"Fabrication of pellets via extrusion-spheronization for engineered delivery of Famotidine through specialized straws for Paediatrics"

OBJECTIVE

A simple and efficient drug delivery device was designed, viz. specialized straw comprising of famotidine-loaded fast disintegrating pellets.

SIGNIFICANCE

Pediatric dosage forms are designed and developed considering the palatability in children of all ages. This specialized straw was intended for pediatrics presenting with dysphagia or associated symptoms.

METHODS

The pellets were formulated using an extruder spheronization technique incorporated with Kyron T-314 as a super disintegrant. These pellets were characterized for their micromeritic properties, disintegration, and in vitro drug release. The specialized straw was evaluated for various parameters like flow rate of water siphoned through the straw and solvation volume.

RESULTS

Pellets were found to have excellent flow properties, disintegration time was found to be 25-30s, and dissolution studies showed 96.1% drug release in 45min. In vitro flow rate was determined to simulate sipping action through this specialized straw. The results indicated that water flowing through the hollow straw at the rate of 13.8±1.3 mLs-1, when tested in prefilled specialized straw, 6.3±1.1 mLs-1 flow rate was observed to be sufficient to dissolve the pellets.

CONCLUSION

Finally, the fast-disintegrating pellets demonstrated excellent in vitro performance and relative ease of manufacturing as compared to other solid dosage forms. Furthermore, the developed specialized straw can be used as a convenient and attractive drug delivery device for pediatrics.

Charge transfer complex-based spectrophotometric analysis of famotidine in pure and pharmaceutical dosage forms

A straightforward and efficient spectrum technique was created using Ortho-chloranil as the electron acceptor (-acceptor) in a charge transfer (CT) complex formation reaction to determine the concentration of famotidine (FMD) in solutions. Compared to the double-distilled blank solution, the reaction result detected a definite violet colour at a maximum absorption wavelength of 546 nm, For concentrations range 2-28 µg/ml, the technique demonstrated excellent compliance with Beer-Law and Lambert's, as evidenced by its molar absorptivity of 2159.648 L mol-1 cm-1. Lower detection limits of 0.3024 µg/ml and 1.471 µg/ml, respectively, were discovered. The complexes of famotidine and Ortho-chloranil were found to have a 2:1 stoichiometry. Additionally, the suggested approach effectively estimated famotidine concentrations in pharmaceutical formulations, particularly in tablet form.

Wastewater surveillance of pharmaceuticals during the COVID-19 pandemic in Mexico City and the Mezquital Valley: A comprehensive environmental risk assessment

This study tracked five pharmaceutically active compounds (PhACs) in Mexico City's sewage, namely, famotidine, indomethacin, dexamethasone, azithromycin, and ivermectin, which were used to treat COVID-19. The monitoring campaign was carried out over 30 months (May 2020 to November 2022), covering the five COVID-19 waves in Mexico. In the Central Emitter, the main sewage outflow, famotidine displayed levels of 132.57 ± 28.16 ng L-1 (range from < LOQ to 189.1 ng L-1), followed by indomethacin (average 672.46 ± 116.4 ng L-1, range from 516.7 to 945.2 ng L-1), dexamethasone (average 610.4 ± 225.7 ng L-1, range from 233.4 to 1044.5 ng L-1), azithromycin (average 4436.2 ± 903.6 ng L-1, range from 2873.7 to 5819.6 ng L-1), and ivermectin (average 3413.3 ± 1244.6 ng L-1, range from 1219.8 to 4622.4 ng L-1). The concentrations of dexamethasone, azithromycin and ivermectin were higher in sewage from a temporary COVID-19 care unit, by a factor of 3.48, 3.52 and 2.55, respectively, compared with those found in municipal wastewater. In the effluent of the Atotonilco Wastewater Treatment Plant (AWWTP), which treats near 60 % of the Mexico City's sewage, famotidine was absent, while concentrations of indomethacin, dexamethasone, azithromycin and ivermectin were 78.2 %, 76.7 %, 74.4 %, and 88.1 % lower than those in the influent, respectively. The occurrence of PhACs in treated and untreated wastewater resulted in medium to high environmental risk since Mexico City's wastewater is reused for irrigation in the Mezquital Valley. There, PhACs were found in irrigation canals at lower levels than those observed in Mexico City throughout the monitoring. On the other hand, famotidine, indomethacin, and dexamethasone were not found in surface water resulting from the infiltration of wastewater through soil in Mezquital Valley, while azithromycin and ivermectin sporadically appeared in surface water samples collected through 2021. Using an optimized risk assessment based on a semi-probabilistic approach, the PhACs were prioritized as ivermectin > azithromycin > dexamethasone > famotidine > indomethacin.

GC Analysis of Metformin, Ranitidine and Famotidine from Pharmaceuticals and Human Serum

A method has been designed based on gas chromatography with flame ionization detection (FID) for the separation and analyses of ranitidine, famotidine and metformin after pre-column derivatization with trifluoroacetylacetone and ethyl chloroformate. DB-1 (30 m × 0.32 mm id) column with film thickness 0.25 μm was used for the separation at an initial temperature of column was 100°C for 2 min, and ramping at 20°C/min up to 250°C, with a hold time of 3 min. The rate of nitrogen flow was 2.5 mL/min and FID was used for detection. Complete separation was obtained between all the three drugs including excess of derivatization reagents. Linear calibration curves and detection limits were obtained in the ranges 0.1-30 μg/mL and 0.011-0.015 μg/mL. The procedure was repeatable in terms of peak heights/peak areas and retention time (n = 5) for derivatization, quantitation and separation with relative standard deviations (RSDs) within 2.0-3.0%. The approach was examined for the analyses of drug products and serum after the intake of the drugs by healthy volunteers, and recoveries were obtained within 95-98% with RSDs 2.4-3.1%.

