Multidimensional analysis of human intestinal fluid composition

The oral administration of solid dosage forms is the commonest method to achieve systemic therapy and relies on the drug's solubility in human intestinal fluid (HIF), a key factor that influences bioavailability and biopharmaceutical classification. However, HIF is difficult to obtain and is known to be variable, which has led to the development of a range of simulated intestinal fluid (SIF) systems to determine drug solubility in vitro. In this study we have applied a novel multidimensional approach to analyse and characterise HIF composition using a published data set in both fasted and fed states with a view to refining the existing SIF approaches. The data set provided 152 and 172 measurements of five variables (total bile salt, phospholipid, total free fatty acid, cholesterol and pH) in time-dependent HIF samples from 20 volunteers in the fasted and fed state, respectively. The variable data sets for both fasted state and fed state are complex, do not follow normal distributions but the amphiphilic variable concentrations are correlated. When plotted 2-dimensionally a generally ellipsoid shaped data cloud with a positive slope is revealed with boundaries that enclose published fasted or fed HIF compositions. The data cloud also encloses the majority of fasted state and fed state SIF recipes and illustrates that the structured nature of design of experiment (DoE) approaches does not optimally cover the variable space and may examine media compositions that are not biorelevant. A principal component analysis in either fasted or fed state in combination with fitting an ellipsoid shape to enclose the data results in 8 points that capture over 95% of the compositional variability of HIF. The variable's average rate of concentration change in both fasted state and fed state over a short time scale (10 min) is zero and a Euclidean analysis highlights differences between the fasted and fed states and among individual volunteers. The results indicate that a 9-point DoE (8 + 1 central point) could be applied to investigate drug solubility in vitro and provide statistical solubility limits. In addition, a single point could provide a worst-case solubility measurement to define the lowest biopharmaceutical classification boundary or for use during drug development. This study has provided a novel description of HIF composition. The approach could be expanded in multiple ways by incorporation of further data sets to improve the statistical coverage or to cover specific patient groups (e.g., paediatric). Further development might also be possible to analyse information on the time dependent behaviour of HIF and to guide HIF sampling and analysis protocols.

A technique for transcervical intrauterine insemination of ewes

In commercial artificial insemination (AI) of sheep, fresh extended semen is deposited into the vagina or cervical os, or fresh extended or frozen semen is placed laparoscopically into the uterus. Transcervical intrauterine insemination of the ewe is not used commercially. In this study, methods of restraint and instrumentation for AI were evaluated and modified to produce a transcervical intrauterine technique suitable for commercial application. Four methods of restraint, four vaginal specula, three forceps and four instruments suitable for transcervical passage were compared. From these comparisons a technique was developed in which the ewes were positioned in dorsal recumbency with their hindquarters elevated. The vagina was dilated using a duck-billed speculum, the cervix was grasped and retracted using forceps, and an inseminating instrument was introduced into the cervical opening and manipulated through the cervical canal. The technique was repeated on 89 mature, multiparous ewes: the difficulty in locating the cervical opening, the force required to retract the cervix and the time required to penetrate into the uterus were recorded. Uterine penetration was achieved in 82% of the ewes. This technique has the potential to be applied in commercial artificial insemination programs of sheep.

Maintaining a frozen shipping environment for Phase I clinical trial distribution

The need for stringent temperature control provides significant challenges to pharmaceutical distributors operating in all sectors of the industry. Products with a frozen storage label requirement can be significantly problematic. This study aimed to provide evidence of robust and reproducible frozen shipment arrangements to be operated by a Phase I clinical trial unit. Dry ice was used to achieve a deep frozen internal parcel environment and was tested in a laboratory setting using ultra low temperature loggers within dummy product packs within the test parcels. The laboratory dry ice packing configuration was then repeatedly tested in real time transits using a Glasgow to London delivery schedule. An internal temperature specification was set to not exceed -10 degrees C during the transport. During each delivery, external temperature monitoring measured the temperature stress experienced by the box in transit. Results demonstrated the ability of the chosen system to not exceed -13.6 degrees C on average (-10 degrees C maximum) when exposed to external temperatures of up to +20.1 degrees C (mean kinetic temperature). The effect was maintained for at least 52.5h.

