A brief report on some physiological parameters of streptozocin-diabetic rat.

Several biological changes occur when streptozocin is given to experimental animals. The rat streptozocin (STZ) model is extensively used in diabetic experiments. In this brief report, the main physiological characteristics of rats injected with streptozocin are presented. These characteristics are manifested by weight loss, organ weight reduction, serum glucose elevation, decrease in serum insulin level, and other enzyme and hormonal changes. A collection of these parameters may be helpful in establishing a database to describe this model.

Pharmaceutical profile of vitamin C tablets and capsules.

This study examines the pharmaceutical profile of 3 brands of immediate-release vitamin C tablets (500 mg) available commercially in North Carolina and 3 batches of vitamin C capsules (500 mg) extemporaneously prepared in our laboratory. Several pharmaceutical tests were performed on 3 bottles from 3 different brands of immediate-release vitamin C tablets that were purchased from local stores. The brands were compared with respect to thickness, weight variation, hardness, dissolution, disintegration time, and content uniformity tests. The results showed differences among the brands in thickness, weight variation, hardness, and disintegration time. Bottles from 2 of the brands showed a significant difference in some of their test profiles. Weight variation, dissolution, and content uniformity were determiined for the prepared capsules. The average weight of the capsules from the 3 batches was similar and was slightly below 700 mg. The content of ascorbic acid in the capsules ranged form 95.4% to 113.5% of the labeled amount, with an overall average of 107.5% for the 3 batches. Dissolution tests on the capsules revealed that the release of vitamin C was complete within a 1-hour period, which is similar to that seen with the commercial tablets. These results make it advisable for pharmacists, when counseling patients, to have this variability among commercial brands of vitamin C in mind.

Experimenting with a new emulsifying agent (tahini) in mineral oil emulsion.

The use of tahini, a sesame paste, as an emulsifying agent was the subject of this investigation. Mineral oil emulsion, USP was used as an emulsion model. Tahini partially or completely replaced acacia in the oficial emulsion. The rate of creaming (expressed as percent) and the viscosity of the resulting emulsions were measured. Also, emulsions were prepared containing tahini only. The results show that tahini-prepared emulsions had lower creaming rates and viscosity after one month of storage at room temperature. Thus, a better physical stability was achieved when tahini was used as and emulsifying agent.

In vitro studies on the release of morphine sulfate from compounded slow-release morphine-sulfate capsules.

Morphine sulfate is a commonly prescribed drug for the relief of pain. This study investigated the dissolution profile of extemporaneously prepared slow-release morphine-sulfate capsules and MS Contin (Purdue Frederick, Norwalk, CT). Extemporaneously prepared capsules obtained from one pharmacist were compared with MS Contin tablets. In addition, we compared capsules prepared by 15 different pharmacists and three different batches prepared by the same phaarmacist. A dissolution test was used to generate the dissolution profile for drug products. The compounded capsules demonstrated a slow-release profile that was similar to the commercial preparation except that the morphine sulfate was released at a faster rate. The zero-order dissolution rate constant (k0, milligrams/hour) was calculated from the dissolution profiles. Statistical analysis of k0 showed that caapsules prepared extemporaneously by pharmacist one showed a faster dissolution compared to MS Contin (p=0.0368); the difference was a rate of 0.81 mg/hour during the first four hours. When variability among compounding pharmacists was compared, only one batch of compounded capsules prepared from 15 different pharmacies showed a significantly different rate of morphine release. When reproducibility by a single pharmacist was examined, capsules showed some variation from batch to batch (p=0.05). Although variation was seen from one pharmacy to another and even between different batches made by the same pharmacist, the compounded capsules showed a remarkably consistent in vitro slow-release profile.

Calamine lotion: experimenting with a new suspending agent.

The use of a new suspending agent is investigated. Calamine lotion, USP contains bentonite magma as a suspending agent. In this study, bentonite magma was partially or completely replaced with a new suspending agent called tahini. Tahini is sesame paste composed of crushed sesame seeds in sesame oil. It is frequently used in middle eastern food as a thickening and suspending agent. Calamine lotion was prepared, generally, according to the USP method. The formula contained 40% v/v magma. Tahini was added instead of bentonite magma by replacing 100%, 99%, 90%, 75%, 50% and 25% of the magma. The sedimentation volume and the degree of flocculation were calculated for the resulting preparations. Rheological characteristics of bentonite- and tahini-containing lotions were also determined. Sedimentation volume showed 0.723 and 0.851 (p=0.05) for the lotions containing 100% bentonite and 100% tahini, respectively. The degree of flocculation was 2.00 and 2.35 (p=0.05) for the 100% bentonite and 100% tahini lotions, respectively. The rheograms of all the suspensions showed pseudoplastic flow. Overall, the use of tahini in calamine lotion has improved the physical stability of the formula.

Erythrocytes as oral delivery systems for human insulin.

