Comparison of pharmacokinetics software for therapeutic drug monitoring of piperacillin in patients with severe infections

OBJECTIVE

To evaluate the predictive performance of population pharmacokinetic models for piperacillin (PIP) available in the software MwPharm, TDMx and ID-ODs for initial dosing selection and therapeutic drug monitoring (TDM) purposes.

METHODS

This is a prospective observational study in adult patients with severe infections receiving PIP treatment. Plasma concentrations were quantified by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. The differences between predicted and observed PIP concentrations were evaluated with Bland-Altman plots; additionally, the relative and absolute bias and precision of the models were determined.

RESULTS

A total of 145 PIP plasma concentrations from 42 patients were analysed. For population prediction, MwPharm showed the best predictive performance with a mean relative difference of 34.68% (95% CI -197% to 266%) and a root mean square error (RMSE) of 60.42 µg/mL; meanwhile TDMx and ID-ODs under-predicted PIP concentrations. For individual prediction, the TDMx model was found to be the most precise with a mean relative difference of 7.61% (95% CI -57.63 to 72.86%), and RMSE of 17.86 µg/mL.

CONCLUSION

Current software for TDM is a valuable tool, but it may also include different population pharmacokinetic models in patients with severe infections, and should be evaluated before performing a model-based TDM in clinical practice. Considering the heterogeneous characteristics of patients with severe infections, this study demonstrates the need for therapy personalisation for PIP to improve pharmacokinetic/pharmacodynamic target attainment.

Effect of Clindamycin on Intestinal Microbiome and Miltefosine Pharmacology in Hamsters Infected with Leishmania infantum

Visceral leishmaniasis (VL), a vector-borne parasitic disease caused by Leishmania donovani and L. infantum (Kinetoplastida), affects humans and dogs, being fatal unless treated. Miltefosine (MIL) is the only oral medication for VL and is considered a first choice drug when resistance to antimonials is present. Comorbidity and comedication are common in many affected patients but the relationship between microbiome composition, drugs administered and their pharmacology is still unknown. To explore the effect of clindamycin on the intestinal microbiome and the availability and distribution of MIL in target organs, Syrian hamsters (120-140 g) were inoculated with L. infantum (108 promastigotes/animal). Infection was maintained for 16 weeks, and the animals were treated with MIL (7 days, 5 mg/kg/day), clindamycin (1 mg/kg, single dose) + MIL (7 days, 5 mg/kg/day) or kept untreated. Infection was monitored by ELISA and fecal samples (16 wpi, 18 wpi, end point) were analyzed to determine the 16S metagenomic composition (OTUs) of the microbiome. MIL levels were determined by LC-MS/MS in plasma (24 h after the last treatment; end point) and target organs (spleen, liver) (end point). MIL did not significantly affect the composition of intestinal microbiome, but clindamycin provoked a transient albeit significant modification of the relative abundance of 45% of the genera, including Ruminococcaceae UCG-014, Ruminococcus 2; Bacteroides and (Eubacterium) ruminantium group, besides its effect on less abundant phyla and families. Intestinal dysbiosis in the antibiotic-treated animals was associated with significantly lower levels of MIL in plasma, though not in target organs at the end of the experiment. No clear relationship between microbiome composition (OTUs) and pharmacological parameters was found.

Antiparkinsonian Agents in Investigational Polymeric Micro- and Nano-Systems

Parkinson's disease (PD) is a devastating neurodegenerative disease characterized by progressive destruction of dopaminergic tissue in the central nervous system (CNS). To date, there is no cure for the disease, with current pharmacological treatments aimed at controlling the symptoms. Therefore, there is an unmet need for new treatments for PD. In addition to new therapeutic options, there exists the need for improved efficiency of the existing ones, as many agents have difficulties in crossing the blood-brain barrier (BBB) to achieve therapeutic levels in the CNS or exhibit inappropriate pharmacokinetic profiles, thereby limiting their clinical benefits. To overcome these limitations, an interesting approach is the use of drug delivery systems, such as polymeric microparticles (MPs) and nanoparticles (NPs) that allow for the controlled release of the active ingredients targeting to the desired site of action, increasing the bioavailability and efficacy of treatments, as well as reducing the number of administrations and adverse effects. Here we review the polymeric micro- and nano-systems under investigation as potential new therapies for PD.

Leishmania infantum infection does not affect the main composition of the intestinal microbiome of the Syrian hamster

BACKGROUND

Visceral leishmaniasis (VL) is the most severe form of all leishmanial infections and is caused by infection with protozoa of Leishmania donovani and Leishmania infantum. This parasitic disease occurs in over 80 countries and its geographic distribution is on the rise. Although the interaction between the intestinal microbiome and the immune response has been established in several pathologies, it has not been widely studied in leishmaniasis. The Syrian hamster is the most advanced laboratory model for developing vaccines and new drugs against VL. In the study reported here, we explored the relationship between the intestinal microbiome and infection with L. infantum in this surrogate host.

METHODS

Male Syrian hamsters (120-140 g) were inoculated with 108 promastigotes of a canine-derived L. infantum strain or left as uninfected control animals. Infection was maintained for 19 weeks (endpoint) and monitored by an immunoglobulin G (IgG) enyzme-linked immunosorbent assay throughout the experiment. Individual faecal samples, obtained at weeks 16, 18 and 19 post-inoculation, were analysed to determine the 16S metagenomic composition (the operational taxonomic units [OTUs] of the intestinal microbiome and the comparison between groups were FDR (false discovery rate)-adjusted).