Maintaining the cold chain shipping environment for Phase I clinical trial distribution

The study aimed to demonstrate satisfactory inter-UK transit of cold storage clinical trial material. The product environment had to be maintained between 0 and 8 degrees C throughout transit until delivery. Straightforward, low cost and simplified shipping arrangements were sought that would be appropriate for small-scale Phase I clinical trial activities. A laboratory test defined an optimal three frozen gel pack configuration to maintain refrigerated environmental conditions for dummy product packs in a single type and size of insulated shipper. The internal environment was temperature monitored at 30-min intervals in all tests. Twelve Glasgow to London transits were then studied over 2 years to include all seasonal temperature variations. A configuration using three frozen gel packs and 4 h pre-chill of the transit container maintained the internal environment at 0-8 degrees C for up to 48 h during autumn, winter and spring. A modified four frozen gel pack configuration was suitable for summer transit. Thus cold shipment verification was successfully carried out for a small-scale distribution operation. It was proven that refrigerated shipping conditions could be maintained using a straightforward and cost effective 'passive' type system consisting of frozen gel packs and insulated transit containers.

A Cancer Research (UK) randomized phase II study of idoxifene in patients with locally advanced/metastatic breast cancer resistant to tamoxifen

Idoxifene is a novel selective oestrogen receptor modulator (SERM) which had greater binding affinity for the oestrogen receptor (ER) and reduced agonist activity compared with tamoxifen in preclinical studies. In a randomized phase II trial in 56 postmenopausal patients with progressive locally advanced/metastatic breast cancer we assessed whether idoxifene showed evidence of activity compared with an increased 40 mg/day dose of tamoxifen in patients who had previously demonstrated resistance to the standard 20 mg/day dose of tamoxifen. Of 47 patients eligible for response (25 idoxifene, 22 tamoxifen), two partial responses and two disease stabilizations (SD) for >6 months were seen with idoxifene (overall clinical benefit rate 16%, 95% CI 4.5-36.1%). The median duration of clinical benefit was 9.8 months. In contrast, no objective responses were seen with the increased 40 mg/day dose of tamoxifen, although two patients had SD for 7 and 14 months (clinical benefit rate 9%, 95% CI 1.1-29.2%). Idoxifene was well tolerated and the reported possible drug-related toxicities were similar in frequency to those with tamoxifen (hot flushes 13% vs 15%, mild nausea 20% vs 15%). Endocrine and lipid analysis in both groups showed a similar significant fall in serum follicle-stimulating hormone and luteinizing hormone after 4 weeks, together with a significant rise in sex hormone binding globulin levels and 11% reduction in serum cholesterol levels. In conclusion, while idoxifene was associated with only modest evidence of clinical activity in patients with tamoxifen-resistant breast cancer, its toxicity profile and effects on endocrine/lipid parameters were similar to those of tamoxifen.

Use of mathematical derivatives (time-domain differentiation) on chromatographic data to enhance the detection and quantification of an unknown 'rider' peak

Two samples of an anticancer prodrug, AQ4N, were submitted for HPLC assay and showed an unidentified impurity that eluted as a 'rider' on the tail of the main peak. Mathematical derivatization of the chromatograms offered several advantages over conventional skimmed integration. A combination of the second derivative amplitude and simple linear regression gave a novel method for estimating the true peak area of the impurity peak. All the calculation steps were carried out using a widely available spreadsheet program.

Clinical aspects of a phase I trial of 5,6-dimethylxanthenone-4-acetic acid (DMXAA), a novel antivascular agent

