Investigating emergency nurses' beliefs and experiences with patient handling in the emergency department.

BACKGROUND: Patient handling policy intends to decrease the risk of musculoskeletal injury for nurses. Many factors influence nurses' adherence to patient handling policy, including the context in which the activities take place. The aim of this study was to investigate emergency nurses' beliefs and experiences with patient handling in the emergency department. METHODS: A phenomenological approach was used to explore the participants' experience of patient handling in the ED. Focus group interviews were held in a Victorian emergency department. The interviews were audio-recorded, transcribed, and the data were analysed using thematic analysis. RESULTS: Five interviews were held with 40 nurse participants. Four themes were identified that described participants beliefs and experiences of patient handling: 'Putting the patient first' describes participants prioritisation of patient safety over their own; 'Patient -related challenges' describes the patient factors (e.g. language, mobility, size) that make patient handling more difficult; 'Staff knowledge' of policy and procedure; and 'Inadequate resources' which describes the physical and human resource limitations that made patient handling more difficult. CONCLUSIONS: Issues with equipment, education and patient handling culture are widespread, and this study reaffirms the importance of considering context in developing interventions to improve practice. Introduction of a Safe Patient Handling Program in the ED, that addresses multiple barriers simultaneously, may improve adherence to policy, and reduce the risk of musculoskeletal injury in emergency nurses.

The next generation of liposome delivery systems: recent experience with tumor-targeted, sterically-stabilized immunoliposomes and active-loading gradients.

Three topics are discussed. Enhanced anti-tumor efficacy of targeted doxorubicin-containing sterically-stabilized liposomes using an anti-beta1 integrin Fab' ligand. Use of tumor targeting with an internalizing ligand to improve the efficacy of a non-leaky cisplatin-containing sterically-stabilized liposome formulation. Formulation variables (remote-loading with dextran ammonium sulfate, rigid lipid bilayer) used to optimize in vivo performance of a liposomal camptothecin analog.

Characterization of sterically stabilized cisplatin liposomes by nuclear magnetic resonance.

Extensive scientific efforts are directed towards finding new and improved platinum anticancer agents. A promising approach is the encapsulation of cisplatin in sterically stabilized, long circulating, PEGylated 100 nm liposomes. This liposomal cisplatin (STEALTH cisplatin, formerly known as SPI-77) shows excellent stability in plasma and has a longer circulation time, greater efficacy and lower toxicity than much free cisplatin. However, so far, the physicochemical characterization of STEALTH cisplatin has been limited to size distribution, drug-to-lipid ratio and stability. Information on the physical state of the drug in the liposome aqueous phases and the drug's interaction with the liposome membrane has been lacking. This study was aimed at filling this gap. We report a multinuclear NMR study in which several techniques have been used to assess the physical nature of cisplatin in liposomal formulations and if and to what extent the drug affects the liposome phospholipids. Since NMR detects only the soluble cisplatin in the liposomes and not the insoluble drug, combining NMR and atomic absorption data enables one to determine how much of the encapsulated drug is soluble in the intraliposomal aqueous phase. Our results indicate that almost all of the cisplatin remains intact during the loading process, and that the entire liposomal drug is present in a soluble form in the internal aqueous phase of the liposomes.

Influence of tumour size on uptake of(111)ln-DTPA-labelled pegylated liposomes in a human tumour xenograft model.

The relationship between tumour size and uptake of(111)In-DTPA-labelled pegylated liposomes has been examined in a human head and neck cancer xenograft model in nude mice. The mean tumour uptake of(111)In-labelled pegylated liposomes at 24 hours was 7.2 +/- 6.6% ID/g. Liposome uptake for tumours < 0.1 g, 0.1-1.0 g and > 1.0 g was 15.1 +/- 10.8, 5.9 +/- 2.2 and 3.0 +/- 1.3% ID/g, respectively. An inverse correlation between tumour weight and liposome uptake was observed by both Spearman's rank correlation test (r(s)= - 0.573, P< 0.001) and Pearson's correlation coefficient (r(s)= - 0.555, P< 0.001). For 18 tumours with macroscopic central necrosis, the ratio of uptake in the tumour rim relative to the necrotic tumour core was 11.2 +/- 6.4. Measurement of tumour vascular volume for tumours of various sizes revealed an inverse correlation between tumour weight and tumour vascular volume (Spearman's rank correlation test, r(s)= - 0.598, P< 0.001), consistent with poor or heterogeneous vascularization of larger tumours. These data have important implications for the clinical application of pegylated liposome targeted strategies for solid cancers which are discussed in detail.