The use of different forms of human red blood cells as oral carrier systems for human insulin in vivo was the subject of this investigation. Male Wistar rats were made diabetic by a single intraperitoneal injection of streptozocin (100 mg/kg). Three days after the injection, rats were found diabetic as evidenced by elevated fasted blood glucose concentration (200 mg/dl or higher). Rats received orally one of the following (100 U, 2 ml): an insulin solution, a ghosts-insulin suspension, a vesicles-insulin suspension, a liposomes-ghosts-insulin suspension, or a liposomes-vesicles-insulin suspension. Free carrier suspensions or sodium chloride solution (0.9%) were also given orally as controls. Blood glucose concentration was determined just before administration and at 1, 2, 3, 4, 5, 6, and 7 hr post administration. The results show that all treatment groups, except liposomes-ghosts-insulin, were significantly different statistically from their respective controls (i.e., the free carriers).

A possible nonspecific site of action of amiodarone on newborn rat heart cell in culture.

Amiodarone and its major metabolite desethylamiodarone are potent antiarrhythmic drugs that have multiple pharmacological effects on the heart. We examined the effect of both drugs on the neonatal rat heart monolayer cell culture. The cells were stimulated with L-arterenol (10(-7) M) and choleratoxin (1.5 micrograms/ml). Both the spontaneous pulsation rate and intracellular cAMP level were followed. Amiodarone (10(-7) M) or desethylamiodarone (10(-7) M), incorporated into phosphatidylcholine vesicles, decreased the stimulated cell pulsation rate 3 min after addition of drugs, and the level of intracellular cAMP 30 min after addition as well. Propranolol (10(-7) M) had no further effect on the pulsation rate after 3 min. In the presence of amiodarone and propranolol the stimulation of L-arterenol was completely abolished and both the pulsation rate and cAMP level proved to be lower than the control values. The stimulation of choleratoxin on pulsation rate was also decreased by addition of amiodarone and the cAMP level was lowered after 30 min as well. Desethylamiodarone exhibited similar behavior to amiodarone although it proved to be less effective. It is unlikely that amiodarone and desethylamiodarone act on beta-adrenergic receptors in a competitive manner. Our data suggests that amiodarone and its metabolite could act in a nonspecific manner perturbing the hydrophobic interaction in the cell membrane and thereby decoupling the receptor or the nucleotide regulator protein and adenylate cyclase.

Buccal administration of human insulin in streptozocin-diabetic rats.

This study investigates the use of the buccal route of administration in the delivery of human insulin in rats. Streptozocin-induced diabetic female Wistar rats were used in this study. Insulin (100 U) either free (i.e., insulin solution) or associated with a carrier, namely erythrocyte-ghosts (EG) and liposomes-vesicles (LEV), was administered buccally. Blood samples were collected from the tail over a period of 5 hr. These results indicate that insulin absorption occurred, as evidenced from a decrease in blood glucose concentration, and in the case of free insulin and erythrocyte-ghosts-insulin (EG-INS). The magnitude of the blood glucose level decline was at its maximum of 39.53 mg/dl (at 2 hr) and 26.23 mg/dl (at 4 hr) for free insulin and EG-INS, respectively. No significant difference in the blood glucose level profile was observed after either LEV or liposomes-vesicles-insulin (LEV-INS). This study demonstrates the ability of human insulin to be absorbed from the mouth cavity when it is instilled in the form of a simple solution or EG-INS suspension. This absorption resulted in a definite pharmacological effect but not a significant therapeutic effect.

The interaction of cisplatin plus etoposide with radiation +/- hyperthermia.

The addition of concurrent etoposide and cisplatin to radiation +/- hyperthermia was evaluated in the murine FSaIIC fibrosarcoma tumor system. Tumor growth delay (TGD) demonstrated that when the drugs were tested with radiation (3 Gy daily X 5) plus (43 degrees X 30 min) local hyperthermia, cisplatin/hyperthermia/radiation (TGD approximately 25 days) was significantly more effective than etoposide/hyperthermia/radiation (TGD approximately 14 days). The addition of etoposide to cisplatin/hyperthermia/radiation, however, yielded a significantly longer growth delay (approximately 34 days). Tumor cell survival studies demonstrated that hyperthermia (43 degrees C, 30 minutes) was dose modifying for etoposide cytotoxicity (dose modifying factor approximately 2.0 as determined by comparisons of the slopes of the curves). The addition of etoposide to cisplatin modified cisplatin killing only slightly at 37 degrees C or 43 degrees C. Considerable additional cell kill was observed over a range of radiation doses with cisplatin, hyperthermia, and etoposide added singly or in combination, especially at the lowest radiation dose tested (5 Gy), but essentially no dose modification was observed. Evaluation of Hoechst 33342 dye-selected tumor subpopulations demonstrated that cisplatin, etoposide, radiation (10 Gy), etoposide plus radiation, and cisplatin plus radiation killed significantly fewer dim (presumably hypoxic) cells than bright (presumably normally oxygenated) cells. Hyperthermia killed more dim than bright cells. The combination of hyperthermia with cisplatin and radiation, however, resulted in approximately 5-fold lesser kill in dim cells, and the addition of etoposide increased this differential to 6.4-fold. These results indicate that etoposide adds small but measurable antitumor effects when used with cisplatin alone or with cisplatin in combination with radiation +/- hyperthermia (especially at lower radiation fraction sizes).