The antitumour action of 5,6-dimethylxanthenone-4-acetic acid (DMXAA) is mediated through tumour-selective antivascular effects and cytokine induction. This clinical phase I trial was conducted to examine its toxicity, maximum tolerated dose, pharmacokinetics (PK) and pharmacodynamics (PD). A secondary objective was to assess its antitumour efficacy. DMXAA was administered every 3 weeks as a 20-min i.v. infusion. Dose escalation initially followed a modified Fibonacci schema but was also guided by PK and toxicity. A total of 63 patients received 161 courses of DMXAA over 19 dose levels ranging from 6 to 4900 mg m(-2). DMXAA was well tolerated at lower doses and no drug-related myelosuppression was seen. Rapidly reversible dose-limiting toxicities were observed at 4900 mg m(-2), including confusion, tremor, slurred speech, visual disturbance, anxiety, urinary incontinence and possible left ventricular failure. Transient prolongation of the corrected cardiac QT interval was seen in 13 patients evaluated at doses of 2000 mg m(-2) and above. A patient with metastatic cervical carcinoma achieved an unconfirmed partial response at 1100 mg m(-2), progressing after eight courses. The results of PK and PD studies are reported separately. DMXAA has antitumour activity at well-tolerated doses.

Development of a lyophilised RH1 formulation: a novel DT diaphorase activated alkylating agent

RH1 is a novel aziridinylbenzoquinone alkylating agent, which is activated in tumour cells by DT diaphorase. In common with previous aziridinylbenzoquinones, RH1 exhibits limited aqueous stability and solubility. The aim of this study was to examine the pharmaceutical properties of RH1 with a view to preparing a suitable formulation for clinical trial. Stability in a neutral phosphate-buffered solution was poor with a degradation half-life of 50 h at 55 degrees C, indicating that lyophilisation was preferable. The reaction kinetics indicated a similarity with previous studies for base-catalysed degradation of aziridinylbenzoquinones. Intrinsic aqueous solubility at 0.5 mg mL(-1) may be increased in solvent systems or by the use of polymers such as polyvinylpyrrolidone (PVP) or complexing agents like hydroxypropyl-beta-cyclodextrin (HPBCD). In the latter case this increased solubility by an order of magnitude to around 5 mg mL(-1). Four potential formulations based on lyophilisation of RH1 (1 mg mL(-1)) from buffered solution (pH 7, 0.01 M NaH2PO4) containing either 50 mg mL(-1) mannitol, 40 mg mL(-1) dextran, 20 mg mL(-1) PVP or 50 mg mL(-1) HPBCD were prepared and examined for stability characteristics. All formulations exhibited a temperature-dependent degradation. The mannitol and dextran formulations had limited stability and degraded rapidly at all temperatures. The PVP and HPBCD formulations degraded at elevated temperatures but remained stable for up to twelve months at 4 degrees C. Examination of the degradation kinetics in the latter systems demonstrated similarity to the solution degradation mechanism, while in the former alternative degradation pathways appeared to be occurring. The chemical stability of RH1 in lyophilised formulations is dependent upon the excipient employed and storage temperature. Either the PVP or HPBCD formulation would be suitable clinical trial formulations of RH1. The results indicate that the choice of lyophilisation excipient for aziridinylbenzoquinones cannot be based on previous literature studies of related agents.

A synthetic low density lipoprotein particle capable of supporting U937 proliferation in vitro

A synthetic LDL (sLDL) has been prepared by combining a lipid microemulsion with amphipathic peptides containing the apoprotein B receptor domain. The biological properties of sLDL have been investigated using the U937 in vitro cell proliferation assay. sLDL exhibits a concentration dependent and saturable stimulation of U937 proliferation. By utilizing different amphipathic peptides, variable proliferation is achieved, indicating a specific interaction between sLDL and the U937 LDL receptor are possible. U937 proliferation is reduced by the addition of an anti-LDL receptor antibody, indicating that sLDL is assimilated via the LDL receptor pathway. The behavior of sLDL mimics that of native LDL, and this approach represents a viable technique for the production of an sLDL particle on a large scale for research and general application.