Highlights in TMPRSS2 inhibition mechanism with guanidine derivatives approved drugs for COVID-19 treatment

Transmembrane protease serine 2 (TMPRSS2) has been identified as a critical key for the entry of coronaviruses into human cells by cleaving and activating the spike protein of SARS-CoV-2. To block the TMPRSS2 function, 18 approved drugs, containing the guanidine group were tested against TMPRSS2's ectodomain (7MEQ). Among these drugs, Famotidine, Argatroban, Guanadrel and Guanethidine strongly binds with TMPRSS2 S1 pocket with estimated Fullfitness energies of -1847.12, -1630.87, -1605.81 and -1600.52 kcal/mol, respectively. A significant number of non-covalent interactions such as hydrogen bonding, hydrophobic and electrostatic interactions were detected in protein-ligand complexes. In addition, the ADMET analysis revealed a perfect concurrence with the aptitude of these drugs to be developed as an anti-SARS-CoV-2 therapeutics. Further, MD simulation and binding free energy calculations were performed to evaluate the dynamic behavior and stability of protein-ligand complexes. The results obtained herein highlight the enhanced stability and good binding affinities of the Argatroban and Famotidine towards the target protein, hence might act as new scaffolds for TMPRSS2 inhibition.Communicated by Ramaswamy H. Sarma.

Development of a Data-Driven Reference Standard for Adverse Drug Reaction (RS-ADR) Signal Assessment (Preprint)

Background

Pharmacovigilance using real-world data (RWD), such as multicenter electronic health records (EHRs), yields massively parallel adverse drug reaction (ADR) signals. However, proper validation of computationally detected ADR signals is not possible due to the lack of a reference standard for positive and negative associations.

Objective

This study aimed to develop a reference standard for ADR (RS-ADR) to streamline the systematic detection, assessment, and understanding of almost all drug-ADR associations suggested by RWD analyses.

Methods

We integrated well-known reference sets for drug-ADR pairs, including Side Effect Resource, Observational Medical Outcomes Partnership, and EU-ADR. We created a pharmacovigilance dictionary using controlled vocabularies and systematically annotated EHR data. Drug-ADR associations computed from MetaLAB and MetaNurse analyses of multicenter EHRs and extracted from the Food and Drug Administration Adverse Event Reporting System were integrated as “empirically determined” positive and negative reference sets by means of cross-validation between institutions.

Results

The RS-ADR consisted of 1344 drugs, 4485 ADRs, and 6,027,840 drug-ADR pairs with positive and negative consensus votes as pharmacovigilance reference sets. After the curation of the initial version of RS-ADR, novel ADR signals such as “famotidine–hepatic function abnormal” were detected and reasonably validated by RS-ADR. Although the validation of the entire reference standard is challenging, especially with this initial version, the reference standard will improve as more RWD participate in the consensus voting with advanced pharmacovigilance dictionaries and analytic algorithms. One can check if a drug-ADR pair has been reported by our web-based search interface for RS-ADRs.

Conclusions

RS-ADRs enriched with the pharmacovigilance dictionary, ADR knowledge, and real-world evidence from EHRs may streamline the systematic detection, evaluation, and causality assessment of computationally detected ADR signals.

Molecular recognizable ion-paired complex formation between diclofenac/indomethacin and famotidine/cimetidine regulates their aqueous solubility

This study focused on the physicochemical interactions between acidic and basic drugs in aqueous solutions. Their ion pair interactions were evaluated in an in vitro study. The model non-steroid anti-inflammatory drugs (NSAIDs), indomethacin (INM) and diclofenac (DIC), were used as acidic and hydrophobic drugs, whereas cimetidine (CIM), famotidine (FAM), and imidazole (IMD) were used as basic additives with heterocyclic moieties. The drug mixtures were evaluated by thermal analysis, dissolution test, nuclear magnetic resonance (NMR) spectroscopy, and mass spectroscopy. The fusion enthalpy of DIC-CIM, INM-CIM, and INM-arginine (ARG) sample was calculated based on melting temperature transformation. The DIC mixture with CIM, IMD, antipyrine (ANT), and ARG showed enhanced solubility, whereas the DIC-FAM mixture sample showed a decreased solubility. Electrospray ionization mass spectroscopy was carried out to detect binary mixtures. The interactions in DIC-FAM mixture sample were found between the carboxyl group of DIC and the amine groups of FAM by NMR. These findings were suggested that DIC-FAM mixture samples construct ion pair complexes based on the theory of Bjerrum. Moreover, the acid model drug and basic model drug also can be constructed 1:1 complexes that affects their solubility in the solvent of water type.

Efficacy of oral fecal bacteriotherapy in rhesus macaques (Macaca mulatta) with chronic diarrhea

Chronic diarrhea remains the principal burden in providing health care for nonhuman primates in biomedical research facilities. Although the exact etiology continues to puzzle nonhuman primate clinicians, recent research in humans has shown that restoring the indigenous microbial diversity may be successful in resolving cases of chronic diarrhea when other treatment modalities have failed. The process of restoring this microbial balance, known as fecal bacteriotherapy, uses the complete flora from a normal donor as a therapeutic probiotic mixture. In the current study, Indian-origin rhesus macaques were randomized into treatment (n=7) and control (n=6) groups to determine whether orally administered fecal bacteriotherapy would reduce the overall incidence of chronic diarrhea during a 60-d follow-up period in the treatment group compared with control macaques, which received a placebo. Although the treatment effect, determined by comparing the baseline fecal scores of the treatment and control groups, did not reach statistical significance, preprocedure and postprocedure fecal scores in the treatment group differed significantly. These findings are encouraging, and we hope that our study will motivate larger studies evaluating the use of fecal bacteriotherapy in nonhuman primates.