Classification of antineoplastic treatments by their differential toxicity toward putative oxygenated and hypoxic tumor subpopulations in vivo in the FSaIIC murine fibrosarcoma.

In order to investigate the effect of environmentally determined conditions on the cytotoxicity of anticancer treatments, Hoechst 33342 dye selected tumor subpopulations were separated after in vivo treatment and plated for single cell colony survival. The 10% brightest cells were assayed as putative normally oxygenated cells and the 20% dimmest as putative hypoxic cells. At single therapeutic doses, cyclophosphamide treatment resulted in the largest differential killing between bright and dim cells (6.3-fold bright greater than dim); 1,3-bis(2-chloroethyl)-1-nitrosourea was 3.2-fold more cytotoxic toward bright cells and carboplatin was 2.4-fold more toxic toward bright cells. Both radiation (10 Gy) and melphalan were 2.2-fold more toxic to bright cells, while cis-diamminedichloroplatinum(II) was 1.8-fold, thiotepa was 1.2-fold and procarbazine was 1.3-fold more toxic to bright cells. Actinomycin D was 3.4-fold more toxic to bright cells. Adriamycin was 2.2-fold, vincristine was 2.1-fold, and etoposide was 1.6-fold more toxic to bright cells. Bleomycin and 5-fluorouracil were also tested and were 1.5- and 2.3-fold more toxic to bright cells, respectively. Only four treatments were more toxic to dim cells: mitomycin C (3.5-fold), misonidazole (1.5-fold), etanidazole (3.5-fold), and 43 degrees C, 30 min local hyperthermia (2.6-fold). In an attempt to shift the pattern of dim cell sparing, Fluosol-DA plus carbogen (95% O2/5% CO2) breathing was added to treatment with radiation (10 Gy), melphalan, cis-diamminedichloroplatinum(II), and etoposide. Although each of these treatments became significantly more toxic with the addition of Fluosol-DA/carbogen, only with melphalan did the combination overcome the sparing of dim cells. These results indicate that cells located distally from the tumor vasculature are significantly less affected by most anticancer drugs and suggest that successful therapeutic strategies against solid tumors will involve greater use of the few treatments which are more toxic toward this tumor subpopulation.

Cross-resistance and glutathione-S-transferase-pi levels among four human melanoma cell lines selected for alkylating agent resistance.

A panel of four cell sublines, each selected for resistance to a different antineoplastic agent, has been developed from a human malignant melanoma cell line G3361. Following repeated exposure to escalating doses of the drug of interest, cloned sublines were developed that are 9-fold resistant to cisplatin (G3361/CP), 11-fold resistant to 4-hydroxyperoxy-cyclophosphamide (4-HC) (G3361/HC), 4-fold resistant to carmustine (BCNU) (G3361/BCNU), and 4-fold resistant to melphalan (G3361/PAM). The cross-resistance of each resistant cell line was determined for cisplatin, BCNU, 4-HC, melphalan, carboplatin, nitrogen mustard, and Adriamycin. In general, the alkylating agent-resistant cell lines were specifically resistant to the drug used for selection with the exception of the G3361/CP line, which was greater than 10-fold resistant to the cisplatin analogue carboplatin, 4-fold resistant to 4-HC, and slightly (1.5-fold) resistant to melphalan, and the G3361/BCNU line, which was slightly (1.8-fold) resistant to melphalan. Collateral sensitivity of the G3361/CP, G3361/PAM, and G3361/4HC lines to killing by BCNU was also observed. Glutathione-S-transferase activity was elevated in each of the alkylating agent-resistant cell lines by 3- to 5-fold with chlorodinitrobenzene substrate. On Western blotting, the glutathione-S-transferase-pi (GST-pi) isoenzyme protein was elevated in the resistant cells by 3- to 5-fold. A complementary DNA (pTS4-10) coding for GST-pi has been cloned from a lambda gt11 library, sequenced, and used as a probe to determine the relative levels of GST-pi mRNA in the alkylating agent-resistant cell lines. GST-pi mRNA levels were elevated (8- to 15-fold) in the resistant cell lines, indicating that the GST-pi increases were mediated through an increase in mRNA levels. GST-pi elevations are a frequent event in cells selected for alkylating agent resistance, and in some cases, of multiple drug resistance. However, the lack of cross-resistance among cell lines selected for resistance to different alkylating agents, all of which have elevated GST-pi levels, indicates that increased levels of GST-pi cannot be the predominate mechanism for resistance to the tested drugs in these cell lines.