Biodistribution and pharmacokinetics of 111In-DTPA-labelled pegylated liposomes in a human tumour xenograft model: implications for novel targeting strategies.

The biodistribution and pharmacokinetics of 111In-DTPA-labelled pegylated liposomes in tumour-bearing nude mice was studied to examine possible applications of pegylated liposome-targeted anti-cancer therapies. Nude mice received an intravenous injection of 100 microl of 111In-DTPA-labelled pegylated liposomes, containing 0.37-0.74 MBq of activity. The t1/2alpha and t1/2beta of 111In-DTPA-labelled pegylated liposomes were 1.1 and 10.3 h, respectively. Tumour uptake was maximal at 24 h at 5.5 +/- 3.0% ID g(-1). Significant reticuloendothelial system uptake was demonstrated with 19.3 +/- 2.8 and 18.8 +/- 4.2% ID g(-1) at 24 h in the liver and spleen, respectively. Other sites of appreciable deposition were the kidney, skin, female reproductive tract and to a lesser extent the gastrointestinal tract. There was no indication of cumulative deposition of pegylated liposomes in the lung, central nervous system, musculoskeletal system, heart or adrenal glands. In contrast, the t1/2alpha and t1/2beta of unencapsulated 111In-DTPA were 5 min and 1.1 h, respectively, with no evidence of accumulation in tumour or normal tissues. Incubation of 111In-DTPA-labelled pegylated liposomes in human serum for up to 10 days confirmed that they are very stable, with only minor leakage of their contents. The potential applications of pegylated liposomes in the arena of targeted therapy of solid cancers are discussed.

Therapy of a xenografted human colonic carcinoma using cisplatin or doxorubicin encapsulated in long-circulating pegylated stealth liposomes.

We compared the therapeutic effects of low doses of cisplatin and doxorubicin hydrochloride encapsulated in long-circulating liposomes composed of cholesterol/hydrogenated soy phosphatidylcholine-polyethylene glycol-distearoyl-phosphatidyl-ethanolamine. The encapsulation of cisplatin and doxorubicin in these liposomes made ineffectively low doses of the free drugs able to inhibit the growth of and affect cures of a human colonic carcinoma growing in nude mice. Liposome-encapsulated cisplatin had minor systemic toxic side effects indicated by an average 9% weight loss which was recovered 3-4 weeks after the last treatment. Toxicity was not observed in mice treated with liposome-encapsulated doxorubicin.

Hyperthermia induces doxorubicin release from long-circulating liposomes and enhances their anti-tumor efficacy.

PURPOSE: To examine the possibility that hyperthermia would accelerate drug release from long-circulating liposomes, and enhance their antitumor activity. METHODS AND MATERIALS: Liposomes were prepared by thin film hydration technique. Hyperthermia was induced by ultrasound apparatus and a water bath heating system. The antitumor efficacy of treatment against RIF-1 tumor in C3H mice was evaluated by the tumor growth delay assay. RESULTS: In vitro drug release experiments demonstrated that increase in temperature from 37 degrees C to 41 degrees C resulted in about a sixfold increase in doxorubicin (DOX) release in a 1-h period. Increasing the temperature to 43 degrees C, resulted in only a modest additional drug release. Drug uptake studies showed that local hyperthermic treatment immediately following the drug administration dramatically enhanced Stealth liposome-encapsulated doxorubicin (S-DOX) uptake by tumors, but did not do so for free DOX. At 42 degrees C and at a dose of 10 mg/kg, the accumulation of S-DOX was about 10-fold and 2.5-fold higher than that with free drug and S-DOX at 37 degrees C, respectively. The antitumor efficacy study confirmed our hypothesis that the addition of hyperthermia to the treatment of RIF-1 tumors with doxorubicin encapsulated in long-circulating liposomes would enhance antitumor effects. Two hyperthermia treatments given at 24-h intervals appeared to be the most promising method of combining heat and long-circulating liposomes. The increased antitumor activity was not accompanied by increased toxicity, as determined by the body weight of the mice. CONCLUSION: Local hyperthermic treatment is able to accelerate DOX release from long-circulating liposomes, increase tumor uptake, and enhance their antitumor efficacy. The combination of local hyperthermia and long-circulating liposomes appears to show considerable promise in the treatment of localized diseases.