RESULTS

Leishmania infantum infection elicited moderate clinical signs and lesions and a steady increase in specific anti-Leishmania serum IgG. The predominant phyla (Firmicutes + Bacteriodetes: > 90%), families (Muribaculaceae + Lachnospiraceae + Ruminococcaceae: 70-80%) and genera found in the uninfected hamsters showed no significant variations throughout the experiment. Leishmania infantum infection provoked a slightly higher-albeit non-significant-value for the Firmicutes/Bacteriodetes ratio but no notable differences were found in the relative abundance or diversity of phyla and families. The microbiome of the infected hamsters was enriched in CAG-352, whereas Lachnospiraceae UCG-004, the [Eubacterium] ventriosum group and Allobaculum were less abundant.

CONCLUSIONS

The lack of extensive significant differences between hamsters infected and uninfected with L. infantum in the higher taxa (phyla, families) and the scarce variation found, which was restricted to genera with a low relative abundance, suggest that there is no clear VL infection-intestinal microbiome axis in hamsters. Further studies are needed (chronic infections, co-abundance analyses, intestinal sampling, functional analysis) to confirm these findings and to determine more precisely the possible relationship between microbiome composition and VL infection.

Functionalization of Morin-Loaded PLGA Nanoparticles with Phenylalanine Dipeptide Targeting the Brain

Alzheimer’s disease (AD) is the most prevalent neurodegenerative disorder, with its incidence constantly increasing. To date, there is no cure for the disease, with a need for new and effective treatments. Morin hydrate (MH) is a naturally occurring flavonoid of the Moraceae family with antioxidant and anti-inflammatory properties; however, the blood–brain barrier (BBB) prevents this flavonoid from reaching the CNS when aiming to potentially treat AD. Seeking to use the LAT-1 transporter present in the BBB, a nanoparticle (NPs) formulation loaded with MH and functionalized with phenylalanine-phenylalanine dipeptide was developed (NPphe-MH) and compared to non-functionalized NPs (NP-MH). In addition, two formulations were prepared using rhodamine B (Rh-B) as a fluorescent dye (NPphe-Rh and NP-Rh) to study their biodistribution and ability to cross the BBB. Functionalization of PLGA NPs resulted in high encapsulation efficiencies for both MH and Rh-B. Studies conducted in Wistar rats showed that the presence of phenylalanine dipeptide in the NPs modified their biodistribution profiles, making them more attractive for both liver and lungs, whereas non-functionalized NPs were predominantly distributed to the spleen. Formulation NPphe-Rh remained in the brain for at least 2 h after administration.

Amikacin pharmacokinetics in elderly patients with severe infections

OBJECTIVE

The aim of this study was to characterize the population pharmacokinetics of amikacin in elderly patients by means of nonlinear mixed effects modelling and to propose initial dosing schemes to optimize therapy based on PK/PD targets.

METHOD

A total of 137 elderly patients from 65 to 94 years receiving intravenous amikacin and routine therapeutic drug monitoring at Hospital Universitario Severo Ochoa were included. Concentration-time data and clinical information were retrospectively collected; initial doses of amikacin ranged from 5.7 to 22.5 mg/kg/day and each patient provided between 1 and 10 samples.

RESULTS

Amikacin pharmacokinetics were best described by a two-compartment open model; creatinine clearance (CrCL) was related to drug clearance (2.75 L/h/80 mL/min) and it was augmented 28% when non-steroidal anti-inflammatory drugs were concomitantly administered. Body mass index (BMI) influenced the central volume of distribution (17.4 L/25 kg/m²). Relative absolute prediction error was reduced from 33.2% (base model) to 17.9% (final model) when predictive performance was evaluated with a different group of elderly patients. A nomogram for initial amikacin dosage was developed and evaluated based on stochastic simulations considering final model to achieve PK/PD targets (Cmax/MIC>10 and AUC/MIC>75) and to avoid toxic threshold (Cmin<2.5 mg/L).

CONCLUSION

Initial dosing approach for amikacin was designed for elderly patients based on nonlinear mixed effects modeling to maximize the probability to attain efficacy and safety targets considering individual BMI and CrCL.

Micro- and Nano-Systems Developed for Tolcapone in Parkinson’s Disease

To date there is no cure for Parkinson’s disease (PD), a devastating neurodegenerative disorder with levodopa being the cornerstone of its treatment. In early PD, levodopa provides a smooth clinical response, but after long-term therapy many patients develop motor complications. Tolcapone (TC) is an effective adjunct in the treatment of PD but has a short elimination half-life. In our work, two new controlled delivery systems of TC consisting of biodegradable PLGA 502 (poly (D,L-lactide-co-glycolide acid) microparticles (MPs) and nanoparticles (NPs) were developed and characterized. Formulations MP-TC4 and NP-TC3 were selected for animal testing. Formulation MP-TC4, prepared with 120 mg TC and 400 mg PLGA 502, exhibited a mean encapsulation efficiency (EE) of 85.13%, and zero-order in vitro release of TC for 30 days, with around 95% of the drug released at this time. Formulation NP-TC3, prepared with 10 mg of TC and 50 mg of PLGA 502, exhibited mean EE of 56.69%, particle size of 182 nm, and controlled the release of TC for 8 days. Daily i.p. (intraperitoneal) doses of rotenone (RT, 2 mg/kg) were given to Wistar rats to induce neurodegeneration. Once established, animals received TC in saline (3 mg/kg/day) or encapsulated within formulations MP-TC4 (amount of MPs equivalent to 3 mg/kg/day TC every 14 days) and NP-TC3 (amount of NPs equivalent to 3 mg/kg/day TC every 3 days). Brain analyses of Nissl-staining, GFAP (glial fibrillary acidic protein), and TH (tyrosine hydroxylase) immunohistochemistry as well as behavioral testing (catalepsy, akinesia, swim test) showed that the best formulation was NP-TC3, which was able to revert PD-like symptoms of neurodegeneration in the animal model assayed.

