The emerging roles of sphingosine 1-phosphate and SphK1 in cancer resistance: a promising therapeutic target

Cancer chemoresistance is a problematic dilemma that significantly restrains numerous cancer management protocols. It can promote cancer recurrence, spreading of cancer, and finally, mortality. Accordingly, enhancing the responsiveness of cancer cells towards chemotherapies could be a vital approach to overcoming cancer chemoresistance. Tumour cells express a high level of sphingosine kinase-1 (SphK1), which acts as a protooncogenic factor and is responsible for the synthesis of sphingosine-1 phosphate (S1P). S1P is released through a Human ATP-binding cassette (ABC) transporter to interact with other phosphosphingolipids components in the interstitial fluid in the tumor microenvironment (TME), provoking communication, progression, invasion, and tumor metastasis. Also, S1P is associated with several impacts, including anti-apoptotic behavior, metastasis, mesenchymal transition (EMT), angiogenesis, and chemotherapy resistance. Recent reports addressed high levels of S1P in several carcinomas, including ovarian, prostate, colorectal, breast, and HCC. Therefore, targeting the S1P/SphK signaling pathway is an emerging therapeutic approach to efficiently attenuate chemoresistance. In this review, we comprehensively discussed S1P functions, metabolism, transport, and signaling. Also, through a bioinformatic framework, we pointed out the alterations of SphK1 gene expression within different cancers with their impact on patient survival, and we demonstrated the protein-protein network of SphK1, elaborating its sparse roles. Furthermore, we made emphasis on different machineries of cancer resistance and the tight link with S1P. We evaluated all publicly available SphK1 inhibitors and their inhibition activity using molecular docking and how SphK1 inhibitors reduce the production of S1P and might reduce chemoresistance, an approach that might be vital in the course of cancer treatment and prognosis.

Assessment of the latest prescribed drug-related problems

OBJECTIVE: Drug-related problems (DRPs) could affect patient care and lead to deleterious manifestations, therefore, this investigation aimed to review the recently published studies concerning DRPs to improve their availability to clinical pharmacists, hoping that this information will be supportive and relevant to their practice settings. MATERIALS AND METHODS: A search of Elsevier, Sage, Springer/Nature, and Wiley online libraries on Egyptian Knowledge Bank (EKB) was limited to the cumulative period from 1/1/2015 to 20/10/2020. The abstracts of 156 articles were critically reviewed and 50 articles were included based on relevance while excluding books. The selected articles reported DRPs and different strategies to reduce them. Moreover, drug-drug interactions (DDIs) in various patient populations were confirmed by many articles. Additionally, potential drug-drug interactions (pDDIs) predisposing factors were reported by others. RESULTS: 24 articles (48%) illustrated DDIs, 5 articles (10%) demonstrated ADRs, 4 articles (8%) showed medication errors (MEs), and 25 articles (50%) revealed efforts to reduce DRPs. The psychiatric population is at the utmost risk of pDDIs. Polypharmacy was the furthest recurrently reported risk factor related to DDIs. Adverse drug events (ADEs) increased healthcare costs. Different strategies to avoid DRPs were published through the stated period. CONCLUSIONS: Our findings can be supportive to healthcare professionals in enhancing their patients' quality of care by reducing the exposure to ADEs.

Physiological and behavioral responses of land molluscs as biomarkers for pollution impact assessment: A review

Environmental pollution caused by human activities is a global public health concern. This review discusses the impact of different types of pollutants such as pesticides, metals, nanoparticles and others on land molluscs. These molluscs are of great interest as good model organisms for studying biomarker responses in ecotoxicological monitoring programs. Several biomarkers are utilized to characterize and quantify the exposure and harmful impacts of various pollutants. In this review, we have identified physiological and behavioral endpoints (feeding, growth, avoidance, mucus secretion, locomotion and reproductive behavior) for the diagnosis of environmental pollution. The present review displays that all types of pollutants can disturb physiological and behavioral endpoints of gastropods, and these impacts depend on the matrix, exposure time and route as well as the type and concentration of the pollutants in the environment. We have also confirmed that terrestrial gastropods particularly snails as sentinel species could be used as potential bioindicator organisms for environmental quality assessment and thus for predicting potential hazards to human health.

