• Archives of Pharmacal Research
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• v.8 no.3
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• pp.177-186
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• 1985

Effect of food on the absorption characteristics of oral rifampicin was studied in the fasted rats. Rifampicin dissolved in a new cosolvent was also injected to the rats intravenously, and the pharmacokinetic analysis was performed to explain the effect of food on the gastrointestinal absorption of rifampicin. Rifampicin was absorbed rapidly and completely in the fasting state. Food had a profound effect on the gastrointestinal absorption of rifampicin, i. e., bioavailability and the extent of absorption were decreased to less than one-third of the fasting state in the postprandial state. Food seemed to imhibit the absorption and reabsorption of rifampicin in the gastrointestinal tract, but not the absorption rate constant. Hepatobiliary excretion seemed to be the major route of elimination, since the renal clearance accounted for only 8 % of the systemic clearance. Nevertheless, first-pass effect was negligibly small and most of rifampicin absorbed could reach systemic circulation. Serum concentration change of oral rifampicin on multiple dosing differed markedly in the fasting and postprandial state, which suggested the need of careful adjustment of dosage regimen in both states.

• Biomolecules & Therapeutics
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• v.17 no.3
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• pp.299-304
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• 2009

Rosiglitazone maleate (RGM) is widely used for improving insulin resistance. RGM is a moderate inhibitor of cytochrome P450 2C8 (CYP2C8) and is also mainly metabolized by CYP2C8. The aim of this study was to determine whether the effect of RGM on CYP2C8 is altered by co-treatment with other drugs, and whether amlodipine camsylate (AC) changes the pharmacokinetics (PK) of RGM. Of the 11 drugs that are likely to be co-administered with RGM in diabetic patients, seven drugs lowered the $IC_{50}$ value of RGM on CYP2C8 by more than 80%. In vitro CYP2C8 inhibitory assays of RGM in combination with drugs of interest showed that the $IC_{50}$ of RGM was decreased by 98.9% by AC. In a pharmacokinetic study, Sprague-Dawley (SD) rats were orally administered 1 mg/kg of RGM following by single or 10-consecutive daily administrations of 1.5 mg/kg/day of AC. No significant changes in the pharmacokinetic parameters of RGM were observed after a single administration of AC, but the AUC and $C_{max}$ values of RGM were significantly reduced by 36% and 31%, respectively, by multiple administrations of AC. In conclusion, RGM was found to be affected by AC by in vitro CYP2C8 inhibition testing, and multiple dosing of AC appreciably changed the pharmacokinetics of RGM. These findings suggest that a drug interaction exists between AC and RGM.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.23 no.2
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• pp.111-118
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• 2012

Botulinum toxin is a potent neurotoxin that is produced by the bacterium Clostridium botulinum. The agent causes muscle paralysis by preventing the release of acetylcholine at the neuromuscular junction of striated muscle. Botulinum toxin A (Botox, AllerganInc., Irvine, California) is the most potent of seven distinct toxin subtypes that are produced by the bacterium. The toxin was initially used clinically in the treatment of strabismus caused by hypertonicity of the extraocular muscles and was sub-sequently described in the treatment of multiple disorders of muscular spasticity and dystonia. In treating patients with Botox for blepharospasm, Carruthers and Carruthers [5] noticed an improvement in glabellar rhytids. This ultimately led to the introduction and development of Botox as a mainstay in the treatment of hyperfunctional facial lines in the upper face. Since its approval by the U.S. Food and Drug Administration for the treatment of facial rhytids (2002), botulinum toxin A has expanded into wide-spread clinical use. Forehead, glabellar, and periocular rhytids are the most frequently treated facial regions. Indications for alternative uses for Botox in facial plastic and reconstructive surgery are expanding. These include a variety of well-established procedures that use Botox as an adjunctive agent to enhance results. In addition, Botox injection is finding increased usefulness as an independent modality for facial rejuvenation and rehabilitation. The agent is used beyond its role in facial rhytids as an effective agent in the management of dynamic disorders of the face and neck. Botox injection allows the physician to precisely manipulate the balance between complex and conflicting muscular interactions, thus resetting their equilibrium state and exerting a clinical effect. This article will address some of the new and unique indications on Botox injection in the face (the lower face and neck, combination with fillers). Important points in terms of its clinical relevance will be stressed, such as an understanding of functional facial anatomy, the importance of precise injections, and correct dosing all are critical to obtaining natural outcomes.