Effects of antiulcer agents on healing of mepirizole-induced duodenal ulcers in rats

Healing processes of duodenal ulcers induced by mepirizole and effects of several drugs on the ulcer healing were studied in rats. Mepirizole-induced duodenal ulcers, except for the perforated ones within 3 days after ulceration, gradually diminished in size and depth by the 15th day. Several ulcers persisted for up to 40 days, but complete healing in all rats occurred by the 60th day after ulceration. Oral cimetidine and YM-11170 (both histamine H2-receptor antagonists), at 200 and 30 mg/kg twice daily for 10 days, respectively, significantly accelerated the healing of duodenal ulcers. Oral Maalox (antacid) at 1,000 mg/kg thrice daily and propantheline (anticholinergic agent) at 30 mg/kg twice daily tended to accelerate the healing of the ulcers. Oral 16,16-dimethyl PGE2, at 0.03 and 0.1 mg/kg twice daily, resulted in a delayed healing of the ulcers. Mepirizole-induced duodenal ulcers appear to be a useful model for the study of ulcer healing and for screening of antiulcer drugs.

Famotidine for gastric radiography

The effectiveness of famotidine (20 mg) in suppressing nocturnal gastric secretion during preparation for gastric radiography was studied in 243 patients. The gastric juice volume was calculated from a single upright radiograph of the stomach. The overall percentage suppression of nocturnal gastric secretion by famotidine was 60%, while it was 47% in patients with upper gastrointestinal symptoms. Radiological examinations were of diagnostic quality in 82% of the controls and 91% of the famotidine group; excellent film were obtained in 45% and 3%, respectively. Our findings suggest that famotidine could be a useful pretreatment for barium meal examinations.

[Clinical studies on the risk of aspiration pneumonitis with respect to gastric pH and volume--effects of age, induction time, H2-blocker and anesthetic technique]

The age-related risk of aspiration pneumonitis was studied by measuring gastric pH and volume in patients undergoing elective surgery. Control group (without administration of H2-blocker) showed the greatest risk in 12-19 yr sub-group, and the risk decreased with age. Famotidine (H2-blocker) was very useful for premedication in patients of all ages, though slightly uncertain in 12-19 yr sub-group. In 12-19 yr sub-group, the proportion of patients with gastric fluid volume greater than or equal to 0.4 ml.kg-1 was significantly greater in PM group (induction of anesthesia in the afternoon) than AM group (in the morning). Furthermore, the effects of anesthetic technique on gastric pH were examined. Gastric pH increased significantly during N2O-O2-halothane and N2O-O2-enflurane anesthesia; while during N2O-O2-epidural and N2O-O2-fentanyl anesthesia, gastric pH was unchanged significantly and stayed low.

Structural study of histamine H2-receptor antagonists. Five 3-[2-(diamino-methyleneamino)-4-thiazolylmethylthio]propionamidine and -amide derivatives

(1) N2-Cyano-3-[2-(diaminomethyleneamino)-4- thiazolylmethylthio]propionamidine monohydrate, C9H13N7S2.H2O, Mr = 301.39, P1, a = 11.089 (4), b = 9.130 (6), c = 7.033 (5) A, alpha = 100.99 (6), beta = 83.86 (5), gamma = 86.80 (7) degrees, V = 692.9 (6) A3, Z = 2, Dm = 1.443 (2), Dx = 1.444 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu = 34.86 cm-1, F(000) = 316, T = 293 K, R = 0.043 for 2219 reflections. (2) 3-[2-Diaminomethyleneamino)-4- thiazolylmethylthio]-N2-sulfamoylpropionamidine (famotidine) hydrochloride, C8H15N7O2S3.HCl, Mr = 373.90, Cc, a = 15.205 (3), b = 14.442 (3), c = 9.262 (1) A, beta = 124.00 (5) degrees, V = 1686.1 (7) A3, Z = 4, Dm = 1.470 (2), Dx = 1.473 g cm-3, mu(Cu K alpha) = 56.09 cm-1, F(000) = 776, T = 293 K, R = 0.036 for 1411 reflections. (3) 3-[2-(Diaminomethyleneamino)-4-thiazolylmethylthio]-propi ona mide, C8H13N5OS2, Mr = 259.35, P2(1)2(1)2(1), a = 5.472 (1), b = 18.260 (5), c = 11.890 (3) A, V = 1188.0 (5) A3, Z = 4, Dm = 1.448 (1), Dx = 1.450 g cm-3, mu(Cu K alpha) = 39.26 cm-1, F(000) = 544, T = 293 K, R = 0.036 for 1260 reflections.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of nocturnal acid secretion with famotidine accelerates gastric ulcer healing

Although nocturnal acid secretion has been emphasized in the pathophysiology and treatment of duodenal ulcer, its importance in gastric ulcer disease has been questioned. To explore this area, this multicenter U.S. trial compared the effect of a once-daily nighttime dose of H2-receptor antagonist with placebo on the healing of gastric ulcer and relief of associated symptoms. One hundred fifty-seven patients with endoscopically verified benign gastric ulcers were randomized in a double-blind fashion to either famotidine (40 mg at bedtime) or placebo. Antacid tablets were allowed as needed. The healing rates for famotidine were 45%, 66%, and 78% at weeks 4, 6, and 8, respectively. In comparison, placebo healing rates were 39%, 44%, and 64%. These differences were statistically significant in favor of famotidine at weeks 6 (p less than or equal to 0.01) and 8 (p less than or equal to 0.05), as well as in a life-table analysis (p less than or equal to 0.05). Nocturnal famotidine was also significantly better than placebo with respect to time to complete relief of pain and to the percentage of patients with complete relief of pain. No concomitant factor (including ulcer size, ulcer location, smoking history, or regular alcohol use) affected healing rates in this study. Famotidine was well-tolerated and no serious clinical or laboratory adverse effects were judged to be related to this dosing regimen of famotidine. In conclusion, suppression of nocturnal acid secretion with famotidine (40 mg at bedtime) was more effective than placebo in promoting the healing of acute benign gastric ulcer and its associated symptoms. The results of this study suggest that suppression of nocturnal acid secretion alone is as effective as "around the clock" acid suppression in the healing of benign gastric ulcer.

