Stability and compatibility of hydromorphone hydrochloride in an implantable infusion system

Long-Term Stability of Hydromorphone in Human Plasma Frozen at −20°C for Three Years Quantified by LC-MS/MS

The long-term stability of drugs under normal laboratory storage conditions (−20°C) for years is important for research purposes, clinical re-evaluation, and also for forensic toxicology. To evaluate the stability of the analgesic opioid hydromorphone, 44 human frozen plasma samples of a former clinical trial were reanalyzed after at least three years. Blood samples were disposed using solid-phase extraction with an additional substitution of stable isotope labelled hydromorphone as an internal standard. Hydromorphone concentrations were determined by ultra-performance liquid chromatography (UPLC) with gradient elution, followed by tandem mass spectrometry with electrospray ionization. Calibration curves demonstrated linearity of the assay in the concentration range of 0.3–20 ng/mL hydromorphone. The limit of detection of the hydromorphone plasma concentration was 0.001 ng/mL, and the lower limit of quantification was 0.3 ng/mL. Intra- and interassay errors did not exceed 16%. The percentage deviation of the measured hydromorphone plasma concentrations between the reanalysis and the first analysis was −1.07% ± 14.8% (mean ± SD). These results demonstrate that hydromorphone concentration in human plasma was stable when the samples were frozen at −20°C over three years. This finding is of value for re-evaluations or delayed analyses for research purposes and in pharmacokinetic studies, such as in forensic medicine.

Stability evaluation of morphine, hydromorphone, metamizole and esketamine containing analgesic mixtures applied for patient‐controlled analgesia in hospice and palliative care

In this study, different injection solutions containing opioid and nonopioid compounds used for patient‐controlled analgesia in hospice and palliative care were evaluated in terms of analyte stability. Investigated injection solutions contained different combinations of morphine, hydromorphone, metamizole and esketamine. For the practical implementation, samples from infusion pumps were daily drawn over a period of 7 days at 22 and 37°C. Quantitative measurements were performed on a high‐performance liquid chromatography system with ultraviolet detection applying a validated analytical method. All compounds apart from morphine showed no evident changes in concentration. However, a significant loss of morphine was observed for injection mixtures containing both morphine and metamizole at 37°C. After 7 days, only 72% of the initially measured morphine concentration was measured in the binary and 77% in the ternary mixture. Furthermore, an additional compound was detected that could represent the morphine‐metamizole‐adduct, “metamorphine”. Based on these results, a significantly reduced morphine concentration must be expected after only 3 days if an injection solution mixture containing both morphine and metamizole is administered to a patient at 37°C. Since the analgesic effects of morphine–metamizole adducts have not yet been thoroughly investigated, further clinical studies are necessary before accurate conclusions can be drawn in this regard.

Stability study of hydromorphone and bupivacaine mixture by HPLC-UV

Objectives

The objective of this study was to evaluate the physical and chemical stability of hydromorphone hydrochloride and bupivacaine hydrochloride in concentrations of 15 mg.ml^-1 and 10 mg.mL^-1 in 0.9% sodium chloride injection. Test samples of hydromorphone/bupivacaine mixtures were stored at 37°C, body temperature encounterd during continuous intrathecal infusion, for 90 days. The solutions were packaged in 20 ml plastic syringes. Evaluations for physical and chemical stability were performed initially and throughout the storage periods. Physical stability was assessed by visual observation. The chemical stability of the drug was evaluated by means of a stability-indicating high-performance liquid chromatographic (HPLC) analytical technique. In addition, pH and osmolarity were measured electronically.

Methods

This study determines the stability and compatibility of hydromorphone (15 mg.ml^-1) and bupivacaine (10 mg.ml^-1) mixture after 3 months at 37°C using a validated method by HPLC-UV. A simple, precise, specific and accurate reversed phase high performance liquid chromatographic (RP-HPLC) method was developed and validated. The different analytical performance parameters such as linearity, accuracy, specificity, precision and sensitivity (limit of detection and limit of quantitation) were determined according to International Conference on Harmonisation ICH Q2 (R1) guidelines. RP-HPLC was conducted on a nucleoshell RP18plus (C18 150×4.6 mm with 2.7 µm particle size) column. The mobile phase consisted of buffer A (phosphate buffer (0.05M) pH 4.5) and acetonitrile B. The gradient used for the elution is the following one: time (min)/% of B: 0 min/20%; 1.9 min/50%; 2.5 min /40%; 4.5 min/40%; 5.5 min/20%; and 8 min /20%, and the flow rate was maintained at 1.0ml.min^-1 and performed at 35°C. The molecules were monitored using Dionex ultimate 3000, equipped with photo diode array detector (λ=210 nm). Linearity was observed in concentration range of 9-21 mg.l^-1 for hydromorphone and 6-14 mg.l^-1 for bupivacaine. All the system suitability parameters were found within the range.

