Decreased linezolid uptake in an in vitro-selected linezolid-resistant Staphylococcus epidermidis mutant.

OBJECTIVES: The aim of this study was to characterize the mechanism of resistance to linezolid in an in vitro-selected linezolid-resistant Staphylococcus epidermidis mutant. METHODS: A linezolid-resistant strain of S. epidermidis was selected by serial passages with increasing concentrations of linezolid. The MICs of linezolid, ciprofloxacin, tetracycline, rifampicin, vancomycin, gentamicin, tobramycin, chloramphenicol and oxacillin were determined. The 23S rRNA gene was amplified and sequenced, to search for mutations conferring linezolid resistance. The MIC of linezolid was also determined in the presence of reserpine. Finally, the accumulation of linezolid was measured and quantified by HPLC/UV. RESULTS: The obtained resistant strain had an MIC of linezolid of 64 mg/L and was stable after several passages on blood agar. The MIC measured in the presence of 25 mg/L reserpine, an efflux pump inhibitor, was not altered (MIC of 64 mg/L). The sequence of the 23S rRNA gene showed that the mutation G2576T (Escherichia coli numbering) was not present and no other mutation was found. An analysis of the accumulation of linezolid was performed, comparing the uptake of the resistant strain with that of the susceptible one. This showed that the resistant strain had significantly lower levels of linezolid accumulation than its susceptible parental strain. CONCLUSIONS: The mechanism of resistance to linezolid, in this resistant strain, may be related to a decrease in the antimicrobial uptake. This new mechanism of resistance was also related to a little loss of fitness.

A bioavailability/bioequivalence and pharmacokinetic study of two oral doses of torasemide (5 and 10 mg): prolonged-release versus the conventional formulation.

1. The main objective of the present study was to compare the bioavailability/bioequivalence of a new prolonged-release (PR) formulation of torasemide with an immediate-release (IR) formulation. In addition, we assessed the pharmacokinetics of both formulations, as well as the urine pharmacodynamics. 2. Two doses (5 and 10 mg) of PR torasemide were compared with the same doses of IR torasemide in a single-blind, single-dose, two-treatment, two-period, cross-over, sequence-randomized clinical trial in 20 healthy volunteers (two groups; n = 10 in each group). Torasemide plasma concentrations were measured by high-pressure liquid chromatography-electrospray ionization mass spectrometry. Torasemide urine concentrations, the diuretic effect of torasemide, urine electrolytes and urine density were also determined. 3. Plasma bioequivalence parameters, based on logged values, were as follows: (i) in the 5 mg group, the area under the plasma drug concentration-time curve from t = 0 to last measurable drug concentration at time t (AUC(0-t)) tablet ratio was 1.03 (90% confidence interval (CI) 0.91-1.17) and C(max) was 0.82 (90% CI: 0.68-0.98); and (ii) in the 10 mg group, the AUC(0-t) was 1.07 (90% CI 0.99-1.14) and C(max) was 0.68 (90% CI 0.60-0.78). The PR formulation showed a significantly prolonged t(max) compared with the IR formulation. The amount of torasemide recovered in the urine 24 h after administration was higher with the PR formulation for both doses. The natriuretic rate versus torasemide excretion rate for the PR and IR formulations were successfully regressed to a sigmoid E(max) model. Pharmacodynamic urine evaluations were similar with both formulations, although urine volume and urine electrolyte excretion were lower for the PR formulation in the first hour after administration. However, the PR formulation showed higher natriuretic efficiency. No significant adverse events were reported. 4. In conclusion, both formulations of torasemide showed similar systemic exposure (AUC). However, the PR formulation had a lower rate of absorption (lower C(max) and prolonged t(max)). The PR formulation had urinary excretion rates that were associated with a higher natriuretic efficiency and more constant diuresis.

Comparison of repeated-dose pharmacokinetics of prolonged-release and immediate-release torasemide formulations in healthy young volunteers.