Physicochemical properties of microemulsion analogues of low density lipoprotein containing amphiphatic apoprotein B receptor sequences

Low density lipoprotein (LDL) has been proposed as a drug targeting vector in cancer chemotherapy, however, research has been limited due to the necessity to isolate material from plasma. In this study, the physicochemical properties of synthetic lipid microemulsions containing an amphiphatic version of the apoprotein B receptor binding sequence have been examined. The effect of peptide sequence length, lipid anchor type and location along with microemulsion lipid composition were investigated via changes in particle size and zeta potential. Size increases were related to the amphiphatic peptides lipophilic portion and too a lesser extent by amino acid sequence length. Two lipophilic anchors, retinoic acid and cholesterol, produced large size increases whilst a single anchor (retinoic acid) did not affect size. The amphiphatic peptide reversed measured zeta potential from negative to positive values in a concentration dependent manner. This was related to peptide structure and could be effected by changes in pH, indicating that the peptide was surface located and responsive to the external environment. Alteration of microemulsion lipid composition also affected physicochemical properties but to a lesser degree than changes in the amphiphatic peptide. These novel systems may represent a useful synthetic alternative to native LDL for a variety of applications.

The in vitro cell association of invasin coated polylactide-co-glycolide nanoparticles

PURPOSE

To determine the effect of particle size and ligand surface density on the cellular association of poly lactide-co-glycolide nanoparticles covalently coated with bacterial invasin.

METHODS

Poly lactide-co-glycolide nanoparticles containing a flourescent probe were prepared at four diameters 155 nm, 200 nm, 375 nm and 600 nm using standard techniques. Bacterial invasin was covalently coupled to the particles surface at varying surface concentrations using a water soluble carbodiimide. The modified particle's cellular association with HEp2 2B cells in tissue culture was determined using flow cytometry.

RESULTS

Cellular association of modified nanoparticles was time dependent, abolished at low temperature, competitively inhibited by free invasin or the RGD peptide ligand and saturable. Increased cell association was produced by increasing the particle's surface invasin concentration however, this effect was size dependent. Small particles (155 nm and 200 nm) exhibiting a maximal association with increasing invasin concentration whilst the larger particles (375 nm and 600 nm) provide a minimum at low invasin concentrations.

CONCLUSIONS

Modified particle cell association provided results commensurate with a receptor dependent uptake mechanism related to the presence of invasin. The size and surface concentration dependency however illustrate that application of these ligands to particulate drug delivery or targeting systems will be controlled by their natural cellular association properties.

Phase I and pharmacokinetic study of D-limonene in patients with advanced cancer. Cancer Research Campaign Phase I/II Clinical Trials Committee

PURPOSE

D-Limonene is a natural monoterpene with pronounced chemotherapeutic activity and minimal toxicity in preclinical studies. A phase I clinical trial to assess toxicity, the maximum tolerated dose (MTD) and pharmacokinetics in patients with advanced cancer was followed by a limited phase II evaluation in breast cancer.

METHODS

A group of 32 patients with refractory solid tumors completed 99 courses of D-limonene 0.5 to 12 g/m2 per day administered orally in 21-day cycles. Pharmacokinetics were analyzed by liquid chromatography-mass spectrometry. Ten additional breast cancer patients received 15 cycles of D-limonene at 8 g/m2 per day. Intratumoral monoterpene levels were measured in two patients.

RESULTS

The MTD was 8 g/m2 per day; nausea, vomiting and diarrhea were dose limiting. One partial response in a breast cancer patient on 8 g/m2 per day was maintained for 11 months; three patients with colorectal carcinoma had prolonged stable disease. There were no responses in the phase II study. Peak plasma concentration (Cmax) for D-limonene ranged from 10.8+/-6.7 to 20.5+/-11.2 microM. Predominant circulating metabolites were perillic acid (Cmax 20.7+/-13.2 to 71+/-29.3 microM), dihydroperillic acid (Cmax 16.6+/-7.9 to 28.1+/-3.1 microM), limonene-1,2-diol (Cmax 10.1+/-8 to 20.7+/-8.6 microM), uroterpenol (Cmax 14.3+/-1.5 to 45.1+/-1.8 microM), and an isomer of perillic acid. Both isomers of perillic acid, and cis and trans isomers of dihydroperillic acid were in urine hydrolysates. Intratumoral levels of D-limonene and uroterpenol exceeded the corresponding plasma levels. Other metabolites were trace constituents in tissue.

CONCLUSIONS

D-Limonene is well tolerated in cancer patients at doses which may have clinical activity. The favorable toxicity profile supports further clinical evaluation.