Chemoprevention and therapy of mouse mammary carcinomas with doxorubicin encapsulated in sterically stabilized liposomes.

BACKGROUND: The objective of this study was to determine the ability of doxorubicin, encapsulated in sterically stabilized liposomes (Doxil [Liposome Technology, Inc., Menlo Park, CA]), to inhibit the spontaneous development of mammary carcinomas in mice. METHODS: Monthly prophylactic intravenous injections of 6 mg/kg doses of Doxil were started when retired breeding C3H/He mice were 26 weeks old. Mice that developed a mammary carcinoma were then given weekly intravenous injections of 6 mg/kg doses to determine whether the tumors were susceptible or resistant to Doxil therapy. RESULTS: The monthly injections reduced the incidence of first mammary carcinomas in up to 88-week-old retired breeding C3H/He mice from 65 of 66 (98%) in untreated mice to 22 of 47 (47%) in treated mice. The first 15 mice that developed a mammary tumor while on the prophylactic protocol were then placed on a weekly therapeutic protocol. The therapeutic use of Doxil cured 3 of 15 mice and inhibited the growth of 12 tumors. Drug resistance as a result of treatments was not observed. The mean survival of tumor-bearing mice was extended from 24 days in untreated mice to 87 days in treated mice. Toxic side effects were limited to transient weight loss during the weekly Doxil treatments and to epidermal necrosis and dermal fibrosis due to drug extravasation at the sites of intravenous injections. CONCLUSIONS: The authors concluded that doxorubicin in sterically stabilized liposomes deserves to be explored further in comparative studies with free doxorubicin for the prophylaxis and therapy of mammary cancer.

Tissue distribution and therapeutic effect of intravenous free or encapsulated liposomal doxorubicin on human prostate carcinoma xenografts.

BACKGROUND: The authors compared the therapeutic effects of doxorubicin in two formulations: free in saline suspension and encapsulated in sterically stabilized liposomes composed of hydrogenated soy phosphatidylcholine/2cholesterol/polyethylene glycol-distearoyl-phosphatidyl-ethanolamine (Doxil, Liposome Technology, Inc., Menlo Park, CA). METHOD: The drug formulations were injected intravenously to treat human prostate carcinoma PC-3, implanted subcutaneously into nude Swiss mice. Confocal laser scan microscopy and microfluorometry were used to determine tissue distribution and to quantitate drug uptake. RESULTS: Laser scan microscope and microfluorometer studies showed that the liposome-encapsulated drug entered the liver, the kidneys, and the tumor in greater quantity and remained in the liver and in the tumor longer than the free drug. The liposome formulation produced a 25-fold increase in doxorubicin at the disease site. Doxil was significantly more effective than the free drug in inhibiting growth and in effecting cures and had only minor and temporary systemic toxic effects. CONCLUSIONS: The current study demonstrated the therapeutic efficacy of doxorubicin, encapsulated in sterically stabilized liposomes, against prostate carcinoma. Decreased systemic elimination, increased penetration into the tumor, and long liposome presence with slow drug release into the tumor probably accounted for the enhanced therapeutic effect of doxorubicin in sterically stabilized liposomes.

Therapy of human ovarian carcinoma xenografts using doxorubicin encapsulated in sterically stabilized liposomes.