The major aim of the study was to compare the pharmacokinetic profile of repeated-dose administration of a prolonged-release (PR) formulation of torasemide with that of an immediate-release (IR) dosage. Sixteen volunteers received one daily dose, on four consecutive days, of 10 mg of torasemide-PR or torasemide-IR in a single-blind, two-treatment, two-period, repeated-dose, cross-over, sequence-randomized clinical trial. Blood samples were collected at various time points on day 1 (single-dose) and on day 4 (repeated-dose) and torasemide concentrations were analysed by LC/MS/MS. Diuretic effect and urine electrolytes were measured. Urinary urgency was subjectively assessed by visual analogue scales. Safety and tolerability were also determined. Based on logged values, bioequivalence parameters, were: on day 1, ratio = 1.07 (90% CI 1.02-1.1), C(max) ratio = 0.69 (90% CI 0.67-0.73); and on day 4, ratio = 1.02 (90% CI 0.98-1.05), C(max) ratio = 0.62 (90% CI 0.55-0.70). PR had longer t(max) than IR and showed significantly lower fluctuations of plasma concentrations. Urine evaluations were similar with both formulations, although PR showed a lower urine volume in the first hours post-administration. Episodes of acute urinary urgency occurred later and were subjectively less intensive with PR. No significant adverse events were reported.

In vitro antifungal activity of sertaconazole compared with nine other drugs against 250 clinical isolates of dermatophytes and Scopulariopsis brevicaulis.

We have tested 250 strains belonging to 15 species of clinically important dermatophytes and Scopulariopsis against ten antifungal drugs using an agar diffusion method (NeoSensitabstrade mark, Rosco, Taastrup, Denmark). Some of the experimental factors were adapted to dermatophyte development, such as temperature (28 vs. 35 degrees C) and time of incubation (2-5 days vs. 21-74 h). The antifungals used are itraconazole, ketoconazole, miconazole, clotrimazole, sertaconazole, terbinafine, tioconazole, fluconazole, isoconazole and econazole. Except for fluconazole, all the drugs tested have shown to be highly effective, especially sertaconazole and terbinafine. Percentages of susceptibility ranged between 94% for terbinafine, 87.6% for sertaconazole and 86.4% clotrimazole; 81.6% econazole; 42.8% fluconazole; 57.2% isoconazole; 78.4% itraconazole; 74.4% ketoconazole; 73.3% miconazole, and 85.2% for tioconazole. Percentages of resistance were similar between sertaconazole and terbinafine (4%) but in contrast to the 48% obtained for fluconazole.

In vitro activity of sertaconazole, fluconazole, ketoconazole, fenticonazole, clotrimazole and itraconazole against pathogenic vaginal yeast isolates.

The in vitro activity of sertaconazole was compared with those of the most commonly used vaginal antimycotic agents--fluconazole, ketoconazole, fenticonazole, clotrimazole and itraconazole--against 94 strains of clinical isolates of Candida spp. using a macrodilution method in Casitone agar medium. The sertaconazole concentration (microgram/ml), at which 90% of the strains were inhibited, was 0.06 for C. albicans, 0.25 for C. glabrata and C. parapsilosis, 1 for C. krusei and 2 for C. tropicalis. These values show that sertaconazole is one of the most active products against yeasts causing vulvovaginal candidiasis, its activity against C. glabrata being particularly relevant.

Sertaconazole: in-vitro antifungal activity against vaginal and other superficial yeast isolates.