Pre-clinical development of the anti-tumour agent CB 7646, bis N-(hydroxymethyl) trimethylmelamine, a stable analogue of trimelamol

Formulation difficulties prevented the otherwise promising clinical development of the anti-tumour agent trimelamol (TM; tris-[hydroxymethyl]trimethylmelamine]). A synthetic analogue programme resulted in the identification of CB 7646 (bis N-[hydroxymethyl]trimethylmelamine) as a compound with improved stability and favourable formulation characteristics. The in vitro and in vivo activity of CB 7646 was shown to be very similar to that of TM. In addition, curative activities were shown in the PXN/65 human ovarian cancer xenograft and the MX-1 and T-61 human breast cancer xenograft models. The effectiveness of the N-(hydroxymethyl)melamines against platinum-refractory disease was noted in the phase I clinical trial of TM. In line with this finding, the present study confirmed the effective activity of both TM and CB 7646 against various forms of platinum resistance in in vitro models. Curative activity for TM and CB 7646 was seen in the HX110P human ovarian cancer xenograft with acquired carboplatin resistance. Animal studies indicated less neurotoxicity for CB 7646 than for TM. The pharmacokinetic profile of CB 7646 indicated a decreased plasma elimination, indicative of slower in vivo degradation than for TM. CB 7646, therefore, represents a promising candidate for clinical development, designed to supersede TM.

CRC/EORTC/NCI Joint Formulation Working Party: experiences in the formulation of investigational cytotoxic drugs

The pharmaceutical formulation of a new anti-tumour agent has often been perceived as the bottleneck in anti-cancer drug development. In order to increase the speed of this essential development step, the Cancer Research Campaign (CRC), the European Organization for Research and Treatment of Cancer (EORTC) and the National Cancer Institute (NCI) agreed in 1987 to form the Joint Formulation Working Party (JFWP). The main goal of the JFWP is to facilitate the rapid progress of a new drug through pharmaceutical developmental to preclinical toxicology and subsequently to phase I clinical trial. Under the auspices of the JFWP around 50 new agents have been developed or are currently in development. In this report we present our formulation experiences since the establishment of the JFWP with a selected number of agents: aphidicolin glycinate, bryostatin 1, carmethizole, carzelesin, combretastatin A4, dabis maleate, disulphonated aluminium phthalocyanine, E.O.9, 4-hydroxyanisole, pancratistatin, rhizoxin, Springer pro-drug, SRI 62-834, temozolomide, trimelamol and V489. The approaches used and problems presented may be of general interest to scientists in related fields and those considering submitting agents for development.

Conversion of mitomycin C to 2,7-diaminomitosene and 10-decarbamoyl 2,7-diaminomitosene in tumour tissue in vivo

The progress of mitomycin C (MMC) bioreduction was studied in vivo in the rat Sp 107 mammary carcinoma after intra-tumoural injection of either 100 micrograms or 1 mg. 2,7-Diaminomitosene (2,7-DM) was utilised as a primary bioreductive metabolite and 10-decarbamoyl 2,7-diaminomitosene (DC 2,7-DM) served as a secondary bioreductive metabolite, both of which were measured by high-performance liquid chromatography. 2,7-DM and DC 2,7-DM were produced rapidly, achieving close to their maximal concentrations at the earliest time point studied [5 min]. 2,7-DM was cleared rapidly from the tumour with apparent half-lives of 5 and 35 min after the low and high drug doses, respectively. DC 2,7-DM had a longer apparent half-life of 130 min at the higher dose but, as compared with 2,7-DM, was only a minor metabolite [the area under the curve (AUC) of 2,7-DM was 5.6-fold that of DC 2,7-DM]. At the lower drug dose, DC 2,7-DM was not detectable. Rapid formation and disappearance of bioreductive metabolites of MMC may account for the failure of previous studies to detect these products in vivo.