Biomarker responses in terrestrial gastropods exposed to pollutants: A comprehensive review

The chemical contamination of terrestrial ecosystems is a great concern as these ecosystems are the target of most of the pollutants derived from anthropogenic activities such as pesticides, heavy metals, nanoparticles, and others. Terrestrial gastropods are considered to be excellent sentinel organisms for biological monitoring of environmental pollution, as they have the ability to accumulate chemicals in their tissues and exhibit a great potential to evaluate the ecological effects of pollutants in terrestrial ecosystems. The use of biomarkers as sensitive parameters to estimate the exposure or resulting effects of chemicals have received considerable attention. The successful biomarker must be applicable in the laboratory and field conditions. Many biomarkers have been examined to understand the adverse effects of pollutants. In this review, we shed light on different types of biomarkers, such as oxidative stress, genotoxicity and immunotoxicity as diagnostic tools for monitoring the impacts of pollution. These biomarkers can provide information about early detection and quantification of these impacts during their initial manifestations and can facilitate the implementation of a rapid preventive and/or restorative responses in the affected ecosystems, as well as single or multiple biomarkers can be integrated into routine monitoring programs.

Use of multiple endpoints to investigate the ecotoxicological effects of abamectin and thiamethoxam on Theba pisana snails

The ecotoxicological effects of dietary exposure to sublethal concentration (1/20 LC₅₀) of abamectin (ABM) and thiamethoxam (TMX) for two weeks exposure and one week recovery on oxidative stress parameters; lipid peroxidation (LPO), reduced glutathione (GSH), catalase (CAT) and glutathione S-transferase (GST), Deoxyribonucleic acid (DNA) damage as well as immunological parameters; cell death, phagocytosis, lysosomal membrane stability (LMS), lectins, superoxide anion (O₂^-) generation, phenoloxidase (PO), peroxidase (POD) and hemocyanin (Hc) of the land snail, Theba pisana were examined. The results showed that both tested compounds significantly increased DNA damage, LPO content, the activity of CAT and GST, cell death, POD activity, Hc level, whereas, significantly declined in phagocytic activity, LMS, lectins level, O2^- generation, PO activity, and GSH content compared to the controls after two week exposure. After one week of recovery, the measured biochemical parameters of treated snails were slightly repaired but their levels were still less than that of the level of untreated animals. Overall, based on acute toxicity endpoints, ABM appeared to be more harmful than TMX against this animal. Indeed, the different patterns of endpoint responses could represent a useful picture to characterise exposure to these pesticides in the land snail, T. pisana. This battery of snail endpoints might be a promising option to biomonitor the health of the terrestrial ecosystem and to offer valuable insights to the pesticides toxicity mechanisms.

Imidacloprid induced alterations in enzyme activities and energy reserves of the land snail, Helix aspersa

The in vivo sublethal toxic effects (0.2 and 0.6 LD50) of topically applied imidacloprid on biochemical biomarkers in the land snail, Helix aspersa was examined. Biochemical perturbations were assessed by measuring the three enzymatic (Acetylcholinesterase, AChE; catalase, CAT and glutathione-S-transferase, GST) activities and three energy reserves (protein, glycogen and lipids) in the snails. Snail samples were taken from each sublethal dose and control groups at 1, 3 and 7 days after treatment. The results revealed that there were overall decrease in AChE activity as well as depletion of lipids and glycogen contents in the imidacloprid-treated snails compared to control groups. The CAT and GST activities of treated snails with the sublethal doses of imidacloprid were significantly higher than those of untreated controls along the three times of exposure. Moreover, an increase in the level of total proteins was observed in animals treated with 0.6 LD50 imidacloprid compared to control groups. The alterations in all tested biochemical perturbations were most pronounced with the 0.6 LD50 than 0.2 LD50. This study suggests that alterations of the enzyme activities and energy reserves in this species that could be useful as biomarkers of imidacloprid exposure in the evaluation of terrestrial impacts of this insecticide.

Pharmacokinetics and cardiovascular effect of etoricoxib in the absence or presence of St. John's Wort in rats

The effect of chronic administration of etoricoxib (EXB), in the absence or presence of St. John's Wort (SJW), on its pharmacokinetic parameters and blood pressure was investigated in rats.Rats were divided into 3 groups, each group received daily different oral treatment for 3 weeks. Rats' blood pressures were monitored initially, after 1 and 3 weeks of treatment, and after 1 week of discontinuing dosing of both drugs. EXB pharmacokinetic parameters in the absence or presence of SJW were calculated after 3 weeks.SJW was significantly affected EXB pharmacokinetic parameters. The steady state peak plasma concentration and terminal half-life were reduced by 32% and 91%, respectively, due to a > 3 fold increase in its apparent clearance which is a concentration and time dependent effect. EXB was significantly increased (P<0.001) Rats' blood pressure while, co-administration of EXB and SJW was not significantly affect (P>0.05) rats' blood pressure as compared to the control.Monitoring blood pressure of patients anticipated taking EXB for extended period should be advised. The co-administration of SJW with EXB should be avoided since SJW would greatly reduce EXB concentrations by inducing its metabolism.