Results

The degradation study shows a photolytic degradation compound for hydromorphone and an oxidative degradation compound found for bupivacaine. The stability study shows no visible haze or particulate formation or gas evolution. pH and osmolarity were stable during the 3 months. Colour changed after 2 months, although this colouring is due to hydromorphone, proportional to hydromorphone concentrations and increases with time but it is a well known modification. The quantitative study by HPLC method revealed no significant change in hydromorphone and bupivacaine concentration. There is less than 5% of variability during the 3-month period.

Conclusions

Hydromorphone (15 mg.ml^-1) and bupivacaine (10 mg.ml^-1) were physically and chemically compatible and analysed with HPLC, which revealed no significant change in hydromorphone and bupivacaine concentration in this simulated compatibility study.

Intrathecal drug delivery system (IDDS) for cancer pain management: a review and updates

Cancer pain remains undertreated and a significant number of patients with cancer pain die from severe untreated pain. With increasing survival rate in cancer, the prevalence of cancer pain is also increasing in number. Though majority of patients with cancer pain can be effectively treated with conventional medical management, still a significant portion of patients required some form of interventional pain management techniques. Among the interventional techniques, intrathecal drug delivery is increasingly used in cancer pain management. Our objective of this article is to review literatures and clinical studies on intrathecal drug delivery system (IDDS) in cancer pain management and to provide updates on its use, precautions, contraindications, side effects and its management, socioeconomic consideration, and management of IDDS in difficult or uncommon situations.

Intrathecal drug therapy for long-term pain management

PURPOSE

The use, safety, and efficacy of intrathecal medication administration with implantable pumps for cancer and chronic pain management are reviewed.

SUMMARY

Implanted intrathecal drug-delivery systems (IDDSs) are used for long-term management of persistent, severe pain despite a multimodal approach with conventional pain treatment options. Currently, consensus papers published in the literature are used as guidelines for determining patient selection and medication administration, because there is a lack of supporting evidence from randomized, controlled, clinical trials. Pharmacists have a critical role in the safe use of intrathecal medication. Most of the medication concentrations and combinations administered through IDDSs are not commercially available and therefore must be compounded in a pharmacy. Medications commonly administered through IDDSs include opioids, local anesthetics, clonidine, baclofen, and ziconotide. It is important for pharmacists who prepare products for IDDSs to understand the pharmacology, adverse effects, and concentration limitations of each medication in order to prevent adverse events related to postoperative subarachnoid hemorrhage, infection, catheter-tip inflammatory masses, withdrawal, and overdose. Pharmacists play an important role in maintaining quality assurance of intrathecal drug use, including the use of standard procedures for ordering and compounding medications, documentation of patient education, and monitoring of patient outcomes.

CONCLUSION

The use of long-term intrathecal drug delivery for the treatment of intractable pain or intolerable medication adverse effects has expanded to include the treatment of patients with chronic or cancer-related pain. Important considerations for the use of intrathecal drug therapy include the appropriate selection of patients, delivery systems, and medications, as well as potential complications of therapy and quality-assurance measures necessary to ensure patient safety.

Development of an implantable intrathecal drug infusion pump

An intrathecal drug infusion system has been designed, manufactured and tested. The system is composed of a drug reservoir and a pump/controller assembly. The drug reservoir made of SUS316L is a negative pressure gas chamber enclosing a bellows type drug chamber. The pump/controller assembly includes a bacterial filter, a controller circuit board, a battery and a micropump, and is connected to a catheter for intrathecal infusion. The micropump implements a peristaltic pumping of the drug by a sequential motion of three pairs of cam and cam-follower. In vitro performance tests were conducted with prototypes.

