Importance of analytical methods in pharmacokinetic and drug metabolism studies

Hirtz, J

doi:10.1002/bdd.2510070402

Cited by 14 publications

(8 citation statements)

References 28 publications

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“…Toxicology analysis of pump reservoir medications should not be performed with immunoassay techniques because currently available commercial kits for routine toxicology analysis of biological samples may be associated with falsely positive results. To provide definitive analysis, liquid or gas chromatography, coupled with mass spectroscopy, are more appropriate techniques (13,14).…”

Section: Discussionmentioning

confidence: 99%

Dissociative Mental State in a Patient with an Intrathecal Drug Administration System

Loughrey

Nedeljković

2002

Anesthesia &Amp; Analgesia

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A dvances in technology for long-term intrathecal drug administration, along with evolving knowledge about the neurophysiology and pharmacology of spinal nociception, have created a new option for enhanced analgesia for patients suffering from chronic pain. As noted in a review involving 13,342 mainly US-based chronic pain patients, the use of long-term infusions of intrathecal medications has significantly increased (1). Intrathecal drug administration is cost-effective when compared with other analgesic modalities for patients with failed back surgery syndrome (2). The practice of using drugs other than morphine is also increasing despite little data on long-term safety of such adjuvant therapy.Neuraxial administration of opioids can cause central nervous system (CNS) excitation, which can manifest as delirium or agitation (3). Significant neural toxicity can occur if inappropriate medications are infused intrathecally via an implanted reservoir. In evaluating patients who present with neuropsychiatric disorders and who have a spinal catheter in situ, the supraspinal effects of intrathecal infusions should be considered. We describe a patient who developed an acute dissociative mental state, which resolved on removal of intrathecal medication from his pump reservoir. Toxicology analysis revealed that the injectate was falsely positive for phencyclidine and methadone. Case ReportA 55-yr-old man suffering from chronic back and left leg pain was referred to the pain management center for consideration of a trial of intrathecal opiates. He had undergone numerous interventional pain management techniques at other centers over the previous 10 yr, including a trial of dorsal column stimulation, and was knowledgeable about sophisticated modalities of pain control. His intake of medications included 75-85 mg/d of oxycodone. His medical history was significant for previous lumbar discectomy, depression, and gastric bypass surgery.After psychological evaluation, the patient underwent a trial of intrathecal opioid administration that resulted in significant pain reduction and was subsequently implanted with a Medtronic Synchromed ® (Medtronic, Minneapolis, MN) intrathecal pump. Tolerance to intrathecal morphine developed rapidly, requiring progressive increases in the daily dose from 2 mg/d immediately after implantation to 13.8 mg/d 6 mo later. The infusion comprised of a complexcontinuous pattern involving several dosage adjustments daily. During this time, the patient experienced no apparent mental status changes despite escalating intrathecal opioid doses and continuation of oral opioids.Approximately 7 mo after the initiation of intrathecal therapy, the patient exhibited cognitive deterioration, presenting to the emergency room in a dissociative mental state. This had developed acutely over the previous 3 days and featured stammering speech, mild lethargy, blunting of affect, and both long-and short-term memory loss. There was no history of head trauma, and no definitive injuries were identified. The cognitive deficit...

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Section: Discussionmentioning

confidence: 99%

Dissociative Mental State in a Patient with an Intrathecal Drug Administration System

Loughrey

Nedeljković

2002

Anesthesia &Amp; Analgesia

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“…As a rule, these measurements in biological materials are validated so that accurate and reliable information is generated. Among the various methods that permit drugs and their metabolites to be separated, indentified and quantitatively assayed, chromatography is the most frequently employed (Hirtz 1986), in particular liquid chromatography (LC) coupled to different detectors such as mass spectrometer (MS) or UV detector. Indeed, the LC-MS methods are considered as most appropriate for determination of drugs and their metabolites and are also best suited for high throughput analysis (Roškar and Lušin 2012).…”

Section: Measurement Of Drug Concentrationsmentioning

confidence: 99%

High-amylose carboxymethyl starch matrices for oral sustained drug-release: In vitro and in vivo evaluation

Nabais

Brouillet

Kyriacos

et al. 2007

European Journal of Pharmaceutics and Biopharmaceutics

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“…They are relatively expensive because of the cost of reagent kits but are less time-consuming and technically less demanding than the chromatographic techniques. A complete coverage of the analytical techniques used in pharmacokinetic research is beyond the scope of this review but several papers that deal with this area have recently been published (8)(9)(10)(11)(12)(13).…”

Section: Analytical M E T H O D Smentioning

confidence: 99%

Preanalytical Considerations in Drug Assays in Clinical Pharmacokinetic Studies

Mehta¹

1989

J Clin Pharm Ther

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SUMMARYMany hospital pharmacy laboratories undertake drug analysis in biological fluids for the production of pharmacokinetic data. The success of such an undertaking very much depends on the selection of a suitable analytical method and a proper approach to sample collection and handling. This paper surveys the main types of biological specimens taken from the patients for pharmacokinetic drug analysis and discusses factors that affect them during or subsequent to their removal. Guidelines are provided in specimen handling and dealing with many problems which could arise prior to actual analysis. By its very nature this paper brings in many disciplines, the full details of which are well beyond its scope, however, some discussion on pharmacokinetic and bioavailability methods in relation to sampling procedures is included to put the matter into a proper perspective. I N T R O D U C T I O NIn addition to the choice of a suitable analytical technique, analysis of drugs and metabolites in biological fluids for pharmacokinetic and bioavailability studies require detailed consideration of such factors as the methods for collection, handling, and preparation of samples before analysis, and stability of samples under various storage conditions. The preanalytical phase of drug analysis, though very important, does not always receive sufficient attention which is surprising because improper sampling and storage can alter the sample and consequently incorrect results can be obtained. Availability of sophisticated equipment has little meaning if the sample integrity prior to analysis is not maintained. This review attempts to remedy this situation and offers some general guidelines on ways of preparing samples for drug bioanalysis. Preanalytical treatment of those body fluids which are commonly used in clinical pharmacokinetic work, i.e. blood (plasma or serum), urine, saliva and cerebrospinal fluid (CSF), will be considered here. ANALYTICAL M E T H O D SPharmacokinetic studies in man involve quantifying of drug and/or metabolite levels in appropriate body fluids or tissues at any point in time following drug administration 285

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Importance of analytical methods in pharmacokinetic and drug metabolism studies

Cited by 14 publications

References 28 publications

Dissociative Mental State in a Patient with an Intrathecal Drug Administration System

Dissociative Mental State in a Patient with an Intrathecal Drug Administration System

High-amylose carboxymethyl starch matrices for oral sustained drug-release: In vitro and in vivo evaluation

Preanalytical Considerations in Drug Assays in Clinical Pharmacokinetic Studies

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