BACKGROUND: This study compared the therapeutic effects of doxorubicin hydrochloride in saline and in sterically stabilized, long-circulating liposomes composed of hydrogenated soy phosphatidylcholine/cholesterol/polyethylene glycol-distearoyl-phosphatidyl-ethanolamine (Doxil). METHODS: The drug formulations were injected intravenously or intraperitoneally to treat the human ovarian carcinoma HEY, which was implanted subcutaneously or intraperitoneally into mature female Swiss nude mice. RESULTS: The long-circulating liposome formulation was significantly more effective than was the free drug in inhibiting tumor growth and in producing cure. The liposome formulation was significantly less toxic than was the free drug. This is the first demonstration of the therapeutic effectiveness of doxorubicin in sterically stabilized liposomes against human tumor xenografts. CONCLUSIONS: The encapsulation of doxorubicin in long-circulating liposomes significantly enhanced the therapeutic efficacy of the drug against a human ovarian carcinoma.

Factors affecting the release rate of terbutaline from liposome formulations after intratracheal instillation in the guinea pig.

Maximum duration of bronchodilator efficacy in inhaled liposome-based formulations depends on optimizing the in vivo release rate of the encapsulated bronchodilator. We investigated the effect of several formulation variables on the pulmonary residence time of 3H-terbutaline sulfate liposomes administered intratracheally in guinea pigs, using an improved method enabling the measurement of pulmonary drug absorption for extended periods of time in conscious animals. Half-lives of liposome-encapsulated 3H-terbutaline disappearance from the lungs and airways after instillation ranged from 1.4 to 18 hr and were markedly affected by liposome size, cholesterol content, and phospholipid composition. This study demonstrates that liposomes can significantly prolong the residence time of bronchodilators in the lungs and that precise control over the pulmonary residence time of encapsulated bronchodilators can be achieved by controlling formulation variables.

Clearance of phosphatidylcholine and cholesterol from liposomes, liposomes loaded with metaproterenol, and rabbit surfactant from adult rabbit lungs.

Rabbits were given by tracheal instillation liposomes, liposomes carrying metaproterenol sulfate (MPS) and suspended in a MPS solution, rabbit surfactant, or rabbit surfactant suspended in a MPS solution. The lipid suspensions were labeled with [14C]cholesterol and [3H]phosphatidylcholine. The percent recoveries of the labels were measured over 24 h in alveolar wash, lung tissue after alveolar wash, and the total lungs. All clearance curves for both phosphatidylcholine and cholesterol from liposomes were the same in the presence or absence of MPS. Alveolar clearance curves for both labels from rabbit surfactant were the same; however, the surfactant-associated labels were cleared to the lung tissue more rapidly than were the liposome-derived labels. Despite different alveolar clearance curves, all clearance curves for cholesterol from the total lungs were similar at a rate of 20 to 30%/24 h of the injected labeled cholesterol. Phosphatidylcholine was cleared from the total lungs more rapidly, at rates from 35 to 56%/24 h. Although MPS did not change labeled liposomal lipid clearance, the beta-agonist increased surfactant lipid clearance. The different responses to beta-agonist and the different alveolar clearance curves indicated distinct alveolar-to-lung tissue metabolism for liposomal versus surfactant phosphatidylcholine and cholesterol, although overall lung clearance rates were similar.

Liposome disposition in vivo. VI: Delivery to the lung.

The effect of negatively charged liposome components and vesicle size on the time course and dose dependency of liposome disposition in mice was studied with a view to optimizing liposome delivery to the lung. The disposition of large multilamellar liposomes was followed using 125I-labeled p-hydroxybenzamidine phosphatidyl ethanolamine. Of the three negatively charged liposome compositions studied (phosphatidyl choline-X-cholesterol-alpha-tocopherol, molar ratio: 4:1:5:0.1; X = phosphatidyl serine, dipalmitoyl phosphatidic acid, or phosphatidyl glycerol), phosphatidyl serine liposomes resulted in the greatest accumulation in lungs. Lung levels decreased up to 95 h postdose, at which time 6% of the liposome dose present at 2 h still remained. The disposition of phosphatidyl serine-containing liposomes was independent of dose for the range 0.04-21 mumol/animal. When liposomes containing phosphatidyl choline were prepared using a variety of extrusion and dialysis conditions, a strong link between liposome size and lung accumulation was revealed. A maximum lung accumulation of 30.9% of the administered dose was achieved with no detectable gross pathological lung lesions up to 24 h postdose.