Use of microbleeding and an ultrathin endoscope to assess gastric mucosal protection by famotidine

We have developed an ultrathin endoscope for repeated endoscopy in unsedated subjects and used it with assessment of bleeding rates to investigate aspirin-induced gastric mucosal injury and its prevention by famotidine. Compared with placebo, 900 mg of aspirin b.i.d. taken for 48 h caused significant endoscopic injury (median grade 3.5, interquartile range 2-4, modified Lanza scale, p less than 0.01), with an increase in mucosal bleeding from 2.0 (geometric mean; 95% confidence limits, 1.1-3.9) microliters/12 min, to 8.3 (2.4-28.8) microliters/12 min (p less than 0.05). Famotidine (20 mg b.i.d.) raised intragastric pH and reduced endoscopic antral injury (median 1.5, interquartile range 0.5-2, p less than 0.05) and bleeding [3.1 (1.2-8.3) microliters/12 min, p less than 0.01] to levels not significantly different from placebo [1 (0-1) and 2.0 (1.1-3.9) microliters/12 min, respectively]. By contrast, 2 mg of famotidine b.i.d. had no significant effect on intragastric pH endoscopic injury or bleeding rates. The two assessments of gastric mucosal injury correlated strongly (r = 0.71, p less than 0.01). The reduction in bleeding with famotidine tended to be higher, the greater the intragastric pH (r = 0.66, p = 0.057). Ultrathin endoscopy is a simple technique that validates gastric mucosal bleeding as a measure of acute gastric mucosal injury in humans. Acid suppression is an effective method of ameliorating this injury.

A critical review of continuous infusion H2 receptor therapy

Recent studies suggest that continuous infusions of H2-receptor antagonists may be more effective than intermittent iv therapy to control gastric pH for the prevention of stress ulcers. Infusions of cimetidine, ranitidine, and famotidine have been shown either to have a beneficial clinical effect, to control gastric acid secretion, to maintain gastric pH greater than 4, or to have pharmacokinetic properties similar to intermittent doses. In addition, some evidence suggests that continuous infusions may permit the use of lower doses, leading to cost savings. However, as yet there have been no trials that directly compare continuous and intermittent regimens and show improved outcomes with a continuous regimen. Since candidates for parenteral administration of H2-receptor antagonists are most common in the ICU, several practical issues must be addressed. Patients who receive total parenteral nutrition (TPN) may be suitable candidates for continuous infusions of H2-blockers since these agents can be given in the same container as TPN solutions. These patients also usually have a parenteral access site and infusion pump dedicated to TPN administration. In other patients, drug incompatibilities, limited iv access lines, or a lack of infusion pumps may require frequent interruptions of the infusion in order to administer additional medications, which may lead to a loss of gastric pH control. In most patients, administration of an H2-blocker regimen which maintains consistent pH control after intermittent administration may be the most practical method by which to administer these agents.

Frequent non-response to histamine H2-receptor antagonists in cirrhotics

The effect of ranitidine 300 mg po given at 1800 h (famotidine 40 mg/cimetidine 800 mg) on the night time gastric pH was tested using longterm intragastric pH monitoring in 27 patients with and 32 patients without liver cirrhosis. A rise in the gastric pH above 4.0 for more than six hours between 1800 h and 0600 h was considered as sufficient effect (response) of the H2-receptor antagonists on gastric acidity. Among the patients with cirrhosis, there were significantly (p less than 0.005) more non-responders to ranitidine (16 of 27 patients) than in the control group (six of 32). When 13 of the 22 non-responders to ranitidine were subsequently treated with famotidine, only two showed a sufficient rise in their gastric pH. Of the 11 patients not responding to both H2-receptor antagonists, 10 were finally treated with cimetidine and eight did not respond. Plasma levels of all three drugs measured two and four hours after oral administration were not significantly different between cirrhotic and noncirrhotic patients as well as between responders and non-responders. In addition, in all patients plasma levels were far above the corresponding IC50 values. Therefore, differences in the absorption and plasma levels of these drugs cannot account for the frequent non-response in cirrhotics.

Famotidine therapy for active duodenal ulcers. A multivariate analysis of factors affecting early healing

OBJECTIVE

To identify factors that influence the rate of healing of duodenal ulcers.

DESIGN

A stepwise multivariable statistical analysis of patients with duodenal ulcer in a multicenter, prospective, open-label study. Healing was assessed by endoscopy at 4 or 8 weeks. Antacid use and symptoms were recorded in a daily diary.

SUBJECTS

Of 135 patients, ages 19 to 86, 50% had a previous duodenal ulcer, 46.7% smoked, and 34.8% had melena or hematemesis.

INTERVENTIONS

Famotidine, 40 mg orally, at bedtime for 4 or 8 weeks depending on endoscopic evaluation of ulcer healing. Limited antacid use was permitted.

SETTING

Office practices, hospital practices, and university-based medical centers.