The in vitro susceptibilities of 183 clinical yeast isolates to sertaconazole (STZ) were compared to their susceptibilities to clotrimazole (CTZ), econazole (ECZ), ketoconazole (KTZ), miconazole (MNZ), fluconazole (FLZ), itraconazole (ITZ), tioconazole (TCZ), amphotericin B (AMB) and flucytosine (5FC) by using a commercial agar diffusion method. Strains were isolated from vaginal and other superficial clinical samples (18 species of Candida and five strains belonging to other yeast genera). Only one strain (0.5%) was resistant to STZ out of 87.4% of susceptible strains (n=160). The percentage of susceptible strains was higher than those obtained with the other agents evaluated and the percentage of resistant strains was lower than for most of the other antifungals. The pattern of susceptibility of C. albicans to STZ, TCZ, ITZ and CLZ was similar and superior to the pattern of susceptibility of this species to MNZ, ECZ, FLZ, 5FC and KTZ. C. dubliniensis was more susceptible to STZ, MNZ, MNZ, FLZ, ITZ, CLZ than to TCZ, ECZ, 5FC, AMB or KTZ. Ten susceptible strains to STZ were resistant to FLZ and one strain was resistant to ITZ. The overall antifungal activity of STZ in vitro against a wide range of clinically important yeasts from vaginal and cutaneous samples indicates the therapeutic potential of this agent for the treatment of infections caused by these fungi. However, the activity of STZ and the clinical value of in vitro data need to be verified in human clinical trials.

The correlation between epidermal growth factor levels in saliva and the severity of oral mucositis during oropharyngeal radiation therapy.

BACKGROUND: Epidermal growth factor (EGF) is present in biologic fluids, including saliva, and plays a role in maintenance of the epithelial barrier and in healing of damaged mucosa. The purpose of this study was to assess the relation between salivary EGF and the severity of oral mucositis in patients with carcinoma of the head and neck during radiation therapy. METHODS: Whole resting saliva (WRS) and whole stimulated saliva (WSS) were collected prior to radiation and each week during radiation treatment for 11 men and 7 women. Oral mucositis was evaluated using the National Cancer Institute (NCI) scale of 0-4 and the Oral Mucositis Assessment Scale (OMAS), which evaluates the extent of erythema (scale of 0-2) and ulcerations (scale of 0-3) in nine oral sites. The overall OMAS score of 0-45 reflected the mucosal condition. EGF was assayed in the saliva specimens. RESULTS: The total mean radiation dose delivered to the head and neck was 5667 centigrays (cGy) in a mean of 24 fractions. Ulcerative oral mucositis occurred in 94% of patients. The mean OMAS score ranged from 2.83 in the first week of treatment to 14.77 in the fifth week. The mean WRS and WSS volumes decreased significantly from pretreatment to the first week of radiation treatment and then remained stable. A similar pattern was seen for the mean total output of EGF. A significant and negative correlation was found between higher levels of EGF in stimulated saliva and low OMAS score, reflecting less severe erythema and ulceration. A general trend showing that less tissue damage was associated with a higher EGF level in resting saliva also was illustrated. EGF levels were correlated with the OMAS score; however, no correlation was found when assessing the NCI score, which combines tissue damage with function and symptoms in a single score. CONCLUSIONS: Radiation-induced mucositis appeared to be modified by saliva volume, total EGF, and concentration of EGF in the oral environment. Saliva volume and total EGF output decreased significantly in the first weeks of treatment and remained reduced throughout radiation therapy. The findings suggest that higher levels of EGF in saliva, particularly in stimulated saliva, prior to and during radiation treatment may be associated with less severe mucosal damage due to radiation therapy. It is also postulated that human EGF may affect the development and healing of radiation-damaged mucosa.

Lack of beneficial effect of COX-2 inhibitors in an experimental model of colitis.

Expression of the COX-2 enzyme has been reported in animal models of inflammatory bowel disease (IBD) as well as in patients affected by ulcerative colitis and Crohn's disease. Recently, selective inhibitors of COX-2 have become available. In this study we have evaluated three highly selective COX-2 inhibitors, NS-398, SC-58125 and PD-138387, on the trinitro-benzene sulfonic acid (TNBS) model of colitis in rats. Daily oral administration of the three compounds evaluated up to a dose of 100 mg/kg failed to significantly modify any of the parameters evaluated. Our data show that despite their potent extraintestinal antiinflammatory activity, COX-2 inhibitors do not seem to have any beneficial effect in TNBS colitis and raise the question whether this therapeutic approach would be beneficial in patients with IBD.