Development and Validation of an HPLC Method for the Quantification of Morin Flavonoid Encapsulated within PLGA Nanoparticles

Background:

Morin flavonoid exerts neuroprotective effects with potential interest in neurodegenerative disorders. For this, the use of surface-modified polymeric nanoparticles loaded with morin is an interesting approach.

Objective:

To develop and validate an HPLC method for the quantification of morin released from a new delivery system consisting of poly lactic-co-glycolic (PLGA) nanoparticles functionalized with the dipeptide phe-phe (phenylalanine-phenylalanine) used to facilitate their access to the CNS.

Method:

The HPLC procedure was developed and validated with morin hydrate dissolved either in methanol (method A) or in methanol: 0.1N HCl (50:50, v/v, method B). Two new nanoparticle formulations were developed and characterized: morin-loaded PLGA nanoparticles (formulation F1), and morin-loaded PLGA phe-phe nanoparticles (formulation F2).

Results:

Method A was linear within the concentration range of 5-30 μg.mL-1 and, 1-30 μg mL-1 for method B. LOD and LOQ with method A were 1.23 μg.mL-1 and 3.90 μg.mL-1, respectively, and 0.481 μg.mL-1 and 1.458 μg.mL-1, respectively for method B. The average amount of phe-phe bound to formulation F2 (50 mg of NPs) was 431.33 μg. The encapsulation efficiency of morin within PLGA nanoparticles was around 80%. After functionalization, this value decreased significantly.

Conclusion:

Method B showed better sensitivity, accuracy and precision for the quantification of morin. The procedure used to functionalize the nanoparticles was adequate for linking the dipeptide to their surfaces, but this procedure is not adequate when encapsulating water-soluble compounds.

Potential Active Targeting of Gatifloxacin to Macrophages by Means of Surface-Modified PLGA Microparticles Destined to Treat Tuberculosis

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis and represents one of the leading causes of mortality worldwide due to multidrug-resistant TB (MDR-TB). In our work, a new formulation of biodegradable PLGA microparticles was developed for pulmonary administration of gatifloxacin, using a surface modifier agent to actively target alveolar macrophages thereby allowing to gain access of the drug to Mycobacterium tuberculosis. For this, rapid uptake of the particles by macrophages is beneficial. This process was evaluated with fluorescein-loaded microparticles using PLGA 502 or PLGA 502H as polymers and labrafil as surface modifier. Cell phagocytosis was studied in raw 264.7 mouse macrophage cell line after 3, 5, 24, and 48 h incubation with the microparticles. Labrafil enhanced the uptake rate of PLGA 502H microparticles by macrophages which was directly related to the modification of the polymer matrix. Gatifloxacin-loaded PLGA microparticles using PLGA 502 or PLGA 502H and labrafil were prepared. From our results, only microparticles prepared with PLGA 502H and labrafil exhibited high encapsulation efficiency (89.6 ± 0.2%), rapid phagocytosis by macrophages (3 h), and remained inside the cells for at least 48 h, thereby resulting in a suitable carrier to potentially treat MDR-TB.

Efficacy of Ropinirole-Loaded PLGA Microspheres for the Reversion of Rotenone- Induced Parkinsonism

A new controlled delivery system has been developed for ropinirole (RP) for the treatment of Parkinson´s Disease (PD) consisting in PLGA microparticles (MPs) which exhibited in vitro constant release of RP (78.23 µg/day/10 mg MPs) for 19 days. The neuroprotective effects of RP released from MPs were evaluated in SKN-AS cells after exposure to rotenone (20 µM). Cell apoptosis was significantly reduced by RP (100-120 µM). Daily doses of rotenone (2 mg/kg) given i.p. to rats induced neuronal and behavioral changes similar to those of PD. After 15 days, animals received RP in saline (1 mg/kg/day for 45 days) or as MPs at two dose levels (amount of MPs equivalent to 7.5 mg/kg or 15 mg/kg RP given on days 15 and 30). Brain immunochemistry (Nisslstaining, GFAP and TH immunohistochemistry) and behavioral testing (catalepsy, akinesia, rotarod and swim test) showed that animals receiving RP either in solution or encapsulated within the MPs reverted the PD symptoms with the best results obtained in animals receiving RP microspheres at the highest dose assayed, thereby confirming the potential therapeutic interest of the new RP delivery system.