MEASUREMENTS AND MAIN RESULTS

Multivariable analysis identified five independent predictors present at the time of diagnosis that influenced ulcer healing. The odds of not healing for each risk factor after simultaneous adjustment of the other risk factors were as follows: alcohol use, 6.5 (CI, 2.0 to 20.7, P less than 0.002); ulcer size greater than 10 mm, 4.2 (CI, 1.5 to 11.6, P less than 0.005), bleeding symptoms. 3.5 (CI, 1.2 to 10.2, P less than 0.03); and a previous duodenal ulcer, 3.1 (CI, 1.05 to 9.0, P less than 0.04). The use of salicylates or nonsteroidal anti-inflammatory drugs before treatment was associated with an improved odds of healing (adjusted odds ratio, 0.2; CI, 0.1 to 0.9, P less than 0.04). The percentage of patients achieving complete ulcer healing after 4 weeks of famotidine decreased inversely with the number of risk factors present, ulcer size, and the quantity of daily alcohol use (P less than 0.001). Fewer than half of those patients who still had severe pain at day 7 achieved healing at 4 weeks (P less than 0.001). In contrast, smoking and 23 other factors had no statistically discernible effect on ulcer healing with famotidine.

CONCLUSIONS

Five variables present at the time of diagnosis independently influenced the rate of ulcer healing at 4 weeks: alcohol use, ulcer size, bleeding symptoms, a previous duodenal ulcer, and previous use of salicylates or nonsteroidal anti-inflammatory drugs.

Impaired bioavailability of famotidine given concurrently with a potent antacid

The effect of a high potency antacid on the oral bioavailability of a single dose of famotidine (40 mg) was evaluated in normal volunteers according to a randomized cross-over design. Ingestion of the antacid concurrently with famotidine resulted in a significant reduction of peak plasma famotidine concentration (from 156 +/- 22 to 104 +/- 7, P less than 0.05) and area under the famotidine plasma concentration curve (from 956 +/- 125 to 607 +/- 56, P less than 0.02). No significant interaction was observed when the antacid was ingested 2 hours after famotidine administration.

Community-based study coupled with a patient registry

A multicenter, double-blind, randomized controlled trial comparing the efficacy and safety of famotidine with ranitidine in the treatment of acute, benign gastric ulcer disease was coupled with a community-based gastric ulcer disease registry. One hundred ninety-five patients with endoscopically documented gastric ulcer disease were enrolled in the trial and randomly allocated to treatment with either famotidine 40 mg at bedtime or ranitidine 150 mg twice a day. Healing rates were similar in both groups: at four weeks 49% vs 48%, at six weeks 71% vs 69%, and at eight weeks 83% vs 81% for famotidine and for ranitidine, respectively. Pain relief, antacid tablet use, and adverse experiences were also similar in the two groups. Only 25% of patients entered in the gastric ulcer registry were enrolled in the trial. Given that patients with more severe or complicated gastric ulcer disease should be excluded from controlled trials of new drugs, the screening criteria used in the present study be excluded from findings being representative of a quarter of the patients seen in these practices. Therefore, coupling a patient registry with a clinical trial helps determine the applicability of its results. Famotidine 40 mg at bedtime is an effective and well-tolerated treatment of acute, benign gastric ulcer disease and is comparable in efficacy and safety to ranitidine 150 mg twice a day.

Is there a fundic factor which regulates G cells in the antrum?

Both surgical fundusectomy and pharmacologic acid inhibition have been shown to produce antral G cell hyperplasia in rats. Fundusectomy has also been shown to be a reliable, reproducible means to produce hypergastrinemia. In contrast, treatment of animals with famotidine, a histamine H2 receptor antagonist, or omeprazole, a H+-K+-ATPase enzyme inhibitor, failed to produce hypergastrinemia. This suggests that elimination of acid inhibition may not be the sole mechanism of hypergastrinemia after fundusectomy. We hypothesized that removal of the gastric fundus may remove a factor which controls G cell activity.

Stability of intravenous famotidine stored in polyvinyl chloride syringes

The stability of intravenous famotidine in dextrose 5% injection (D5W), NaCl 0.9% injection (NS), and sterile water for injection stored in polyvinyl chloride (PVC) syringes at 4 degrees C for 14 days was studied. The concentration of famotidine samples was determined at time 0, 7 days, and 14 days by reverse-phase high-performance liquid chromatography. Samples were inspected for visual changes and tested for changes in pH. Results of the HPLC analysis indicated that the famotidine samples remained within 94-100 percent and 99-103 percent of the time 0 concentrations at 7 and 14 days, respectively. Repeated measures analysis of variance demonstrated a significant time effect on famotidine concentration as concentrations changed over time (p less than 0.01). This change was small in magnitude, however, and concentrations decreased at 7 days and increased at 14 days. Famotidine is stable at a concentration of 2 mg/mL in D5W, NS, and sterile water for injection stored in PVC syringes at 4 degrees C for 14 days.

Sucralfate in the prevention of porcine experimental peptic ulceration

Sucralfate is the first drug to be shown to prevent ulceration in bile duct-ligated pigs. Usually such ulceration is uniformly fatal. Seven pigs in each of four groups in this study received only saline, or sucralfate (1 g every six hours), famotidine (40 mg per day), or misoprostol (200 micrograms every six hours). A Foley catheter was placed into a gastrectomy after bile duct ligation. Similar groups of sham-operated pigs were also prepared. After 48 hours, all saline-, famotidine-, or misoprostol-treated pigs showed severe macroscopic ulceration, whereas only two of those treated with sucralfate showed minimal macroscopic ulceration. Until now, only highly selective vagotomy has reduced ulceration caused by bile duct ligation. The present results suggest that acid inhibition is not the only important factor in healing bile duct ligation-induced peptic ulceration.