Delivery of therapeutic doses of doxorubicin to the mouse lung using lung-accumulating liposomes proves unsuccessful.

Addition of solid doxorubicin or solutions to pre-formed liposomes proved to be the optimal method for incorporating the drug into liposomes whilst maintaining their size distribution and hence ability to accumulate in the lung. Liposomes prepared in this way lost doxorubicin only slowly on dialysis but dilution with an equal volume of saline at 37 degrees C resulted in the loss of 80% of the incorporated doxorubicin within 30 min. These liposomes were thus ineffective in altering doxorubicin disposition in vivo and produced no enhanced activity compared with free drug and a non-lung-accumulating carrier liposome in the EMT6 cell-Balb/c mouse model lung tumour.

The use of a new radioactive-iodine labeled lipid marker to follow in vivo disposition of liposomes: comparison with an encapsulated aqueous space marker.

The in vivo disposition of multilamellar liposomes extruded at 0.6 micrometers (PC/DPPA/CH/ alpha-T = 4:1:5:0.1 molar ratio) when injected i.v. into mice has been examined utilizing a novel iodinatable phospholipid derivative as a lipid phase marker (p-hydroxybenzamidine phosphatidylethanolamine: 125I-BPE) and compared to that using 14C-inulin as an aqueous phase marker. At times up to 5 h post-dose the disposition of both markers was essentially identical with the exception of blood and intestine, where 125I-BPE levels were consistently higher than 14C-inulin levels. At time intervals from 5-72 h post-dose 125I-BPE levels in all the organs examined were lower than those of 14C-inulin. These differences in the behaviour of the two labels may be explained in terms of exchange of the iodinated lipids, excretion of released inulin and long term metabolism of the lipid marker. We conclude tha 125I-BPE is a useful marker for following liposome disposition in short-term studies particularly in view of the easily quantifiable nature of gamma-radioactivity which obviates the need for sample preparation.

Liposome disposition in vivo IV: the interaction of sequential doses of liposomes having different diameters.

In order to evaluate the degree to which liposomes of the same composition but of different size interact with organ binding sites, a series of pre-dose studies have been carried out in mice. Two sizes of multilamellar liposomes were used: large (L) liposomes averaging 0.5 micrometer in diameter and small (S) liposomes averaging 0.06 micrometer in diameter. Lipid composition was phosphatidylcholine/phosphatidic acid/cholesterol/alpha-tocopherol in the molar ratio 4:1:5:0.1. Experiments consisted of a saturating pre-dose of either non-radioactive L- or S-liposomes followed at various times by a test dose of radioactively labelled L- or S-liposomes. When pre-dose and test dose were of the same diameter, an interaction was observed. A pre-dose of L-liposomes also interacted with a test dose of S-liposomes but a pre-dose of S-liposomes did not interact with a test dose of L-liposomes. All disposition effects were reversible, returning to control values within 24 h. These results indicate that L- and S-liposomes of identical composition may associate with different hepatic binding sites and that a class of non-specific binding sites available to S-liposomes but not to L-liposomes may exist.

Liposome disposition in vivo. III. Dose and vesicle-size effects.