Feeding and growth responses of the snail Theba pisana to dietary metal exposure

The effects of dietary exposure to copper (Cu), lead (Pb), and zinc (Zn) on feeding activities, growth response, and mortality of Theba pisana snails were studied in 5-week feeding tests. Snails were fed on an artificial diet containing the following Cu, Pb, or Zn concentrations: 0, 50, 100, 500, 1000, 5000, 10,000, and 15,000 μg/g dry food. At the end of 5 weeks, the food consumption rate was decreased with increasinges in both metal concentrations and time of exposure. The estimated concentrations of metals that reduces food consumption to 50% (EC₅₀) after 5 weeks were 56, 118, and 18 μg/g dry food for Cu, Pb, and Zn, respectively. All tested metals in the diet were found to inhibit growth of the snails in a dose-dependent manner. The toxic effect on growth of the tested metals could be arranged in the order Cu > Zn > Pb. The cumulative percentage mortality among snails fed a Cu- or Zn-contaminated diet was 73.3% and the respective value for a Pb-contaminated diet was 13.3%. There was a positive correlation between growth coefficient and food consumption for all tested metals.

Oxidative stress biomarkers in the digestive gland of Theba pisana exposed to heavy metals

The in vivo toxic effects of sublethal treatment of 40 and 80% of 48-h LD(50) of topically applied trace metals [copper (Cu), lead (Pb), and zinc (Zn)] on oxidative stress biomarkers in the digestive gland of Theba pisana were examined. Oxidative individual perturbations were assessed by measuring nonenzymatic (glutathione; GSH) and enzymatic (catalase, CAT; glutathione peroxidase, GPx; and glutathione-S-transferase, GST) antioxidants in digestive gland of the snails. Lipid peroxidation (LPO) was also evaluated as a marker of cell damage. The results indicated that the copper ion was the most potent metal against this snail, followed by zinc and lead, for which the corresponding LD(50) values were 37.88, 261.72, and 652.55 microg/snail, respectively. The no-observed effect concentration (NOEC) values for Cu, Zn, and Pb were 10, 50, and 500 microg/snail, respectively, and the corresponding lowest-observed effect concentration (LOEC) values were 50, 100, and 1000 microg/snail. All trace metals resulted in a significant increase in the level of LPO, whereas a significant decline in the content of GSH was observed when compared with untreated controls. Treatment with both sublethal doses of the metals caused significant increase in CAT activity, except in the case of 40% LD(50) Zn and 80% LD(50) Cu, which exhibited no alteration in CAT when compared to control animals. GPx was significantly increased in snails exposed to 40% LD(50) Cu and Pb as well as 80% LD(50) Cu. However, an opposite effect was observed in snails exposed to 80% LD(50) Pb and in either 40 or 80% LD(50) of Zn-intoxicated animals. Treatment with Pb at two sublethal doses significantly increased GST activity, whereas treatment the animal with Cu caused significant inhibition in this enzyme. Snails exposed to 40% LD(50) Zn showed significant enhancement of GST, whereas snails exposed to 80% LD(50) showed significantly reduced GST activity. Biphasic responses were observed for CAT, GPx, and GST activities in snails exposed to Cu, Pb, and Zn, respectively. This study suggests that upregulation of the antioxidant enzyme activities, elevation of LPO, and the reduction in GSH content is related to oxidative stress in this species that could be useful as biomarkers for the evaluation of contaminated terrestrial ecosystems.

Biomarkers of oxidative stress in the land snail, Theba pisana for assessing ecotoxicological effects of urban metal pollution

This study investigates the biomarkers of oxidative stress and heavy metal accumulation for assessing ecotoxicological effects of urban metal pollution in Alexandria city, Egypt. This investigation was performed in the digestive gland of roadside Theba pisana snails obtained from six different sites in the city. Relationships between heavy metal (Zn, Cu, Pb and Cd) concentrations and oxidative stress indicators were also examined. The results showed that mean concentrations of the measured elements (mugg(-1) dry weight) were higher in polluted sites when compared to the background levels of the reference site. The pattern of metals accumulation at all sites was Zn>Cu>Pb>Cd. In the metal polluted sites, snails displayed higher mean of catalase (CAT), glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities, lower reduced glutathione (GSH) content and higher levels of lipid peroxidation (LPO) compared to snails from the reference site. All oxidative stress parameters were positively correlated to heavy metal concentrations except GSH content which exhibits negative correlation with the concentrations of these metals. Our results suggest that the tested antioxidant defenses are sensitive parameters that could be useful as oxidative stress biomarkers in snails exposed to the actual metals in the environment. These biomarkers when complemented with metal accumulation in the digestive gland of snails may provide a powerful biomonitor for the assessment of environmental metal pollution.