Synthesis, structure-activity relationships, and in vivo evaluations of substituted di-tert-butylphenols as a novel class of potent, selective, and orally active cyclooxygenase-2 inhibitors. 1. Thiazolone and oxazolone series.

Selective cyclooxygenase-2 (COX-2) inhibitors have been shown to be potent antiinflammatory agents with fewer side effects than currently marketed nonsteroidal antiinflammatory drugs (NSAIDs). Initial mass screening and subsequent structure-activity relationship (SAR) studies have identified 4b (PD138387) as the most potent and selective COX-2 inhibitor within the thiazolone and oxazolone series of di-tert-butylphenols. Compound 4b has an IC50 of 1.7 microM against recombinant human COX-2 and inhibited COX-2 activity in the J774A.1 cell line with an IC50 of 0.17 microM. It was inactive against purified ovine COX-1 at 100 microM and did not inhibit COX-1 activity in platelets at 20 microM. Compound 4b was also orally active in vivo with an ED40 of 16 mg/kg in the carrageenan footpad edema (CFE) assay and caused no gastrointestinal (GI) damage in rats at the dose of 100 mg/kg but inhibited gastric prostaglandin E2 (PGE2) production in rats' gastric mucosa by 33% following a dose of 100 mg/kg. The SAR studies of this chemical series revealed that the potency and selectivity are very sensitive to minor structural changes. A simple isosteric replacement led to the reversal of selectivity.

Synthesis, structure-activity relationships, and in vivo evaluations of substituted di-tert-butylphenols as a novel class of potent, selective, and orally active cyclooxygenase-2 inhibitors. 2. 1,3,4- and 1,2,4-thiadiazole series.

Two isoforms of the cyclooxygenase (COX) enzyme have been identified: COX-1, which is expressed constitutively, and COX-2, which is induced in inflammation. Recently, it has been shown that selective COX-2 inhibitors have antiinflammatory activity and lack the GI side effects typically associated with NSAIDs. Initial mass screening and subsequent SAR studies have identified 6b (PD164387) as a potent, selective, and orally active COX-2 inhibitor. It had IC50 values of 0.14 and 100 microM against recombinant human COX-2 and purified ovine COX-1, respectively. It inhibited COX-2 activity in the J774A.1 cell line with an IC50 of 0.18 microM and inhibited COX-1 activity in platelets with an IC50 of 3.1 microM. The choline salt of compound 6b was also orally active in vivo with an ED40 of 7. 1 mg/kg in the carrageenan footpad edema (CFE) assay. In vivo studies in rats at a dose of 100 mg/kg showed that this compound inhibited gastric prostaglandin E2 (PGE2) production in gastric mucosa by 77% but caused minimal GI damage. SAR studies of this chemical series revealed that the potency and selectivity are very sensitive to minor structural changes.

Effects of novel anti-inflammatory compounds on healing of acetic acid-induced gastric ulcer in rats.

Nonsteroidal anti-inflammatory drugs often cause development of significant GI lesions. Selective inhibitors of prostaglandin G/H synthase/cyclooxygenase-2 (PGHS-2) enzyme and some dual inhibitors of PGHS/5-lipoxygenase (5-LO) enzymes have been reported to be potent anti-inflammatory compounds that carry a much lower risk of having GI irritating effects. We have evaluated the anti-inflammatory effect and the GI safety profile of three new anti-inflammatory compounds: the selective PGHS-2 inhibitors NS-398 and PD 138387 and the PGHS/5-LO dual inhibitor PD 137968. All the compounds tested showed an anti-inflammatory activity in the carragenan footpad edema test in rats. None of these compounds caused either gastric damage 4 h after p.o. administration of 100 mg/kg in rats or inhibition of PGE2 synthesis in the stomach. However, when administered p.o. at an effective anti-inflammatory dose to rats with pre-existing acetic acid-induced gastric ulcer, NS-398 caused a statistically significant delay of ulcer healing. No impairment of the ulcer healing was observed with the other compounds evaluated. Derivatives of 2,6-di-tert-butylphenol, whose members may act as PGHS-1/PGHS-2 inhibitors, selective PGHS-2 inhibitors or PGHS/5-LO dual inhibitors, are novel anti-inflammatory compounds that are devoid of GI irritating effects and do not affect the rate of pre-existing gastric ulcer healing.