Nanotechnology-based drug delivery of ropinirole for Parkinson's disease

A new drug delivery system is developed for ropinirole (RP) for the treatment of Parkinson’s disease (PD) consisting of biodegradable poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs). The formulation selected was prepared with 8 mg RP and 50 mg PLGA 502. This formulation exhibited mean encapsulation efficiency of 74.8 ± 8.2%, mean particle size lower than 155 nm, the zeta potential of −14.25 ± 0.43 mV and zero-order in vitro release of RP (14.13 ± 0.17 μg/h/10 mg NPs) for 5 d. Daily doses of the neurotoxin rotenone (2 mg/kg) given i.p. to male Wistar rats induced neuronal and behavioral changes similar to those of PD. Once neurodegeneration was established (15 d) animals received RP in saline (1 mg/kg/d for 35 d) or encapsulated within PLGA NPs (amount of NPs equivalent to 1 mg/kg/d RP every 3 d for 35 d). Brain histology and immunochemistry (Nissl-staining, glial fibrillary acidic protein and tyrosine hydroxylase immunohistochemistry) and behavioral testing (catalepsy, akinesia, rotarod and swim test) showed that RP-loaded PLGA NPs were able to revert PD-like symptoms of neurodegeneration in the animal model assayed.

Surface-modified gatifloxacin nanoparticles with potential for treating central nervous system tuberculosis

A new nanocarrier is developed for the passage of gatifloxacin through the blood-brain barrier to treat central nervous system tuberculosis. Gatifloxacin nanoparticles were prepared by nanoprecipitation using poly(lactic-co-glycolic acid) (PLGA) 502 and polysorbate 80 or Labrafil as surface modifiers. The evaluation of in vivo blood-brain barrier transport was carried out in male Wistar rats using rhodamine-loaded PLGA nanoparticles prepared with and without the surface modifiers. At 30 and 60 minutes after administration, nanoparticle biodistribution into the brain (hippocampus and cortex), lungs, and liver was studied. The results obtained from the cerebral cortex and hippocampus showed that functionalization of rhodamine nanoparticles significantly increased their passage into the central nervous system. At 60 minutes, rhodamine concentrations decreased in both the lungs and the liver but were still high in the cerebral cortex. To distinguish the effect between the surfactants, gatifloxacin-loaded PLGA nanoparticles were prepared. The best results corresponded to the formulation prepared with polysorbate 80 with regard to encapsulation efficiency (28.2%), particle size (176.5 nm), and ζ-potential (-20.1 mV), thereby resulting in a promising drug delivery system to treat cerebral tuberculosis.

Controlled release of rasagiline mesylate promotes neuroprotection in a rotenone-induced advanced model of Parkinson's disease

Microencapsulation of rasagiline mesylate (RM) into PLGA microspheres was performed by method A (O/W emulsion) and method B (W/O/W double emulsion). The best formulation regarding process yield, encapsulation efficiency and in vitro drug release was that prepared with method A, which exhibited constant drug release for two weeks (K(0)=62.3 μg/day/20mg microspheres). Exposure of SKN-AS cells to peroxide-induced oxidative stress (1 mM) resulted in cell apoptosis which was significantly reduced by RM (40.7-102.5 μM) as determined by cell viability, ROS production and DNA fragmentation. Daily doses of rotenone (2 mg/kg) given i.p. to rats for 45 days induced neuronal and behavioral changes similar to those occurring in PD. Once an advanced stage of PD was achieved, animals received RM in saline (1 mg/kg/day) or encapsulated within PLGA microspheres (amount of microspheres equivalent to 15 mg/kg RM given on days 15 and 30). After 45 days RM showed a robust effect on all analytical outcomes evaluated with non-statistically significant differences found between its administration in solution or within microparticles however; with this controlled release system administration of RM could be performed every two weeks thereby making this new therapeutic system an interesting approach for the treatment of PD.

An effective novel delivery strategy of rasagiline for Parkinson's disease

This is the first report on the efficacy of a new controlled release system developed for rasagiline mesylate (RM) in a rotenone-induced rat model of Parkinson's disease (PD). PLGA microspheres in vitro released RM at a constant rate of 62.3 μg/day for two weeks. Intraperitoneal injection of rotenone (2 mg/kg/day) to Wistar rats produced typical PD symptoms. Catalepsy, akinesia and swim tests outcomes in animals receiving RM either in solution or within microspheres showed a reversal in descent latency when compared to rotenone-treated animals, being this reversal specially pronounced in animals receiving RM microspheres (dose equivalent to 1 mg/kg/day RM injected i.p. every 15 days). Nissl-staining of brain sections showed selective degeneration of the substantia nigra (SNc) dopaminergic neurons in rotenone-treated animals which was markedly reverted by RM microspheres. PET/CT with (18)F-DG resulted in mean increases of accumulation of radiotracer in striatum and SNc of around 40% in animals treated with RM microspheres which also had significant beneficial effects on Bcl-2, Bax, TNF-α mRNA and SOD2 levels as detected by real-time RT-PCR. Our results confirm the robust effect achieved by the new controlled release system developed for RM which exhibited better in vivo efficacy than RM given in solution.

Compatibility and stability of ternary admixtures of tramadol, haloperidol, and hyoscine N-butyl bromide: retrospective clinical evaluation

BACKGROUND

Combination of drugs for subcutaneous infusion is common practice in palliative medicine, however, there is no information pertaining to the compatibility and stability of tramadol combined in ternary admixtures and no information exists regarding its clinical performance.