In vivo evaluation of oxidative stress biomarkers in the land snail, Theba pisana exposed to copper-based pesticides

The in vivo evaluation of oxidative stress biomarkers in the digestive gland of Theba pisana exposed to sublethal doses (40% and 80% of LD(50) after 48 h) of copper-based pesticides; copper oxychloride, copper hydroxide and copper sulphate was examined. Oxidative individual perturbations were assessed by measuring non-enzymatic (glutathione; GSH) and enzymatic (catalase; CAT, glutathione peroxidase; GPx and glutathione S-transferase; GST) antioxidants in digestive gland of the snails. Lipid peroxidation (LPO) was also evaluated as marker of cell damage. The results indicated that copper sulphate was the most potent compound against this snail followed by copper hydroxide and copper oxychloride where their corresponding LD(50) values were 26.54, 334.54 and 582.18 microg snail(-1), respectively. Copper-based compounds resulted in a significant increase in the level of LPO whereas a significant decline of GSH content in the digestive gland of snails was observed when compared with untreated controls. The CAT, GPx and GST activities of treated snails were significantly higher than those of untreated controls. In general, the activation power of these compounds was in the following order: copper sulphate > copper hydroxide > copper oxychloride. This study suggests that up-regulation of the antioxidant enzyme activities, elevation of LPO and the reduction of GSH content is related to oxidative stress in this species that they could be used as potential biomarkers of copper-based pesticides exposure.

Potential of some monoterpenoids and their new N-methyl carbamate derivatives against Schistosomiasis snail vector, Biomphalaria alexandrina

Some monoterpenoids and their corresponding new N-methyl carbamate derivatives were used to study their molluscicidal effect on Biomphalaria alexandrina, the snail-vector of Schistosoma mansoni in Egypt. Improving the efficacy of the tested monoterpenoids and/or their corresponding carbamates by either piperonyl butoxide (PBO) or triton X-100 (TX) was also performed. Thymol, β-citronellol, carvacrol, and geraniol exhibited high molluscicidal activity against the snails. Geraniol, β-citronellol, and carvacrol were strongly synergized by PBO but, an opposite trend was found with TX. The molluscicidal activity of geraniol or β-citronellol when mixed with PBO was as potent as copper sulfate. Another attempt to improve the bioactivity of monoterpenoids was through their structure modifications. Thus, conversion of the tested monoterpenoids into their corresponding carbamates led to enhancement in the activity of aliphatic monoterpenoids and reduction in the aromatics.

The effects of induced diabetes and cutaneous Leishmania infection on the pharmacokinetics of antimony in hamsters

Patients with certain diseases appear to be at greater risk of developing adverse drug interactions, either because of the disease state itself or the drugs used to treat it. The effects of streptozotocin-induced diabetes and/or cutaneous Leishmania major infection on the pharmacokinetics of antimony (SbV) have now been investigated, in hamsters treated with sodium stibogluconate (Pentostam). The animals were randomly divided into five groups, each of 20 hamsters, known as D (for diabetes without leishmaniasis), DL (diabetes induced prior to the leishmaniasis), L (leishmaniasis without diabetes), LD (diabetes induced after leishmanial infection) and C (the control group, of animals with neither diabetes nor leishmaniasis). After its diabetes and/or leishmaniasis (if any) was established, each animal was given an intramuscular dose of sodium stibogluconate (80 mg/kg) each day for 3 weeks. Blood samples were collected after the first or last doses, to allow the pharmacokinetic parameters of SbV after single and multiple dosing to be compared. Although the between-dose interval (24 h) was more than 10 times longer than the terminal elimination rate constant (t1/2) at steady state, there was a significant increase in the mean peak SbV concentration (Cmax), as the result of multiple dosing, in all five groups (P<0.001 for each). The hamsters with diabetes showed the least accumulation of SbV in their blood, whether or not they were infected with L. major. In the non-diabetic animals of groups L and C, the apparent total clearance of SbV (CL/F) was decreased by multiple dosing, being, respectively, 34.5% and 23.0% lower after the 21st dose than after the first. An increase in urine volume was the reason for the significant increase in CL/F in group D (P<0.001), and this offset the decrease in CL/F seen in the L group, resulting in no change in CL/F in the animals of the DL group. Three weeks of antileishmanial treatment produced no significant reductions in the leishmanial lesions on the parasite-inoculated foot-pads of the hamsters in the L or DL groups but such reductions were detected in the animals of the LD group (P<0.001). In conclusion, it appears that the administration of SbV over a few weeks may cause renal toxicity and, in clinical use, should therefore be accompanied by the regular monitoring of renal function. A cautious increase in SbV dosing may be necessary for the effective treatment of L. major (and perhaps other species of Leishmania) in diabetic patients.