Negative effects of famotidine on cardiac performance assessed by noninvasive hemodynamic measurements

In a randomized placebo-controlled study 12 healthy volunteers were treated for 1 wk each with 10 mg of nifedipine four times daily plus placebo or the same dose of nifedipine concurrently with 40 mg of famotidine once a day. Famotidine did not significantly alter pharmacokinetic parameters of nifedipine. Determination of systolic time intervals showed that the preejection period and the ratio of the preejection period and the left ventricular ejection time were significantly reduced by administration of nifedipine plus placebo. Coadministration of famotidine and nifedipine, however, led to a significant increase of these parameters. In an additional double-blind study, a significant rise of the preejection period and of the ratio was detected after administration of famotidine alone. In impedance cardiography stroke volume and cardiac output were significantly reduced by famotidine. Heart rate and blood pressure values were not altered by the H2-antagonist. For the first time, to our knowledge, the observed changes of hemodynamic parameters appear to indicate that famotidine may exert negative effects on cardiac performance which, in our opinion, could be of clinical relevance in elderly subjects or in patients with heart failure.

A multicenter, randomized, double-blind study comparing once-daily bedtime administration of famotidine and ranitidine in the short-term treatment of active duodenal ulcer

The efficacy and safety of famotidine and ranitidine in the treatment of active duodenal ulcer were compared in a multicenter, randomized double-blind study. The study was carried out at 5 centers and involved a total of 143 patients with endoscopically documented active duodenal ulcer. The patients received either famotidine (1 40 mg tablet at night) or ranitidine 2 150 mg tablets at night). Endoscopic examinations were performed at 4 and 6 weeks of active treatment. Day and nocturnal pain were also monitored, and the laboratory and clinical profiles evaluated. One hundred and thirty-three patients fulfilled the evaluation criteria (66 patients in the famotidine group and 67 in the ranitidine group). Healing rates at weeks 4 or 6 of treatment showed no significant differences between the famotidine group and the ranitidine group. The healing rates were 78% at week 4 and 96% at week 6 in the famotidine group, and 76% at week 4 and 95% at week 6 in the ranitidine group. Similar results were observed in both treatment groups with regard to pain resolution, decrease in antacid intake and safety profile.

[Inhibition of 24-hour acidity by nizatidine]

In a randomized, double-blind, placebo-controlled, comparative cross-over study, we studied the effect of four H2-receptor antagonists on intragastric 24-hour acidity, nocturnal volume and acid output. Ten healthy male volunteers were administered 300 mg or 150 mg nizatidine, 800 mg cimetidine, 300 mg ranitidine, 40 mg famotidine, or placebo on several days, in each case at 9:000 PM. Nocturnal intragastric H+ concentration (mmol/l) (11:00 PM to 7:00 AM) was significantly reduced by all H2 blockers compared with placebo. We obtained the following inhibition rates: Cimetidine 67%; ranitidine 95%; famotidine 89%; nizatidine 80% (300 mg) and 69% (150 mg). Nocturnal acid (mmol/l) and volume output (ml/h) were also significantly (compared with placebo) inhibited by all four H2-receptor antagonists. Inhibition of nocturnal acid secretion was almost identical on nizatidine 300 mg nocte, ranitidine 300 mg nocte, famotidine 40 mg nocte, and cimetidine 800 mg nocte. Nizatidine 300 mg nocte and 150 mg nocte exclusively reduced acid secretion at night, without an aftereffect into the following day (8:00 AM to 6:00 PM). These results suggest that the clinical efficacy of these H2-receptor antagonists is identical with respect to healing peptic ulcer disease and providing freedom from pain. It is generally accepted today that gastric acid inhibitors used in the treatment of peptic ulcer disease should interfere with daytime gastric acid secretion as little as possible, particularly since the acid protects the stomach from bacteria ingested with the food during the day.

[Drugs used in the therapy of peptic ulcer with special reference to H2 receptor blockaders]

Drugs used in the management of peptic ulcer are reviewed with special attention to the possibilities offered by H2 receptor antagonists. In this context, histaminergic transmission and distribution of H2 receptors are briefly reviewed. Among other substances, special interest has been raised by H+ and K+-dependent ATPase inhibitors; the most recently introduced derivatives of these substances which are as yet in the experimental stage, are also listed.

Acute effects of ranitidine, famotidine and omeprazole on plasma gastrin in the rat

In the rat, treatment with gastric inhibitory drugs may result in hypergastrinemia, an effect thought to be in response to increased gastric pH caused by inhibition of acid secretion. This study compared 24-hr profiles of plasma gastrin levels associated with three different compounds at equivalent, highly effective antisecretory doses. Ranitidine, famotidine and omeprazole at 60, 20 and 40 mg/kg p.o., respectively, inhibited basal acid secretion of chronic gastric fistula rats by greater than 95% and raised intraluminal pH to above 7.0 for 5 hr. The peak plasma gastrin levels associated with each agent were observed 5 hr after dosing. Ranitidine, famotidine and omeprazole induced statistically significant and distinct peak hypergastrinemic responses of 312 +/- 20, 483 +/- 28 and 616 +/- 27 pg/ml, respectively. After 8 hr ranitidine and famotidine associated gastrin values returned to control levels, whereas those of omeprazole remained substantially above control values until the 12th hr. Differences in peak gastrin levels between compounds disappeared at increased dose levels of 500 mg/kg for ranitidine, 200 or 2000 mg/kg for famotidine and 140 mg/kg for omeprazole. Unlike high dose famotidine, omeprazole (140 mg/kg) maintained peak plasma gastrin levels at 8, 12, and 16 hr after dosing. These studies demonstrate clearly hypergastrinemic responses to single dose administration of ranitidine, famotidine and omeprazole. The differences observed in peak plasma gastrin levels at equivalent antisecretory doses of these agents suggests the presence of luminal acid independent components that effect gastrin release. Moreover, these studies indicate that, in the rat, the most unique aspect of omeprazole-associated hypergastrinemia is the magnitude of its prolonged response.