METHODS

Tramadol hydrochloride, haloperidol lactate, and hyoscine N-butyl bromide have been examined for compatibility and stability when combined in solution under conditions mimicking their potential use via subcutaneous infusion in terminal oncology patients. Concentration ranges were 8.8-33.3 mg/mL, 0.208-0.624 mg/mL, and 3.33-6.67 mg/mL for tramadol hydrochloride, haloperidol lactate, and hyoscine N-butyl bromide. With these, 27 different admixtures were prepared and stored at 25 degrees C using 0.9% saline as diluent. Quantification was performed by high-performance liquid chromatography (HPLC). The clinical performance of the admixture was retrospectively assessed in 28 terminal oncology patients exhibiting Karnofsky's indexes of 10%-20%.

RESULTS

All three drugs were very stable (>92%) at 25 degrees C for 15 days. Pain was completely controlled in all patients. Fifty percent of the patients suffered from 3-5 vomiting episodes per day and of these, 75% experienced complete control of the episodes. None of the patients showed local reactions after subcutaneous administration of the admixture.

RESULTS

Our results confirm the compatibility and stability of the ternary admixture and its utility in highly vulnerable patients exhibiting moderate symptoms.

Downregulation of endotoxin-induced uveitis by intravitreal injection of polylactic-glycolic acid (PLGA) microspheres loaded with dexamethasone

We tested the short- and long-term ability of polylactic-glycolic acid (PLGA) microspheres loaded with dexamethasone to reduce ocular inflammation in rabbits elicited by intravitreal lipopolysaccharide (LPS) injection. PLGA microspheres loaded with dexamethasone were prepared by the solvent evaporation technique from an oil/water emulsion and sterilized by gamma irradiation (25 kGy). The microsphere fraction selected was 2:10 (dexamethasone:PLGA) and contained 141 +/- 0.38 microg dexamethasone/mg PLGA. Microsphere diameters were 20-53 microm, and the mean encapsulation efficiency was 92.97 +/- 0.75%. Seven days prior to the induction of panuveitis, 10 mg of dexamethasone-free or dexamethasone-loaded microspheres were injected into the vitreous. Control animals received no injection. Panuveitis was induced in male New Zealand rabbits (2.5-3.0 kg) by intravitreal injection of Escherichia coli LPS. Clinical evaluation, electroretinography and histopathologic studies were performed in short-term studies of 15 days and in long-term studies of 33 days. Efficacy in reducing inflammation was also studied in vitrectomized eyes. In short-term studies eyes injected with dexamethasone-loaded microspheres had less inflammation than control eyes and eyes injected with blank microspheres. Inflammation reverted in all groups by 15 days after LPS injection. A second LPS dose given on Day 30 provoked a high peak of inflammation in control eyes and in those injected with blank microspheres. In contrast, only slight inflammation occurred in eyes injected with dexamethasone-loaded microspheres. Histopathology and electroretinography supported these results. Dexamethasone-loaded microspheres effectively reduced intraocular inflammation caused by LPS in both short- and long-term studies.

PEG-derivative effectively modifies the characteristics of indomethacin-PLGA microspheres destined to intra-articular administration

The aim of this study was to obtain biodegradable indomethacin microspheres for intra-articular administration in rheumatoid arthritis, where angiogenic processes are involved. Indomethacin concentrations to achieve an anti-angiogenic effect would be five-times higher than an anti-inflammatory. Microspheres were prepared by solvent evaporation using PLGA. Indomethacin is a poor water-soluble drug with it being possible that dissolved and non-dissolved drug co-exist within the polymeric matrix resulting in rapid release. To control this release, an oil-PEG-derivative was incorporated, producing changes in morphology, crystallinity and indomethacin release. To minimize the amount of microspheres administered, a two-factor five-level central rotable composite 2(2)+star design was employed with two independent variables: indomethacin percentage and PEG-derivative percentage. The optimum formulation showed mean encapsulation efficiency of 94.3+/-2.2% and released 7.99+/-0.25 microg indomethacin/day/mg microspheres for 21 days. A dose of 20-50 mg of this formulation could be appropriate to achieve both anti-angiogenic and anti-inflammatory effects. Preliminary cytotoxicity studies performed in rat splenocytes showed an adequate cell viability.

Compatibility and stability of tramadol and dexamethasone in solution and its use in terminally ill patients

BACKGROUND

Delivery of drug admixtures by continuous subcutaneous infusion is common practice in palliative medicine, but analytical confirmation of their compatibility and stability is not always available.

OBJECTIVE

To study the compatibility and stability of tramadol hydrochloride and dexamethasone sodium phosphate combined in solution and to report on its use in terminally ill patients.

METHOD

Twelve different solutions containing tramadol hydrochloride (8.33-33.33 mg/mL) and dexamethasone sodium phosphate (0.33-3.33 mg/mL) were prepared in saline and stored in polypropylene syringes for 5 days (25 degrees C). Analysis was performed on days 1, 3 and 5 days with simultaneous determination by HPLC. pH was measured at 0 and 5 days. Clinical performance was assessed retrospectively in six terminal-ill oncology patients.

RESULTS

Maximum losses of 7% and 6% were observed for tramadol and dexamethasone. Pain was completely controlled in four patients. Local tolerance resulted in haematoma in three patients, which resolved by switching to a butterfly insertion site.