Role of metalloproteinases in the development and healing of acetic acid-induced gastric ulcer in rats.

BACKGROUND/AIMS: Matrix metalloproteinases (MMPs) are believed to be active in connective tissue remodeling associated with various physiological processes and in pathological conditions such as cancer and arthritis. However, the role of MMPs in gastrointestinal ulceration has not been clearly established. Therefore, the aim of this study was to examine the role of collagenase and gelatinases A and B in the development and healing of acetic acid-induced gastric ulcer in rats. METHODS: Gastric ulcer was induced by injecting 20 microliters glacial acetic acid into gastric wall of rat stomachs. To examine whether changes in the ulcer formation and healing phase correlate with MMP activity, Triton X-100/CaCl2 and Tris/CaCl2 (60 degrees C) extracts of stomachs were prepared from controls and animals killed 24 h (formation phase) and 7 days (healing phase) after acetic acid administration. Total collagenase and gelatinase activities were measured using (H3)labeled-acetylated type I collagen or gelatin as substrate, respectively, prepared from rat skin. RESULTS: Twenty-four hours after administration of acetic acid, the mean area of ulcer crater was 51.2 mm2. By day 7, the mean size of ulcer crater was reduced to 35.9 mm2. The mean activity of collagenase in gastric tissue from controls animals was 0.007 U/g tissue. In acetic acid-treated rats, this activity increased to 2.18 U/g at 24 h and declined to 0.69 U/g by day 7. Similarly, total gelatinase activity increased from 20.5 U/g tissue (controls) to 28.8 U/g at 24 h and declined to 23.9 U/g at day 7. Gelatinzymography revealed that gelatinase B levels were greatly increased at 24 h and declined by day 7, whereas the gelatinase A levels remained constant. CONCLUSIONS: The data showed that the formation of acetic acid-induced ulcer in rats is accompanied by an elevation of collagenase and gelatinase B that gradually tend to return to control values during the healing phase.

Assessment of epidermal growth factor in oral secretions of patients receiving radiation therapy for cancer.

Biological response modifiers have been studied in animal models of oral mucositis. We assessed the presence of epidermal growth factor (EGF) in patients during radiation therapy for head and neck cancer. The findings of this preliminary study showed that it is possible to measure the presence of EGF in oral secretions during radiation therapy. EGF was shown to decrease during the course of radiation therapy, and a trend was seen with decreasing EGF and increasing oral ulceration (P = 0.10) and increasing total mucositis score (P = 0.09).

Development and validation of two solid-phase enzyme immunoassays (ELISA) for quantitation of human epidermal growth factors (hEGFs).

PURPOSE: The purpose of the present investigation was to develop and validate two separate enzyme-linked immunosorbent assays (ELISA) for quantitation of exogenous human epidermal growth factor (hEGF1-53) and its truncated fragment (hEGF1-48) in rat plasma. METHODS: The present assay systems were based on the sandwiching of the antigen between a monoclonal mouse anti-hEGF1-53 antibody, pre-coated on a 96-well polystyrene plate, and a polyclonal rabbit anti-hEGF1-48 antibody, which is then detected with a peroxidase-labeled goat anti-rabbit antibody. RESULTS: The calibration curves for hEGF1-48 and hEGF1-53 in plasma were validated over a concentration range of 7.8-250 and 62.5-1000 pg/ml, respectively. Determined from replicate assays of hEGF1-48 quality control samples, the intra-assay precision and accuracy were < or = 8.8% RSD and within +/- 9.8%; and the inter-assay precision and accuracy were < or = 14.8% RSD and within +/- 9.7% RE, respectively. Determined from replicate assays of hEGF1-53 quality control samples, the intra-assay precision and accuracy were < or = 10.0% RSD and within +/- 8.5%; and the inter-assay precision and accuracy were < or = 10.0% RSD and within +/- 5.7% RE, respectively. The limit of quantitation of the hEGF1-48 and hEGF1-53 assay using 200 microliters plasma per well is 7.8 and 62.5 pg/ml, respectively. These two ELISA methods are specific to hEGFs and do not cross-react with mouse EGF or other growth factors (TGF alpha, TGF beta, PDGF, and FGF) or lymphokines (IL1 beta and TNF alpha). These validated methods have been routinely applied to assay of plasma samples from various pharmacokinetic studies in rats receiving intravenous hEGFs. Both assay methods were also adapted to assay endogenous hEGFs in biological fluids of different animal species. CONCLUSIONS: Two sensitive ELISA methods have been validated for quantitation of hEGF1-53 and hEGF1-48 in rat plasma. Their utility has been demonstrated in the application of assaying immunoreactive concentration of exogenous and endogenous epidermal growth factors.