Soil amendment with dried weed leaves as non-chemical approach for the management of Meloidogyne incognita infecting tomato

In pot trial, dried ground weed leaves of Cynodon dactylon, Datura stramonium, Eichhomia crassipes, Emex spinosus, Ricinus communis and Sisymbrium irio were mixed with soil at the rate of 1, 3, 5 and 10 g/kg soil and compared their nematicidal potential with carbofuran as a standard against the root-knot nematode, M. incognita infecting tomato. In addition, their effects on growth rate of tomato plants were also investigated. The results showed that M. incognita populations in the soil and root galling were significantly suppressed when the dried leaves of the tested weeds at all rates were allowed to decompose in the soil. All amendments exhibited varying degree of reduction compared to control. The highest reduction was noticeable with the plants grown in Sisymbrium irio amended soil followed by Datura stramonium and Emex spinosus. In addition, employing high rate of the tested weeds gave higher activity in suppressing the nematode both in the soil and in tomato roots than using low rate. The data also indicated that all amendments at low rates significantly increased growth indices of tomato over control treatment, except Cynodon dactylon and Emex spinosus which decreased it, particularly in the shoot system. On the other hand, their high rates showed phytotoxic effects. These weed species may offer considerable promise as soil amendments for control of root-knot nematode, M. incognita.

Residual behaviour of profenofos on some field-grown vegetables and its removal using various washing solutions and household processing

Profenofos (Selecron 72% EC), was sprayed on field-grown pepper and eggplant at the recommended rate of 1.28 kg a,i/ha. Fruit samples were collected at 1 h to 14 days after application and analysed to determine the content and dissipation rate of profenofos. The effect of different washing solutions and some household processing on the removal of such residues from treated vegetables were also investigated. Profenofos residues were quantified by using gas chromatography. The results showed that the consumable safety time were found to be 10 days on sweet pepper and 14 days on hot pepper and eggplant fruits. The initial disappearance of profenofos appeared to follow first order kinetics with different rates of reaction of 0.38, 0.40 and 0.35 day(-1) for hot pepper, sweet pepper and eggplant, respectively. The corresponding half-lives (t1/2) were 1.84, 1.74 and 1.96 days. Also, the results indicated that tap water, potassium permenganate and acetic acid solution gave high percent removal of profenofos residues from hot and sweet pepper fruits, while no detectable residues was found in eggplant fruit after washing with soap and acetic acid solutions. In general, all tested washing solutions gave higher percent removal of profenofos residues from eggplant fruit than the two other pepper fruits. Blanching and frying of pepper and eggplant fruits resulted in great reduction to almost completely removed (approximately 100%) of the deposited profenofos. In addition, pickling process removed 92.58 and 95.61% from hot pepper fruit after one week and after two weeks, respectively.

Enhancement of absorption of insulin-loaded polyisobutylcyanoacrylate nanospheres by sodium cholate after oral and subcutaneous administration in diabetic rats