CONCLUSION

Tramadol hydrochloride (100-400 mg/day) and dexamethasone sodium phosphate (4-40 mg/day) are stable for at least 5 days when combined in saline and stored at 25 degrees C. These results are only valid for the type of syringes and the specific commercial preparations tested.

Compatibiliity and stability of furosemide and dexamethasone combined in infusion solutions

AIM

The goal of palliative care is the achievement of the best quality of life for patients and their families. For this, the administration of drugs by subcutaneous infusion is frequently used since many patients have great difficulties in taking drugs orally and regular intramuscular injections are painful. Usually, drugs are combined in infusion solutions. The objective was therefore to study the compatibility and stability of dexamethasone sodium phosphate (CAS 2392-39-4) and sodium furosemide (CAS 54-31-9) combined in solutions destined to subcutaneous administration in palliative medicine.

METHODS

Twelve different solutions were assessed during 15 days. Drug admixtures were prepared in polypropylene syringes using 0.9 % saline as diluent and stored at 4 degrees C and 25 degrees C in the dark. Initial concentrations were 3.33-10.0 mg/ ml for sodium furosemide (dose range 40-120 mg/day) and 0.33-3.33 mg/ml (dose range 4-40 mg/day) for dexamethasone sodium phosphate. Quantification of both drugs was performed by high-performance liquid chromatography.

RESULTS

After 5 days of storage at both temperatures, the maximum losses obtained were lower than 10 % for both drugs. However, after 15 days, slight precipitation/turbidity was observed in all mixtures. At this time, maximum losses of 20 % were obtained for both drugs.

CONCLUSION

These results confirm the stability of mixtures prepared with sodium furosemide (< or = 120 mg/day) and dexamethasone sodium phosphate (< or = 40 mg/day) for a period of 5 days and with independence of their storage at 4 degrees C or 25 degrees C.

Tramadol and hyoscine N-butyl bromide combined in infusion solutions: compatibility and stability

BACKGROUND

More than two-thirds of patients with metastatic cancer experience pain. Tramadol is one of the most interesting and useful weak opioids used by palliative care units to treat moderate to moderately severe pain. Relief of distressful symptoms in terminally ill patients is of prime importance; a common practice is to administer opioid analgesics in conjunction with other drugs as hyoscine N-butyl bromide, which is very useful in reducing secretions in patients with inoperable malignant bowel obstruction. The pursuit for excellence in symptom control in patients unable to take oral medication has led to the administration of medications by other routes such as the subcutaneous route.

PURPOSE

The purpose of this study was to fulfill the lack of information regarding the compatibility and physical stability of tramadol hydrochloride and hyoscine N-butyl bromide combined in infusion solutions.

METHODS

The stability of nine admixtures (stored in polypropylene syringes) at 4 and 25 degrees C was assessed over a period of 15 days.

RESULTS

Nonstatistically significant losses of tramadol HCl and a maximum loss of 7% for hyoscine N-butyl bromide were obtained. Therefore, tramadol HCl (dose range, 100-400 mg/day) can be formulated together in saline with hyoscine N-butyl bromide (dose range 40-80 mg/day) for s.c. infusion using a 60-ml drug infuser for a duration of 7 days.

Population pharmacokinetics of gentamicin in premature newborns

OBJECTIVES

To determine the pharmacokinetic parameters of gentamicin in a population of 200 premature newborns and to investigate the influence of several clinical and physiopathological covariates on the pharmacokinetics of the drug. To validate the pharmacokinetic analysis performed in another population of 50 premature newborns.

METHODS

A total of 200 premature newborns were evaluated at the neonatal intensive care unit of Severo Ochoa Hospital (Madrid, Spain). Four hundred and seventeen serum drug concentrations were included. Mean gestational age (GA) was 32.19+/-2.97 weeks, mean postnatal age (PNA) was 5.49+/-5.41 days and mean body weight (BW) was 1.68+/-0.63 kg. Fifty additional newborns were studied for validation (mean GA 32.62+/-3.07 weeks, mean PNA 5.17+/-3.77 days and mean BW 1.80+/-0.67 kg). Dosing, serum gentamicin concentrations and 15 covariates were collected. Data analysis was performed with NONMEM. One- and two-compartment open models were evaluated. Four parameters were analysed with the two-compartment open model: clearance (CL), central volume (Vc), peripheral volume (Vp) and intercompartmental clearance (Q).

RESULTS AND CONCLUSIONS

The two-compartment open model was found to significantly better describe gentamicin pharmacokinetics in the neonate. More than PNA or GA, creatinine clearance (CLCR) plays an important role in the elimination of gentamicin in premature newborns. Creatinine clearance is also related to GA. The appropriate dosing regimens given in accordance with the characteristics of the patients are 5 mg/kg/48 h and 4 mg/kg/24 or 36 h for neonates<32 weeks and >or=32 weeks of GA, respectively.