Determination of mitomycin C, 2,7-diaminomitosene, 1,2-cis- and 1,2-trans-1-hydroxy-2,7-diaminomitosene in tumour tissue by high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the determination of mitomycin C (MMC) and its metabolites 2,7-diaminomitosene (2,7-DM), 1,2-cis-1-hydroxy-2,7-diaminomitosene (cis-hydro) and 1,2-trans-1-hydroxy-2,7-diaminomitosene (trans-hydro) in tumour tissue. N-la-Methylmitomycin C (porfiromycin, PM) was used as an internal standard. Two factors were critical in resolving the metabolites: pH and buffer ionic strength, where the retention times of the four components were affected in the order 2,7-DM >> cis-hydro >> trans-hydro >> MMC. The optimal isocratic conditions (flow-rate 1 ml/min) were 18 mM sodium phosphate pH 5.8-methanol (74:26) and a column temperature of 40 degrees C on a Spherisorb ODS-2 column (25 cm x 4.6 mm I.D.). Liquid-liquid extraction [twice with chloroform-propan-2-ol-ethyl acetate (2:2:1)] is described for tumour tissue. Recoveries varied depending on the component: MMC, 71.9 +/- 12.4%; PM, 85.5 +/- 27%; 2,7-DM, 51.7 +/- 5.4%; cis-hydro, 52.0 +/- 16.8%; trans-hydro, 62 +/- 8%. When applied to the analysis of a rat mammary carcinoma treated intra-tumourally with 450 micrograms of MMC five drug-related "metabolite" peaks were detected. Three of these co-chromatographed with standards of 2,7-DM, cis- and trans-hydro, and had identical absorption maxima to their respective standards, with the possible exception of trans-hydro.

Doxorubicin-loaded casein microspheres: protein nature of drug incorporation

We have studied incorporation of [14C]doxorubicin within protease-sensitive casein microspheres both by 14C-activity, measuring total drug, and HPLC, measuring free drug only. It was found that total drug content (27.7 micrograms mg-1) exceeded free drug content (3.2 micrograms mg-1) suggesting that the major portion of doxorubicin was incorporated via a covalent linkage to matrix protein. In-vivo drug disposition and activity studies suggested that this fraction of doxorubicin was the major species within tumour tissue (total vs free: 5 min, 14.3 micrograms g-1 vs 0.7 micrograms g-1; 24 h, 11.7 micrograms g-1 vs 1.1 micrograms g-1; 48 h, 11.2 micrograms g-1 vs 1.2 micrograms g-1; 72 h, 10.0 micrograms g-1 vs 0.8 micrograms g-1), did not exhibit a 'burst' effect, was slowly cleared (30% loss over 3 days), and was equiactive (growth delay = 12 days) compared with drug in solution (growth delay = 10 days). This work clearly implicates in-vivo microsphere matrix biodegradation in drug release and subsequent disposition and activity.

The effect of intravenous pretreatment with small liposomes on the pharmacokinetics and metabolism of antipyrine in rabbits

The effect of intravenous pre-treatment with empty small liposomes on the pharmacokinetics and metabolism of antipyrine in rabbits has been investigated. The measured half-life of antipyrine was 104 min and the volume of distribution was 830 mL kg-1. The excretion of metabolites in a 24 h urine sample was measured, the main metabolite 4-hydroxyantipyrine was excreted to a level of 10% with the free drug accounting for 4%. The norantipyrine and 3-hydroxymethylantipyrine metabolites were excreted to a level of 8 and 7%, respectively. The intravenous administration of liposomes at a dose equivalent to 8 mg of egg yolk phosphatidylcholine daily for one week, had no significant effect on any of the measured pharmacokinetic parameters. The half-life after liposome treatment was 110 min and the volume of distribution was 790 mL kg-1, the metabolic pattern in the urine was also unaltered. The results suggest that the repeated administration of low doses of liposomes do not affect the pharmacokinetics and metabolism of antipyrine.