Polyisobutylcyanoacrylate (PIBCA) nanospheres were employed as biodegradable polymeric carriers for oral (p.o.) and subcutaneous (s.c.) delivery of insulin. The polymerization technique used was able to hold 65%-95% of insulin added 30 min after initiation of polymerization. The percentage drug loading was monomer concentration dependent. Insulin adsorption to the nanospheres was measured by radioimmunoassay. Although Pluronic F68 (0.5%) did not significantly alter the in vitro insulin degradation half-life T50%, sodium cholate (0.5%) increased the degradation T50% of insulin by 56% (from 13.6 +/- 1.6 to 22.1 +/- 2 min). This study also investigated the in vivo performance of insulin-loaded PIBCA in aqueous suspension with or without sodium cholate (0.5%) and Pluronic F68 (0.5%) surfactants after oral and subcutaneous administration to alloxan-induced diabetic rats. Insulin absorption was evaluated by its hypoglycemic effect. Insulin associated with PIBCA nanospheres retains its biological activity up to 15 h and 24 h after oral and subcutaneous administrations, respectively. Administered orally insulin-loaded (75 U/kg) nanospheres, in the presence of surfactants, significantly reduced the mean blood glucose level from 392 +/- 32 to 80 +/- 13 mg/dl within 2 h and maintained it at 100 mg/dl or less for more than 8 h. On the other hand, the subcutaneous administration of insulin-loaded (25 U/kg) nanospheres significantly decreased the blood glucose level from 406 +/- 33 to 88.5 +/- 12.8 mg/dl within 1 h, and the lowered glucose level was maintained at 100 mg/dl or less for more than 12 h; it returned to its initial value 24 h after administration. Insulin-loaded nanospheres with surfactants showed significant (P < .05) pharmacological availability (PA%) of 37.6% +/- 3.7% and 65.2% +/- 2.7% after oral and subcutaneous dosages, respectively. The existence of surfactants with PIBCA nanospheres improved the oral PA% by 49.2%. These findings suggest that the developed PIBCA, in the presence of surfactants, would be useful not only in improving insulin gastrointestinal absorption, but also in sustaining its systemic action by lowering the blood glucose to an acceptable level.

Synthesis and molluscicidal structure-activity relationships of some novel 1,2,4-triazole N-methyl carbamates

A new series of 1,2,4-triazole derivatives and their corresponding carbamates have been synthesized and screened for their molluscicidal activity against two types of terrestrial snail, Helix aspersa and Theba pisana, by two methods of application, either as contact or as bran baits. Several of the tested compounds exhibited good molluscicidal activity, and T pisana was more sensitive than H aspersa. Substitution at the o- and/or p-positions of the phenyl ring with chlorine or bromine gave higher molluscicidal activity than the unsubstituted compound, with o,p-dichloro substitution being optimum. In addition, compounds containing two triazole moieties showed higher molluscicidal activity, particularly as stomach poisons, than the contact toxic effect of the corresponding compound with one triazole ring. In general, carbamate derivatives were more active than their corresponding 1,2,4-triazole derivatives.

Preparation and in vivo evaluation of parenteral metoclopramide-loaded poly(alkylcyanoacrylate) nanospheres in rats

Metoclopramide-loaded poly(alkylcyanoacrylate) (PACA) nanospheres were prepared by emulsifier-free polymerization in aqueous media at ambient conditions. The optimum polymerization conditions for metoclopramide sorption on PACA nanospheres in the presence of dextran (DEX) or hydroxypropyl-beta-cyclodextran (HPCD) in the polymerization medium were studied and the feasibility of either poly(isobutylcyanoacrylate) (PIBCA) or poly(ethylcyanoacrylate) (PECA) nanospheres as parenteral prolonged release drug delivery system of metaclopramide in rats was also investigated. The optimum time for the addition of metaclopramide after initiating the polymerization was 1 h, which results in 14.8 +/- 0.4 and 9.2 +/- 0.5% of drug loading for PIBCA and PECA, respectively. The HPCD in the polymerization medium of PECA nanospheres improved the drug adsorption compared to DEX at all times, but the difference was only significant (p < 0.05) when metoclopramide was added at 0 and 30 min. Wistar rats were given subcutaneous (s.c.) injections of metoclopramide solution (5 mg/kg) and three different metoclopramide nanospheres suspensions (10 mg/kg) on two phases. The drug solution is rapidly absorbed, distributed, and eliminated. The maximum drug concentration was observed after 30 min of s.c. administration of all the tested nanosphere formulations. PECA-HPCD showed the highest concentration (3.16 +/- 0.66 mg/L) followed by PIBCA-DEX (1.95 +/- 0.37 mg/L) and PECA-DEX (1.68 +/- 0.28 mg/L). The AUCs of PECA-DEX, PECA-HPCD and PIBCA-DEX were 4.8, 1.88 and 2.43 times higher than that of the solution form, respectively. Following PECA-DEX the maximum drug concentration, 1.68 +/- 0.28 mg/L, rapidly decreased to 0.54 +/- 0.05 mg/L. The drug was successfully maintained around this serum drug concentration up to 12 h in rats and the mean drug concentration was reduced to 0.2 +/- 0.02 mg/L, 63% reduction, after 24 h of nanosphere administration. The developed aqueous parenteral prolonged release preparation (PECA-DEX) could be used as a promising intermittent formula for metoclopramide or other drugs when the oral route is not accessible, especially during managing chronic nausea in patients with advanced cancer.