Morphine, haloperidol and hyoscine N-butyl bromide combined in s.c. infusion solutions: Compatibility and stability

The administration of drugs by subcutaneous infusion is routinely practiced in palliative medicine for the management of patients who are no longer able to take oral medication. It is common for two or more drugs to be combined in subcutaneous solutions. The combination of an opioid with other drugs (haloperiol lactate and hyoscine N-butyl bromide) can be very valuable. Unfortunately, the compatibility and stability of morphine hydrochloride, haloperidol lactate and hyoscine N-butyl bromide combined in the same solution has not yet been determined. Therefore, this study examined the stability of ternary solutions containing morphine HCl, haloperidol lactate and hyoscine N-butyl bromide at different dose ranges. Twelve different solutions were assessed for 15 days after preparation in polypropylene syringes using 0.9% saline as diluent. Triplicate syringes were stored at 25 degrees C. HPLC was the analytical technique used to measure morphine HCl, haloperidol lactate and hyoscine N-butyl bromide. Initial concentration ranges were 1.67-10.0 mg/ml for morphine HCl, 0.417-0.625 mg/ml for haloperidol lactate and, 5.0-6.67 mg/ml for hyoscine N-butyl bromide. All three drugs were very stable (>92.5%) when stored at 25 degrees C. The clinical performance of the admixture was retrospectively assessed in 21 terminal oncology patients. Total symptom control was achieved in 17 out of 21 patients with very good local tolerance.

Stability of tramadol and haloperidol for continuous subcutaneous infusion at home

Terminally ill cancer patients commonly suffer from several symptoms at the same time, such as pain, nausea, anxiety, cognitive failure, bowel obstruction, and fatigue. To obtain optimal symptom control, the simultaneous administration of more than one drug by continuous subcutaneous (SC) infusion is often required. Tramadol is considered an effective step II agent of the World Health Organization's analgesic ladder for the control of chronic pain conditions, including neuropathic pain, and also exhibits a good safety profile. Haloperidol has been found to be very efficient in controlling agitation with or without pain, nausea and/or vomiting of central origin, intestinal obstruction, and delirium. Although the combination of tramadol and haloperidol in the same solution for SC infusion may be desirable, the physicochemical stability of this combination has not yet been documented. Therefore, our aim was to study the physicochemical stability of drug admixtures composed of tramadol hydrochloride and haloperidol lactate, which have been stored in polypropylene syringes at 4 degrees C and 25 degrees C, and assayed at 0, 5, 7, and 15 days after preparation.

Interactions of anti-infectives: a review

Drug interactions can be beneficial and valuable, but their consequences are usually adverse/undesirable, thus compromising the efficacy of drugs and enhancing their toxicity. Interactions can be divided into pharmaceutical incompatibilities, and pharmacokinetic and pharmacodynamic interactions. Unexpected drug responses can result from drug-excipient incompatibilities or erroneous technological processes. Pharmacokinetic interactions can affect the processes of drug absorption, distribution, metabolization and excretion. Pharmacodynamic interactions occur when the effects of one drug are changed by the presence of another drug at its site of action; such interactions are classified as synergistic and antagonistic. The clinically most relevant drug interactions following this classification and regarding the use of anti-infectives are reviewed. Knowledge, research and discussion of drug interactions will assist in giving the patient optimal care.

Stability and compatibility of binary mixtures of morphine hydrochloride with hyoscine-n-butyl bromide

The aim of this study was to determine the compatibility and stability of morphine hydrochloride and hyoscine-N-butyl bromide combined in solution at three different concentrations and stored in polypropylene syringes at 4 degrees C and 25 degrees C over a period of 15 days. The doses assayed were 20, 60 and 120 mg/day for morphine hydrochloride and 40, 60 and 80 mg/day for hyoscine-N-butyl bromide. These dose ranges were chosen according to daily practice. At both temperatures, all mixtures can be considered as physically compatible since no evidence of incompatibility-that is precipitation, turbidity, colour change or opacity and gas production-were observed. After 15 days of storage, the percentages of hyoscine-N-butyl bromide remaining in the drug mixtures tested ranged between 96.07% and 92.23%. At the end of the study, the percentages of morphine hydrochloride remaining in the drug mixtures were 100% at both temperatures.

Influence of Medium and Temperature on the Hydrolysis Kinetics of Propacetamol Hydrochloride: Determination Using Derivative Spectrophotometry

Propacetamol hydrochloride (PRO) is a water-soluble prodrug of paracetamol (PA) which can be parenterally administered as analgesic for the treatment of postoperative pain, acute trauma, and gastric and/or intestinal disorders where oral administration is not possible. In these circumstances, PRO can be administered in physiologic or glucose solutions since it is rapidly and quantitatively hydrolyzed into PA by plasma estearases. We have studied the degradation kinetics of PRO in 5% glucose and 0.9% saline solutions at 4 degrees C and 25 degrees C (storage and room temperatures, respectively). The analytic technique used to determine PRO and PA quantitatively was first-derivative spectrophotometry. The degradation process of PRO can be best fitted to a second-order kinetics with independence of the medium used (saline or glucose solution). The hydrolysis kinetics of PRO conversion into PA depends on the temperature but not on the assay medium (saline or glucose solution). The degradation rate constants obtained for PRO were approximately 4.5 times higher at 25 degrees C than at 4 degrees C. The values of t(90%) for PRO were 3.17 h and 3.61 h at 25 degrees C, and 13.42 h and 12.36 h at 4 degrees C when the tests were performed in 5% glucose and 0.9% saline solutions, respectively.