Increased gastroduodenal concentrations of transforming growth factor alpha in adaptation to aspirin in monkeys and rats.

BACKGROUND & AIMS: The mechanism by which gastric mucosa becomes more resistant to damage by repeated aspirin administration is not known. Transforming growth factor alpha (TGF-alpha) and epidermal growth factor (EGF) prevent drug-induced gastric injury. The aim of this study was to determine whether gastroduodenal tissue levels of TGF-alpha and EGF protein were altered during adaptation to aspirin-induced injury in monkeys and rats in vivo. METHODS: Animals were given aspirin daily for up to 28 days. Gross mucosal injury was assessed by computerized image analysis in rats and by endoscopy in monkeys. Mucosal concentrations of TGF-alpha and EGF were quantitated by radioimmunoassays from endoscopic biopsy samples in monkeys and from scraped mucosa in rats. RESULTS: Long-term administration of aspirin caused a significant increase in gastric and duodenal tissue levels of TGF-alpha in monkeys and rats; the increased levels of TGF-alpha significantly correlated with the decrease in aspirin-induced injury. No change in the gastroduodenal tissue levels of EGF was observed. Adaptation was not associated with any significant change in basal gastric acid secretion in monkeys and occurred despite a significant decrease in gastric mucin in rats. CONCLUSIONS: Adaptation of the gastric mucosa to the damaging effect of aspirin is associated with a significant and specific increase in TGF-alpha protein in the gastroduodenum.

Immunohistochemical testing of a new anti-EGF antibody.

A new polyclonal anti-EGF antibody, raised in rabbits against a fragment of the human EGF molecule was evaluated for its usefulness in immunohistochemistry. Various combinations of fixation, concentration, temperature, time and staining procedures were tested on rat submandibulary glands. The best results were obtained using 10% buffered or neutral formalin fixation for 24 hours, 1:1000 dilution of primary antibody, incubation time of 60 min with addition of 10% neutral rat serum to the secondary antibody and the ABC staining method. Staining of different human and rat tissues demonstrated strong reactivity in human parotid glands and both human and rat kidney. Moderate reactivity was found in human and rat gastric, duodenal, colonic as well as buccal mucosa.

Clinical applications of epidermal growth factor.

Epidermal growth factor (EGF) is a molecule with a broad pharmacological activity which has been used clinically, with promising results, to treat patients affected by necrotizing enterocolitis, Zollinger-Ellison syndrome, gastrointestinal ulceration and congenital microvillus atrophy. In theory, EGF may find a clinical application in a variety of other pathologies of both the gastrointestinal tract and other systems. Examples of gastrointestinal diseases that could benefit from treatment with EGF include colitis, gastrointestinal ulcerations of various causes, atrophic conditions, conditions of defective maturation and development and even cancer. However, the clinical use of EGF may be associated with a variety of problems and side-effects; careful selection of patients and evaluation of risk-benefit ratios are required.

BPC-15 reduces trinitrobenzene sulfonic acid-induced colonic damage in rats.