Nanoparticle uptake by the rat gastrointestinal mucosa: quantitation and particle size dependency

Polystyrene microspheres in the size range 50 nm to 3 microns were fed by gavage to female Sprague Dawley rats daily for 10 days at a dose of 1.25 mg/kg-1. Previous histological evidence of the uptake of these particles and their absorption across the gastrointestinal tract and passage via the mesentery lymph supply and lymph nodes to the liver and spleen was confirmed by analysis of tissues for the presence of polystyrene by gel permeation chromatography. Measurement of radioactivity of tissues following administration of 100 nm and 1 micron I125-labelled polystyrene latex particles for 8 days was corroborative although less secure because of the potential lability of the labelled particles. The extent of absorption of 50 nm particles under the conditions of these experiments was 34% and of the 100 nm particles 26% (as measured by determination of polystyrene content), of which total, about 7% (50 nm) and 4% (100 nm), was in the liver, spleen, blood and bone marrow. Particles larger than 100 nm did not reach the bone marrow, and those larger than 300 nm were absent from blood. No particles were detected in heart or lung tissue.

Effects of progesterone and human chorionic gonadotrophin administration five days postinsemination on plasma and milk concentrations of progesterone and pregnancy rates of normal and repeat breeder dairy cows

Treatment with a progesterone-releasing intravaginal device between days 5 and 12 after estrus elevated (p less than 0.05) plasma progesterone concentrations between days 6 and 8 in comparison with controls. Treatment with injectable progesterone (200 mg) on days 5, 7, 9 and 11 postestrus did not increase plasma progesterone concentrations over controls. The administration of 1500 IU human chorionic gonadotrophin (hCG) on day 5 after estrus resulted in a sustained increase (p less than 0.01) in plasma progesterone concentrations from day 8 until day 20 when measurements ceased. Pregnancy rates, as a result of artificial insemination (AI) at the pretreatment estrus, in these treatments (n = 12-14 each), were unaffected by any of the treatments and ranged from 57.1 to 75.0% at 45-60 days post-AI. In a field trial, of 36 repeat breeder cows treated with 1500 IU hCG 5.5 days after insemination, 47.2% were pregnant at 60 days, whereas 39.5% of saline-treated controls were diagnosed pregnant. Treatment with hCG significantly (p less than 0.05) increased milk progesterone concentrations over controls on days 14 and 20 after insemination.

The structure of the cervical canal of the ewe

The cervical canal of the ewe does not allow for the consistent transcervical passage of insemination instruments. To define the factors affecting transcervical passage, the gross anatomy of the cervix and canal were studied in 100 estrous ewes and then in their reproductive organs following slaughter. In each ewe, the vagina and cervical opening was examined and the external os was classified into one of four types. Insemination instruments were introduced into the cervical opening and manipulation through the canal was attempted. Fluoroscopy was used to record the flow of contrast material through the canal. Ultrasound, xeroradiography and computed axial tomography were used to image the canal of the recovered reproductive tracts. Following imaging, each cervical canal was filled with silicone to create a mold which was used to measure and describe the canal. The average length (+/-SD) of the cervical canal was 6.7 +/- 1.1 cm and contained 4.9 +/- 1.0 funnel-shaped rings (n = 79). Successful passage of insemination instruments was limited by failure to identify the cervical opening and the small openings in the rings, 2.7 +/- 1.1 mm on average (+/-SD) which were not concentrically aligned. The eccentric rings were most consistently the second or third rings from the external os. The design of effective instrumentation and technique for transcervical passage must take these factors into account.

Incorporation of dyes into low density lipoprotein in the presence of non-ionic surfactants

The interaction of low density lipoprotein (LDL) with two model dyes in the presence or absence of non-ionic surfactants has been studied. The water soluble dye, thymol blue, only weakly interacts with LDL to cause slight increases in particle size and the interaction can be reversed on column chromatography and dialysis. The oil-soluble dye sudan III reacts strongly with LDL to produce marked changes in particle size the complex formed being stable to dialysis and gel exclusion chromatography. These interactions are not affected by the presence of surfactants. The results indicate that even small quantities of lipophilic materials will easily partition into the particle, with or without the aid of surfactants and can have a marked effect on the measured size of the particle.