The effect of absorption enhancers on the initial degradation kinetics of insulin by alpha-chymotrypsin

The goal of this investigation was to establish a fast method to screen various insulin absorption enhancers by following their effect on the initial kinetics of insulin incubated with alpha-chymotrypsin at 37 degrees C. A simple, sensitive and reproducible reversed phase high performance liquid chromatography (HPLC) method has been developed to carry out this goal. Linear responses (r > 0.999) were observed over the range of 0.4-4 U/ml for insulin. There was no significant difference (P < 0.05) between inter- and intra-day studies for insulin. The mean relative standard deviations (RSD%) of the results of within-day precision and accuracy of insulin were 12%. The assay was sensitive to detect the existence of any metabolite due to the addition of any absorption enhancers, even if it was not seen with insulin alone. Three metabolites (A-C) were detected only when insulin was incubated with alpha-chymotrypsin at 37 degrees C. Metabolite D was observed when either glycocholic acid (0.5, 1%) or taurochenodeoxycholate (0.5, 1%) was incubated with insulin in the absence of alpha-chymotrypsin at 37 degrees C. The compounds that significantly increased insulin T50% were glycyrrhizic acid (0.5%) > deoxycholic acid (1%) > deoxycholic acid (0.5%) > glycyrrhizic acid (1%) > cholic acid (0.5, 1%). Capric acid (0.5%), hydroxypropyl-alpha-cyclodextrin (0.5, 1%) and dimethyl-alpha-cyclodextrin (0.5, 1, 5%) did not significantly affect insulin T50%. The bile salts increased insulin T50% in this order: deoxycholate > cholate > glycocholate > taurocholate > taurodeoxycholate > taurochenodeoxycholate > glycodeoxycholate. The results obtained would support the feasibility of utilizing such method for screening any compound incorporated in insulin formulation. These compounds should be used in the minimum possible concentration to avoid or minimize insulin degradation.

Sustained release microspheres of metoclopramide using poly(D,L-lactide-co-glycolide) copolymers

Metoclopramide was encapsulated with poly(D,L-lactide co glycolide) copolymers of different molecular weights using the emulsification/solvent evaporation technique. These polymers included poly(D,L-lactide-co-glycolide) 50:50 with inherent viscosity (i.v.) 0.2, and average molecular weight 8000, poly(D,L-lactide-co-glycolide) 50:50 with i.v. 0.8 and average molecular weight 98000 and poly(D,L-lactide-co-glycolide) 85:15 with i.v. 1.4 and average molecular weight 220000. The effect of the polymers' molecular weights as well as the polymer-to-drug ratios on the yield, the particle size distribution, and the drug content of the microspheres was investigated. The release rate of the drug was studied for 96 h in a phosphate buffer of pH 7.4. The study also investigated the effect of the new poly(lactide-co-glycolide)-H series on the characteristics of the prepared microspheres. Data revealed that a higher yield was obtained with polymers of lower molecular weights. A lower yield was also obtained with increasing the drug-to-polymer ratios for all the investigated polymers. The drug content of the microspheres was lower than expected, ranging from 49-85%, which suggested a chemical interaction between the drug and the polymers, as proved by differential scanning calorimetry (DSC) and infra red (IR) studies. A higher interaction was obtained with the H-series of the copolymers. The release of the drug mainly followed zero order kinetics on increasing either the polymers' molecular weights or the polymer-to-drug ratios. Diffusion kinetics was observed only with those batches prepared with low polymer-to-drug ratios. The release rate was a function of both the polymers' molecular weights and the drug-to-polymer ratios.

Zidovudine, diclofenac and ketoprofen pharmacokinetic interactions in rats

Zidovudine (AZT) is widely used for the management of human immunodeficiency virus (HIV) infections. Non-steroidal anti-inflammatory drugs (NSAIDs) are often used for relief of non-specific fever and musculoskeletal pain in patients with HIV including those with AZT-induced myopathy. The effects of single oral doses of diclofenac and ketoprofen on AZT pharmacokinetics were studied in rats. The influence of AZT on the pharmacokinetics of diclofenac or ketoprofen was also investigated. The administration of diclofenac (3 mgkg(-1)) or ketoprofen (1 mgkg(-1)) did not significantly alter AZT (1.5 mgkg(-1)) pharmacokinetic parameters compared with administering AZT alone. There was no significant difference between the pharmacokinetics of ketoprofen given alone or in combination with AZT. However, the co-administration of AZT with diclofenac affected the pharmacokinetics of diclofenac. The Cmax of diclofenac was significantly (P < 0.05) increased by approximately threefold within a shorter time (0.6+/-0.2 h). The mean AUC value for diclofenac was increased from 2.29 to 5.04 microg mL(-1) h in the presence of AZT. AZT decreased the mean apparent clearance of diclofenac by 54%. The increase in diclofenac concentrations could be attributed to a decrease in its clearance or delay in its metabolite formation due to a competitive effect. The results show that diclofenac and AZT should be given with caution because of the possible increase of diclofenac toxicity, in anticipation of follow-up clinical studies to examine this finding in man. AZT and ketoprofen could be a safe combination since no pharmacokinetic interaction was detected.

