic retainers were studied for local sustained-release of drugs. CH powders were mixed with PEG 4000, Tween 80, poly(lactic acid), and polycaprolactone. The mixture was hot-melt extruded to form a filament that was 3D printed to a customizable original orthodontic retainer with the fused deposition modeling (FDM) method. The original retainer showed a burst release of CH in the early stage of the dissolution process though a sustained release appeared in the late stage. The in vivo burst release of CH would lead to unexpected side effect. The original retainer was modified by coating with hydrophilic polymers or washing with buffered solutions to obtain the coated or washed retainer. The coated retainer still showed a burst release while the washed retainer showed an optimal sustained release. Many CH microparticles existed on the surface of original retainers according to the scanning electron microscopic image so that the burst release was unavoidable. The hydrophilic polymer coating method did not change the release profile because the polymer was also rapidly dissolved. However, most of the surface CH can be eliminated by washing so that the burst release dissappeared in the washed retainer. Furthermore, the simulated CH concentration-time profiles in the circulation of humans of the washed retainer showed the stable and appropriate drug levels for more than 3 days. Wearable personalized 3D printed drug-loaded orthodontic retainers are a promising drug-device for sustained release of drugs.

Evaluation of the Hemodynamic Response of Intravenous Clonidine versus Ropivacaine Scalp Block to Insertion of Scalp Pins in Neurosurgical Patients

Background:

The application of the skull-pin head-holder, used to stabilize the head during neurosurgical procedures, produces an intense nociceptive stimulus and results in abrupt increases in blood pressure and cerebral blood flow under general anesthesia. Different anesthetic and pharmacologic techniques, including local anesthetics, narcotics, antihypertensives, and deepening of anesthesia with inhalation anesthetics, have been used to blunt this deleterious effect with variable success.

Aim:

To compare the analgesic and hemodynamic effects of ropivacaine scalp block, and intravenous (IV) clonidine in attenuating the hemodynamic response to the scalp pin insertion in neurosurgical patients.

Settings and Design:

A comparative two group's clinical study of 64 patients undergoing elective craniotomy in Department of Anaesthesiology, Bangalore Medical College and Research Institute.

Methodology:

Sixty-four patients were allocated into any one of two groups of 32 patients each, by means of computer-generated randomization: (1) Group S: Patients receiving scalp block with injected ropivacaine 0.25% 30 ml. (2) Group C: Patients receiving 2 μg/kg IV clonidine.

Statistical Methods:

Descriptive and inferential statistical analysis has been carried out in the present study. Results on continuous measurements are presented on mean ± standard deviation (minimum–maximum) and results on categorical measurements are presented in number (%). Significance is assessed at 5% level of significance.

Results:

Increase in heart rate and blood pressure during pin insertion was attenuated by clonidine hydrochloride (P < 0.001). The number of patients who required more fentanyl and propofol to stabilize the hypertensive response were more in control group than clonidine group.

Conclusion:

IV clonidine maximally attenuated the hemodynamic response to application of head pins in a dose of 2 μg/kg compared to ropivacaine scalp block, thus maintaining intracranial pressure for neurosurgical anesthesia.

The role of α₂ adrenoceptor in mediating noradrenaline action in the ventrolateral orbital cortex on allodynia following spared nerve injury

The present study examined the role of α₂ adrenoceptor in mediating noradrenaline action in the ventrolateral orbital cortex (VLO) on allodynia induced by spared nerve injury (SNI) in the rat. The mechanical paw withdrawal threshold (PWT) was measured using von-Frey filaments. Microinjection of noradrenaline (1, 2, 4 μg in 0.5 μl) into the VLO, contralateral to the site of nerve injury, reduced allodynia; PWT increased in a dose-dependent manner. Similar to noradrenaline, microinjection of selective α₂ adrenoceptor agonist clonidine into the same VLO site also reduced allodynia, and was blocked by selective α₂ adrenoceptor antagonist yohimbine. Furthermore, administration of γ-aminobutyric acid A (GABAA) receptor antagonist bicuculline or picrotoxin to the VLO significantly enhanced clonidine-induced inhibition of allodynia, while GABAA receptor agonist muscimol or THIP (2,5,6,7-retrahydroisoxazolo(5,4-c)pyridine-3-ol hydrochloride) attenuated clonidine-induced inhibition. These results suggest that noradrenaline acting in the VLO can potentially reduce allodynia induced by SNI, and this effect is mediated by α₂ adrenoceptor. Moreover, GABAergic disinhibition may participate in α₂ receptor mediating effects in neuropathic pain in the central nervous system.

Implication of enterohepatic re-circulation on single dose bioequivalence evaluation of two brands of clonidine hydrochloride tablets in healthy human volunteers

A single dose, crossover bioequivalence study of two different brands of clonidine hydrochloride 25 μg tablets was conducted in 24 (+2 stand by) healthy, adult, male, Indian subjects under fasting conditions to check the implication of enterohepatic re-circulation on assessment of bioequivalence. After an overnight fasting of at least 10 h, the subjects received single oral dose of test or reference product with either of the product as per randomization schedule in each period with a washout period of 10 days. The pre-dose blood sample was collected within a period of one h before dosing. The post-dose blood samples were collected at specified time intervals up to 96 h. The plasma concentrations of clonidine were quantified by validated LCMS/MS method and pharmacokinetic parameters were computed. The 90% confidence intervals of test/reference ratios for C_max and area under the plasma-concentration- time-curve AUC under 0-t were found to be between 0.80 and 1.25 for log-transformed data. Analysis of variance did not show significant difference to these parameters. No meaningful values of K_el and therefore AUC under 0-infinity could be calculated for significant number of subjects due to enterohepatic re-circulation. Based on the results obtained, two different brands of clonidine 25 μg tablets have comparable rate and extent of absorption after oral administration but failed to show bioequivalence as per regulatory requirement of Food and Drugs Administration-united states.