A Review of Intrathecal Fentanyl and Sufentanil for the Treatment of Chronic Pain

Intrathecal infusion of morphine using implantable pumps is an accepted practice for long-term management of chronic pain. Despite clinical benefit, development of tolerance and side-effects associated with intrathecal morphine has prompted investigators to explore alternative opioids such as the potent anilinopiperidine analogs, fentanyl, and sufentanil. Relevant preclinical and clinical literature from the MEDLINE database was used primarily for this review. In vitro, both compounds are stable in solution, but studies have not been conducted using implantable pumps under simulated use conditions (e.g., long-term stability at body temperature). Preclinical studies of limited duration have demonstrated efficacy, but safety-toxicology studies have been limited to intermittent boluses of sufentanil only. Few clinical reports on the use of intrathecal sufentanil or fentanyl for chronic pain are available. Although results confirm potency and efficacy with intrathecal administration, further studies are needed to support the long-term use of either opioid in chronic pain management.

Stability of clonidine in clonidine-hydromorphone mixture from implanted intrathecal infusion pumps in chronic pain patients

Clonidine is frequently added to opioids in implantable intrathecal pumps for the management of chronic pain. In such devices, a small non-retrievable volume is always present in the reservoir, and its effect on drug stability is unknown. Furthermore, stability of clonidine, when mixed with hydromorphone, has not been previously determined. This study examined the stability of clonidine when co-administered with hydromorphone in implanted intrathecal pumps. Samples of hydromorphone-clonidine before pump refill and from residual solution at subsequent refill were obtained from chronic pain patients. Clonidine concentration was measured using HPLC. Twenty paired samples from 3 patients were analyzed. All 3 patients had a SynchroMed pump implanted for 3-5 years. We found no loss in clonidine concentration during the time between refills (35 +/- 13 days), and no correlation between clonidine concentration and time interval between refills. In conclusion, clonidine, mixed with hydromorphone, is stable when delivered by implantable intrathecal pump for long-term use.

Polyanalgesic Consensus Conference 2003: an update on the management of pain by intraspinal drug delivery-- report of an expert panel

Intraspinal drug infusion using fully implantable pump and catheter systems is a safe and effective therapy for selected patients with chronic pain. The options for this approach are increasing, as drugs that are commercially available for systemic administration are adapted to this use and other drugs that are in development specifically for intraspinal administration become available. In 2000 a Polyanalgesic Consensus Conference was organized to evaluate the existing literature and develop guidelines for drug selection. The major outcome of this effort, an algorithm for drug selection, was based on the best available evidence at the time. Rapid changes have occurred in the science and practice of intraspinal infusion and a Polyanalgesic Consensus Conference 2003 was organized to pursue the following goals: 1) to review the literature on intraspinal drug infusion since 1999, 2) to revise the 2000 drug-selection algorithm, 3) to develop guidelines for optimizing drug dosage and concentration, 4) to create a process for documenting minimum evidence supporting the use of a drug for intraspinal infusion, and 5) to clarify issues pertaining to compounding of drugs. Based on the best available evidence and expert opinion, consensus recommendations were developed in all these areas. The panel's conclusions may provide a foundation for clinical practice and a rational basis for new research.

Stability and compatibility of morphine-clonidine admixtures in an implantable infusion system

Nonopioid analgesics are often coadministered with intrathecal morphine to increase efficacy. The purpose of this study was to evaluate stability and compatibility of morphine-clonidine admixtures with an implantable infusion system that is commonly used to treat pain patients. Infusion systems were filled with admixture and maintained at 37 degrees C for 90 days. Samples were collected monthly. Drug concentrations were determined using stability-indicating, high-performance liquid chromatography. For compatibility testing, individual materials comprising the fluid pathway of the device were immersed in clonidine solution and stored at 37 degrees C for various periods through 64 weeks and mechanical performance evaluated. After 3 months of containment in the infusion system, morphine and clonidine concentrations remained at > or = 94% of the theoretical starting concentrations. All device materials retained acceptable mechanical performance following clonidine exposure. These results demonstrate that morphine and clonidine are stable when combined in aqueous solution maintained at body temperature in an implantable infusion system for at least 3 months.