The effect of lipid dose (4,3-512.8 mumol total lipid/kg body weight), administered intravenously as liposomes encapsulating radioactive inulin, upon the ability of mouse organs to bind and/or take-up the radioactive label has been studied in vivo. Three different liposome diameters were investigated: 0.46 micrometers (L), 0.16 micrometers (M) and 0.058 micrometers(S). All liposomes were negatively charged with lipid composition of phosphatidylcholine/phosphatidic acid/cholesterol/alpha-tocopherol in the molar ration 4 : 1 : 5 : 0.1 or 4 : 1 : 1 : 0.05. Overall radioactive label disposition after 2 h was consistent with localization predominantly in the reticuloendothelial system. A saturation of liver with increasing lipid dose was demonstrated for all three sizes, together with a corresponding increase in blood levels. Spleen radioactivity increased with increasing dose of L- and M-liposomes, but decreased for increasing doses of S-liposomes. Levels in residual carcass exhibited no trend. It was noted that by adjusting liposomal lipid dose and vesicle diameter the percentage of administered dose present in blood could be varied 733-fold, that in spleen 9-fold, liver 4-fold. Stability in vivo was ranked L greater than M greater than S-liposomes. Correction for differences of in vivo stability reduced the differences in organ accumulation between the three liposome sizes. The organ accumulation pattern suggested a dose- and diameter-dependent mechanism for liposome disposition. It was expected that when doses of fixed liposome composition were expressed as number of liposomes or their total surface area, organ saturation patterns would be similar. However, re-plotting the percent dose values for liver and spleen versus the number of liposomes administered revealed a saturation pattern for L-, M- and S-liposomes which was different in each case. Plotting the data versus the total surface area of the dose revealed a similar disposition pattern for L-, M- and S-liposomes in liver and L- and M-liposomes in spleen. The data indicate that in addition to composition, the lipid dose, total liposomal surface area and effective mean diameter are important pharmacokinetic variables. Further, the optimization of the therapeutic index of an encapsulated agent or target-tissue delivery via liposomes will require consideration of both the surface area and diameter of the liposome doses together with liposome composition.

Liposome disposition in vivo: effects of pre-dosing with lipsomes.

The effect of a high, intravenous dose of extruded multilamellar liposomes (1.1 g lipid/kg body weight) upon the subsequent ability of mouse tissues to take-up or bind a second intravenous dose of similar liposomes encapsulating 14C-inulin has been studied in vivo. The first and second doses were separated by either 1,5 or 24 hours. All tissue levels were measured one hour after the second dose. Controls received only the second dose. When the two doses were separated by one hours, 14C-levels in liver were depressed 6-fold and blood levels rose 29-fold relative to controls. However spleen uptake of lipsomes increased to three times control levels. When the two doses were separated by 24 hrs, the first dose had only a minimal effect on the disposition of the second dose. The results are consistent with a reversible blockade of hepatic, but not spleenic uptake and/or binding sites, by the first dose and indicate that adjusting a liposome dose (i.e. number of lipsomes) or use of a drug-free liposome pre-dose may be a useful technique for reducing hepatic uptake, increasing the circulation life time and/or modifying the tissue disposition properteries of therapeutic liposomes without changing liposome composition or size.

Some characteristics of sn-glycero-3-phosphocholine diesterases from rat brain.

1. sn-Glycero-3-phosphocholine diesterase activities, glycerophosphohydrolase (EC 3.1.4.2) and choline phosphohydrolase (EC 3.1.4.38) from rat brain have been partially purified and characterized using sn-glycere-3-[32P]phosphocholine as substrate and separating the reaction products by anion-exchange chromatography and ionophoresis. 2. Rat brain contained particulate (75%) and soluble (25%) activity from both diesterases. No difference in pH optimum or metal ion requirement for the particulate compared to the soluble enzymes was observed. 3. Glycerophosphohydrolase (EC 3.1.4.2) was purified 60-fold, choline phosphohydrolase (EC E.1.4.38) 120-fold from rat brain supernatant fraction by DEAE-cellulose ion-exchange chromatography and sucrose density gradient centrifugation. The density gradient results in conjunction with dodecyl sulphate-polyacrylamide gel disc electrophoresis yielded molecular weight estimates of 230 000 (monomer 62 000) for choline phosphohydrolase and 120 000 (monomer 70 000) for glycerophosphohydrolase (EC 3.1.4.2). 4. Glycerophosphohydrolase (EC 3.1.4.2) has a pH optimum of 8.9 and a Km for sn-glycero-3-phosphocholine of 0.6 mM. The enzyme is inhibited by EDTA and reactivated by Ca2+. Choline phosphohydrolase (EC 3.1.4.38) has pH optimum 10.5, a Km of 2 mM and is unaffected by EDTA. Both enzymes require Ca2+ for maximum activity.