Compatibility of haloperidol and hyoscine-N-butyl bromide in mixtures for subcutaneous infusion to cancer patients in palliative care

The administration of drugs by s.c. infusion is routinely practiced in palliative medicine for the management of patients who are no longer able to take oral medication. It is not uncommon for two or more drugs to be combined in s.c. infusion solutions. Unfortunately, the compatibility and stability of haloperidol and hyoscine- N-butyl bromide has not yet been determined. The objective of this study was to study the compatibility and stability of solutions containing both drugs in polypropylene syringes. Nine different solutions were assessed for up to 15 days following preparation. The solutions were prepared in polypropylene syringes with 0.9% saline as a diluent and stored at 4 degrees C and 25 degrees C. High-performance liquid chromatography was the analytical technique used to measure haloperidol and hyoscine- N-butyl bromide. The initial concentration ranges were 0.3125-1.25 mg/ml for haloperidol and 2.5-10.0 mg/ml for hyoscine- N-butyl bromide. Haloperidol was precipitated at a concentration of >/=1.25 mg/ml when it was combined with hyoscine- N-butyl bromide. Concentrations of hyoscine- N-butyl bromide lower than 10 mg/ml in mixtures with haloperidol or 0.625 mg/ml of haloperidol in mixtures with hyoscine- N-butyl bromide for s.c. infusion allow for the administration of both drugs without any significant loss after storage at 25 degrees C for periods of up to 15 days, with approximately >/=90% and 88%, respectively, of haloperidol and hyoscine- N-butyl bromide remaining. However, after storage of the mixtures for equivalent periods at 4 degrees C the losses of hyoscine- N-butyl bromide observed at the end of the study were higher than 20%, while the percentages of haloperidol remaining after 15 days at this temperature were >/=94.37%.

Physical compatibility and in vivo evaluation of drug mixtures for subcutaneous infusion to cancer patients in palliative care

The objectives of this study were first to investigate the compatibility and physical stability of drug admixtures destined for s.c. administration through elastomeric infusion pumps to terminally ill cancer patients followed up at home by staff of the Palliative Care Unit (AECC), "La Paz" Hospital, Madrid and secondly, to evaluate the local side-effects related to the infusion of some of the drug mixtures to a population of 50 patients. The drug mixtures prepared included combinations of two, three, four and five of the following drugs: morphine hydrochloride, 60 mg/day; midazolam hydrochloride, 15 mg/day; haloperidol lactate, 7.5 mg/day; hyoscine-N-butyl-bromide, 60 mg/day; dexamethasone sodium phosphate, 16 mg/day; metoclopramide hydrochloride, 40 mg/day, and tramadol, 400 mg/day. Out of 86 mixtures evaluated in vitro, 52 were found to be physically compatible. Precipitation was always obtained when dexamethasone sodium phosphate at the concentrations assayed was combined with haloperidol lactate and/or midazolam hydrochloride. However, no precipitation occurred when morphine hydrochloride, the opioid most frequently used in patients of this type, and dexamethasone sodium phosphate were combined. Of the drug mixtures that were physically compatible, 18 were administered to the patient population evaluated. Very good symptom control was obtained with all of them, and especially with the mixture of morphine + midazolam + haloperidol + hyoscine, which is the one most frequently administered to cancer patients for palliative care in the final stages of life in our Unit.

Comparative study of the dissolution profiles of a commercial theophylline product after storage

The purpose of this work was to study the effect of storage time and temperature on the in vitro release kinetics of a commercial sustained-release dosage form of theophylline, at different pHs of the dissolution medium. The formulation was stored at 35 degrees C for 16 months and at 45 degrees C for 8 months, with a relative humidity of 60%. The in vitro release tests were performed at pHs 2, 4, 6 and 7.4. The mean values of the transport coefficient n, were close to 0.5 in all the conditions tested, which indicates that the transport system is not modified after storage of the formulation at 35 degrees C and 45 degrees C. The mean values of the dissolution rate constant ranged from 0.036 to 0.043 min(-n), under all the conditions tested. Significant differences (alpha = 0.05) were found between pHs 2, 4 and 6, 7.4 for all the model-independent parameters studied. When the formulation was kept at 35 degrees C for 16 months, the mean percentage of drug dissolved at 8 hours was 25.61% (pHs 2, 4) and, 36.12% (pHs 6, 7.4), representing a 26% and 24% reduction, respectively. Similar results were obtained after storing the formulation at 45 degrees C for 8 months, corresponding to 33.3% (pHs 2, 4) and, 22.5% (pHs 6, 7.4) diminution, respectively. The values of the similarity factor, f2, obtained were lower than 50, which indicates the lack of similarity among the dissolution profiles, after storing the formulation under the experimental conditions tested.

Dissolution rate and in situ intestinal absorption kinetics of guanyl-cysteine

The study of the dissolution behaviour of guanyl-cysteine is presented. The drug was assayed as a pure non-formulated product and formulated in hard gelatine capsules. Aqueous solutions buffered at different pH were used as dissolution fluids. The dissolution rate constant of the drug in this formulation was estimated. Our results show that dissolution of guanyl-cysteine occurs very rapidly. As pH of the dissolution fluid increases, the rate constant slightly decreases. The study of the absorption kinetics of guanyl-cysteine from small intestine of rats was performed with the experimental technique proposed by Doluisio. Six different concentrations of the drug were assayed for the estimation of the absorption rate constant of guanyl-cysteine under our experimental conditions. Our results show that intestinal absorption of the drug occurs as a first-order process.