The effects of cimetidine, ranitidine and famotidine on rat hepatic microsomal cytochrome P-450 activities

It has been questioned whether the interaction of H2-antagonists with cytochrome P-450 that is observed in vitro is also relevant for the in vivo situation. Until now the possibility that cytochrome P-450 may function with different modes of action has been neglected in this respect. We studied the effect of cimetidine, ranitidine and famotidine on the monoxygenase, the oxidase and the peroxidase action of cytochrome P-450. Biotransformation catalyzed by the monoxygenase and oxidase action of cytochrome P-450 was affected by cimetidine (probably via its ligand interaction with cytochrome P-450), whereas metabolism by the peroxidase mode of action of cytochrome P-450 was hardly influenced. Ranitidine and famotidine (both pharmacodynamically more potent than cimetidine) only slightly affected cytochrome P-450 activities.

A single nocte dose of famotidine in the treatment of duodenal ulcer

Fifty three patients with duodenal ulcer were treated with 40 mg of famotidine at bed time. Repeat endoscopy showed healing rates of 69.8% and 83% at 4 and 6 weeks respectively. Seven patients were kept on a maintenance dose of 20 mg nocte for one year, of these one had a relapse despite taking the drug regularly. No appreciable side effects were observed with the drug (JPMA 39:104, 1989).

Comparison of the effects of famotidine and ranitidine on gastric secretion in patients undergoing elective surgery

A randomised double-blind comparison of oral famotidine and ranitidine given 2 hours before induction, on gastric secretion (volume and pH) was carried out on 93 patients undergoing elective surgery. Gastric contents were aspirated immediately after tracheal intubation. Famotidine significantly reduced the gastric volume, compared with the other groups, including ranitidine. Both famotidine and ranitidine significantly elevated gastric pH towards neutral, compared with the other groups. There was no significant difference between ranitidine and famotidine in respect of the pH. The patients premedicated with famotidine and ranitidine were well protected against Mendelson's syndrome, whereas 38% of patients from the other groups remained at risk.

[Famotidine in the short and long term treatment of duodenal ulcer: clinical and physiopathologic study]

The aim of this study was to evaluate the clinical efficacy of short and long-term treatment with famotidine 40 mg/daily at bed time in duodenal ulcer disease. 45 patients with endoscopically proven active duodenal ulcer undertaken the study. Endoscopic evaluations were performed at 6 weeks, 3 and 6 months from the start of the study. The following parameters were evaluated: pepsinogen group I and gastrin levels in serum, pH, acid and neutral glycoprotein, N-acetylneuraminic acid, pepsin in gastric juice collected during the upper gastrointestinal endoscopy. 6 weeks healing rate was 91.1%. After the third month of follow-up 14.2% of the patients presented an endoscopical proven episode of relapse. No relapses were observed at the end of the study (after 6 months of treatment). Acid glycoprotein, N- acetylneuraminic acid and pepsin concentrations significantly decreased after 6 weeks of treatment (p less than 0.0125, p less than 0.025, p less than 0.005 respectively), while serum levels of pepsinogen group I, gastrin and gastric pH increased (p less than 0.0005, p less than 0.005, p less than 0.025). After 6 months period of therapy, a significant increase of neutral glycoproteins (p less than 0.01) and a decrease of pepsin (p less than 0.005) and acid glycoproteins (p less than 0.01) was observed. On the contrary, gastric N- acetylneuraminic acid, pH, serum gastrin and pepsinogen group I presented the pre-trial values.

IN CONCLUSION

1) famotidine appears to be an effective and safe therapy for duodenal ulcer treatment; 2) it seems to act not only by inhibiting gastric acid secretion but also influencing some parameters related to the gastric mucosal barrier.

Neuronal histamine modulates feeding behavior through H1-receptor in rat hypothalamus

To clarify the physiological role of hypothalamic neuronal histamine in control of food intake, ingestive behavior and neuronal activity were investigated under blockade or diurnal fluctuation of hypothalamic neuronal histamine. Histamine H1- but not H2-receptor antagonist potently induced feeding in a dose-related manner after infusion into rat third cerebroventricle at 1100 h. Elicitation was attenuated after infusion at 1940 h when histamine content in the hypothalamus was low and was abolished after intraperitoneal pretreatment with 0.11 mmol alpha-fluoromethylhistidine (alpha-FMH), a specific suicide inhibitor of histidine decarboxylase. Electrophoretic application of a histamine H1-receptor antagonist to ventromedial hypothalamic neurons specifically suppressed activities of glucose-responding neurons that are related to food intake. The suppressive effect was also attenuated by intraperitoneal pretreatment with alpha-FMH. These results suggest that feeding induced by histamine H1-receptor antagonists is due to blockade of neuronal histamine at the site of histamine H1-receptors, at least in part, in the ventromedial hypothalamus and that diurnal fluctuation of feeding behavior may reflect circadian variation of neuronal histamine level.

Beneficial effects of glucose polymer and an H2-receptor blocker in a patient with a proximal ileostomy

A patient with an ileocolectomy and proximal ileostomy for Crohn's disease had severe diarrhea and steatorrhea. An oral electrolyte solution containing glucose polymer was shown to improve water and electrolyte absorption. Ileal contents were abnormally acidic. Therapy with an H2-receptor blocker raised ileal pH, improved the efficiency of fat absorption, and promoted a gain in body weight.