In vivo performance of parenteral theophylline-loaded polyisobutylcyanoacrylate nanoparticles in rats

Theophylline-loaded polyisobutylcyanoacrylate (PICA) nanoparticles were prepared by emulsifier-free polymerization in aqueous media at ambient conditions. PICA nanoparticles were shown (in vitro) to be a promising controlled delivery system for theophylline. Therefore, this study was conducted to investigate the feasibility of PICA nanoparticles as a parenteral controlled drug delivery system in rats. Wistar rats were given intraperitoneal (i.p.) injections of theophylline solution (4 mg/kg) and theophylline nanospheres suspension (8 mg/kg) on two different occasions. Theophylline serum concentrations were measured by an HPLC assay. The drug solution was rapidly absorbed, distributed, and eliminated. The peak concentration (Cmax), 5.34+/-1.9 mg/l, was achieved 20 min following administration. The mean residence time was 2.94 h, and the apparent clearance was 0.31 (l/h)/kg. After nanospheres administration the mean Cmax, 2.53+/-1.1 mg/l, was attained at 3 h. The drug was successfully maintained around this elevated serum drug concentration up to 11 h in rats. The drug concentration was only reduced to 1.43+/-0.98 mg/l (i.e. reduced by 43.5%) after 20 h of administration. This present study provides evidence that the sorption of theophylline to PICA nanoparticles could control the drug release in rats.

Cassava root meal in diets for growing rabbits

The effects of substituting imported cassava root meal for barley meal in rations for growing rabbits were examined. Four diets were used. Diet 1 contained 500 g/kg barley meal, the remainder of the diet consisted of soya bean meal, barley straw, vitamins and minerals. Diets 2, 3 and 4 contained increasing amounts of cassava root meal in place of barley meal at 165, 335 and 500 g/kg respectively with L-lysine and DL methionine supplements. A growth trial was carried out using 48 individually caged rabbits from 0.8 kg to 2.0 kg and the digestibilities of the diets were determined in balance trials. Growth rates were similar on all treatments (41.6, 43.1, 40.6 and 41.0 g/d respectively, s.e.d. 2.39), as were dry matter food conversion ratios (2.27:1 overall). The cassava meal appeared to have a digestible energy approximately 1.6 MJ/kg DM higher than that of the barley meal. There appeared to be no adverse effects of feeding diets containing 500 g/kg cassava root meal on animal health. The intrinsic variability in chemical composition of cassava root products is discussed.

Incorporation of grass silage, whole cereal grains, cassava and cottonseed meal into diets of rabbits kept in a simulated tropical environment

The growth and feed conversion of rabbits fed either grass silage or whole grains and supplementary pelleted concentrate of cassava/cottonseed diets were investigated. Poor quality grass silage (pH 4.9) was almost completely rejected by young rabbits initially fed either 17.8 g or 35.5 g DM/day of a supplementary concentrate. Rabbits on the lower level of concentrate provision lost 0.35 g liveweight per day. Rabbits initially weighing 1.77 kg fed complete pelleted diets containing 667 g/kg maize or 667 g/kg sorghum showed improved daily liveweight gains (22.6 g) over rabbits fed whole grains and pelleted supplements (19.4 g) in an experiment lasting 40 days. In a second experiment there were no significant effects of pelleting or type of cereal on liveweight gain or feed conversion ratio. Pelleting significantly improved crude protein digestibility of diets whilst maize diets were superior in DM, organic matter and crude protein digestibilities. The inclusion of cottonseed meal containing 700 mg/kg free gossypol in diets at levels of 150 and 300 g/kg did not affect growth rate or feed conversion in rabbits weighing 0.92 kg initially. These diets contained up to 364 g/kg cassava suggesting that this ingredient can be used in rabbit diets as an energy source in replacement for whole grains.