The effect of BPC-15 (Booly Protection Compound-15) was evaluated in a rat model of colonic injury. A single intracolonic administration of trinitrobenzene sulfonic acid (TNBS) dissolved in ethanol induces severe colonic damage, which is characterized by areas of necrosis surrounded by areas of acute inflammation. The damage is associated with high myeloperoxidase (MPO) activity, mainly as a reflection of neutrophilic infiltration into the damaged tissue. In this study, 1 hr before a single intracolonic administration of 50 mg/kg of TNBS in 50% ethanol, the animals were treated with one of the following doses of BPC-15: 0.0001, 0.001, 0.01, 0.1, 1 or 10 nmol/kg administered i.p. or with a dose of 10 nmol/kg administered intracolonically. The animals were sacrificed 3 days later and the extent of colonic necrosis and hyperemia was measured with an image analyzer. The i.p. administration of BPC-15 significantly reduced the extent of TNBS-induced colonic damage in a dose-dependent manner. This was associated with a statistically significant and dose-dependent reduction in colonic tissue MPO activity. At the dose tested (10 nmol/kg), intracolonic administration of BPC-15 did not significantly reduce either the extent of the colonic damage or the increase in MPO activity induced by TNBS. In conclusion, this study showed that i.p. administration of BPC-15 reduced TNBS-induced colonic damage in rats.

Effect of transforming growth factor-alpha on gastric acid secretion in rats and monkeys.

The effect of transforming growth factor-alpha was studied in histamine-stimulated gastric acid secretion in monkeys and in pylorus-ligated rats. In monkeys, transforming growth factor-alpha given intravenously in a stepwise manner gradually reduced gastric acid secretion. A dose of 0.1 mmol/kg induced about a 50% inhibition of gastric acid output, while about 100% inhibition of the same parameter, was observed after a dose of 1 nmol/kg. Following a single administration of 1 nmol/kg intravenously in monkey, the maximum inhibitory effect on gastric acid output was reached 60 min after the administration of the drug, when a 91.8% inhibition was observed. Pretreatment values were reached 210-240 min after transforming growth factor-alpha administration. In pylorus-ligated rats, transforming growth factor-alpha, at doses of 9 and 18 nmol/kg produced an almost complete inhibition of gastric acid secretion. In this model, the ED50 was calculated to be 4.5 nmol/kg. Comparison with epidermal growth factor on the same models of gastric acid secretion showed that these two compounds have similar inhibitory potency. However, the effect of transforming growth factor-alpha on gastric acid secretion in monkeys was shorter lasting than that of epidermal growth factor.

Effect of h-EGF and h-EGF 1-48 on histamine-stimulated gastric acid secretion in rats and monkeys.

The effect of human epidermal growth factor (h-EGF) and its derivative human epidermal growth factor 1-48 (h-EGF 1-48) on histamine-stimulated gastric acid secretion was studied in monkeys and rats. In monkeys, both h-EGF and h-EGF 1-48 given intravenously (i.v.) in a stepwise manner and in doses ranging from 0.01 to 10 nmol/kg, gradually suppressed gastric acid secretion. At the highest dose tested, both compounds essentially abolished gastric acid output. In the same animals, i.v. administration of 1 nmol/kg of h-EGF or h-EGF 1-48 caused an inhibition of gastric acid output that reached a peak at 90 and 60 min after the administration of h-EGF or h-EGF 1-48 respectively. After this maximum gastric inhibitory effect, a gradual return toward pre-injection values was observed. In rats, after subcutaneous (sc) administration, both h-EGF and h-EGF 1-48 dose-dependently inhibited histamine-stimulated gastric acid output as measured 60 min after the administration of the compounds. The maximum inhibitory activity on gastric acid output, observed at a dose of 100 nmol/kg, was 74.4% and 76.0% for h-EGF and h-EGF 1-48 respectively. The same dose of both compounds, however, failed to significantly inhibit gastric acid secretion when administered orally. In all the studies h-EGF 1-48 showed activity and potency comparable to h-EGF.(ABSTRACT TRUNCATED AT 250 WORDS)