The uptake and translocation of latex nanospheres and microspheres after oral administration to rats

Non-ionic and carboxylated fluorescent polystyrene microspheres (100, 500 nm, 1 and 3 microns in diameter), were fed by gavage (2.5% w/v; 1.25 mg kg-1) daily for 10 days to female Sprague Dawley rats. Peyer's patches, villi, liver, lymph nodes and spleen of animals fed the non-ionic microspheres from 100 nm to 1 micron showed unequivocal evidence of uptake and translocation of the particles. Heart, kidney and lung showed no evidence of the presence of microspheres. Carboxylated microspheres were taken up to a lesser degree than the non-ionised particles. Experiments with 125I radiolabelled 100 nm and 1 micron particles showed a higher uptake of the smaller particles, which were concentrated in GI tissue and liver. Particles were not distributed randomly in the tissues, but were concentrated at the serosal side of the Peyer's patches and could be seen traversing the mesentery lymph vessels towards the lymph nodes. The results demonstrate a need to re-examine the possibilities of particulate oral delivery, as well as the potential toxicity of ingested particulates.

Physiochemical characterization of methotrexate-bovine serum albumin conjugates

Physiochemical parameters have been determined for a series of methotrexate-bovine serum albumin conjugates produced using a water-soluble carbodiimide. Drug coupling produces a heterogeneous product consisting of mixtures of albumin and albumin polymers with varying quantities of covalently bound drug. Due to this heterogeneity, the measurement of absolute physiochemical values was not possible but two factors producing change were evident. The water soluble carbodiimide is responsible for major changes by producing polymers that dominate the properties of the conjugates. The changes induced by the covalently attached drug are less dramatic but still appreciable. The results emphasize that both the attached drug and the method of coupling are significant factors in altering the physiochemical properties of proteinaceous drug carriers.

Characterization of in-vitro drug release and biological activity of methotrexate-bovine serum albumin conjugates

Two series of methotrexate (MTX)-bovine serum albumin (BSA) conjugates have been prepared containing either 96 +/- 16 mg (mean +/- s.d.) or 32 +/- 13 mg of MTX per gram of conjugate. The conjugates released MTX in-vitro in a biphasic manner, the release rate being dependent on the quantity of MTX in the conjugate and on the pH of the release medium. An initial rapid release over 6 h appears to be due to physically adsorbed MTX with the slower secondary release due to covalently bound drug. The conjugates retain a degree of antineoplastic activity in-vitro, but this might be related to the small fraction of MTX that is tightly physically bound.

The effect of the non-ionic surfactant Brij 30 on the cytotoxicity of adriamycin in monolayer, spheroid and clonogenic culture systems

The effects of a non-ionic polyoxyethylated lauryl ether surfactant (Brij 30) on monolayer uptake and spheroid penetration of adriamycin have been studied. Co-incubation of adriamycin with Brij 30 increases intracellular adriamycin levels by 2-3-fold. Although, in the concentrations used, Brij 30 alone is not cytotoxic, adriamycin and Brij 30 mixtures are significantly more cytotoxic (monolayer ID90 = 0.6 microgram/ml; disaggregated spheroid ID50 = 1.9 micrograms/ml) and induce significantly longer spheroid growth delay than adriamycin alone (monolayer ID90 = 2.1 micrograms/ml; disaggregated spheroid ID50 = 3.3 micrograms/ml). Adriamycin is equally cytotoxic to mouse normal granulocytes and chronic myeloid leukaemic (M1 cell line) cells in agar clonogenic cultures. The addition of Brij 30 appears to enhance preferentially the activity of adriamycin against these tumour cells relative to the normal granulocytes.

A low density lipoprotein-methotrexate covalent complex and its activity against L1210 cells in vitro

Low-density lipoprotein particles are potential drug carriers, but only lipophilic drug species partition into the core of the system. In this paper the polar drug methotrexate has been coupled to the exterior protein of low density lipoprotein (LDL) particles using the reagent 1-ethyl-3(3'-dimethylaminopropyl) carbodiimide HCl. The coupled system was sized by photon correlation spectroscopy and the in vitro activity of the complex determined against L1210 cells maintained in medium supplemented with fetal calf serum. The reaction between methotrexate and low density lipoprotein is variable but quantifiable, about ten drug molecules being attached to each LDL particle, resulting in an increase in the radius and polydispersity of the particles. The activity of the complex against L1210 murine leukaemia cells has been demonstrated in vitro, but it is 30 times less active than free drug.