Pharmacological control of the human gastric histamine H2 receptor by famotidine: comparison with H1, H2 and H3 receptor agonists and antagonists

Histamine 0.1 microM-0.1 mM increased adenylate cyclase activity five- to ten-fold in human fundic membranes, with a potency Ka = 3 microM. The histamine dose-response curve was mimicked by the H3 receptor agonist (R) alpha-MeHA, but at 100 times lower potency, Ka = 0.3 mM. Histamine-induced adenylate cyclase activation was abolished by H2, H1 and H3 receptor antagonists, according to the following order of potency IC50: famotidine (0.3 microM) greater than triprolidine (0.1 mM) thioperamide (2 mM), respectively. Famotidine has no action on membrane components activating the adenylate cyclase system, including the Gs subunit of the enzyme stimulated by forskolin and cell surface receptors sensitive to isoproterenol (beta 2-type), PGE2 and VIP. The Schild plot was linear for famotidine (P less than 0.01) with a regression coefficient r = 0.678. The slope of the regression line was 0.64 and differs from unity. Accordingly, famotidine showed a slow onset of inhibition and dissociation from the H2 receptor in human cancerous HGT-1 cells. The results demonstrate that famotidine is a potent and selective H2 receptor antagonist with uncompetitive actions in human gastric mucosa. Consequently, famotidine might be a suitable drug with long-lasting actions in the treatment of Zollinger-Ellison syndrome. The results also confirm and extend the previous observations that (R) alpha-MeHA and thioperamide are two selective ligands at histamine H3 receptor sites. In the human gastric mucosa, these drugs are respectively 330 and 6700 times less potent than histamine and famotidine on the adenylate cyclase system. The possible involvement of histamine H3 receptors in the regulation of gastric secretion is proposed.

Refractory duodenal ulcers (nonhealing duodenal ulcers with standard doses of antisecretory medication)

To evaluate possible differences between patients with refractory duodenal ulcers and those with duodenal ulcers that respond to standard doses of antisecretory medications, we determined basal acid outputs by nasogastric suction and daily smoking histories in 75 patients with endoscopically documented active duodenal ulcers. Patients were treated for at least eight weeks with standard doses of antisecretory medications and endoscopic healing or nonhealing was documented. Fifty-five patients that had complete healing of their duodenal ulcers had a mean basal acid output of 6.6 +/- 5.3 meq/hr, and 18/55 had daily cigarette smoking histories, whereas 20 patients that had nonhealing duodenal ulcers had a mean basal acid output of 20.0 +/- 9.6 meq/hr, and 8/20 had daily cigarette smoking histories. There were no significant differences between the two groups with regard to age, duodenal ulcer size, or cigarette smoking history. However, there were significant differences in male-female ratio (P less than 0.02) and in mean basal acid output (P less than 0.001), and all patients with nonhealing duodenal ulcers had basal acid outputs of greater than 10.0 meq/hr. Patients with nonhealing duodenal ulcers were treated with increased doses of ranitidine, mean 675 mg/day (range 600-1200 mg/day), and all had complete healing endoscopically documented. These results indicate that patients treated with standard doses of antisecretory medications with nonhealing duodenal ulcers have increased basal acid outputs of greater than 10.0 meq/hr, and the duodenal ulcers heal with increased doses of antisecretory medication.

Stability of famotidine in minibags refrigerated and/or frozen

The stability of famotidine 200 micrograms/ml in dextrose 5% injection (D5W) and in NaCl 0.9% (NS) solution in polyvinyl chloride (PVC) minibags was studied when these solutions were stored refrigerated at 4 degrees C for 14 days, or frozen at -20 degrees C for 28 days and then refrigerated for 14 days. Famotidine concentration was determined in the refrigerated samples immediately after compounding (time 0) and also on days 2, 4, 8, and 14 by high-performance liquid chromatography (HPLC). Famotidine concentration was determined by HPLC in frozen samples at time 0 and days 7, 14, 21, 28, 35, and 42. Solutions were also observed for visual changes and pH was tested at these time intervals. Results of the HPLC famotidine analysis demonstrated 94-107 percent recovery of famotidine in D5W and NS at 14 days in refrigerated samples and 98-100 percent recovery of famotidine in minibags frozen for 28 days then refrigerated for 14 days. Analysis of variance showed no time effect on the concentration of famotidine in refrigerated samples (p = 0.741). Linear regression of the frozen minibag data indicated no time effect. Famotidine 200 micrograms/ml is stable in dextrose 5% injection and NaCl 0.9% injection when stored in PVC bags at 4 degrees C for 14 days, or when frozen for 28 days and then subsequently refrigerated for 14 days.

Comparison of the effects of placebo, ranitidine, famotidine and nizatidine on intragastric acidity by means of continuous pH recording

The effects of single daily doses of placebo, nizatidine 300 mg, ranitidine 300 mg and famotidine 40 mg, given at 22.00 h, have been compared in 16 patients with healed duodenal ulcers. Each of them underwent the above treatment on four separate occasions. The three H2 receptor antagonists showed a significantly higher acid inhibition than placebo (p less than 0.003) throughout the whole 24-hour period. Famotidine turned out to be more effective than nizatidine (p less than 0.02) in reducing circadian acidity, while there was no difference between ranitidine and nizatidine. The effects of the three H2 blockers on overnight acidity (from 23.00 to 07.00) were similar to each other, whereas both famotidine (p less than 0.003) and ranitidine (p less than 0.02) produced more anacidity than nizatidine during the morning hours (from 07.00 to 12.00). The time period elapsed in consecutive minutes above 5.0 pH units during drug-related events was significantly longer with both famotidine (p less than 0.01) and ranitidine (p less than 0.01) compared to nizatidine. Therefore in the recommended dosages for clinical use the acid suppression of nizatidine was significantly shorter-lasting than that of both ranitidine and famotidine. The major change is represented by the lack of carryover effect of nizatidine on morning acidity.

(Multicenter study)]

A multicentric open study designed to evaluate the effect of famotidine in the treatment of gastric ulcer was performed in several institutions located in 15 different cities of Mexico. 54 patients with gastric ulcer demonstrated by endoscopy were given 40 mg of famotidine daily, administered as a single dose at night. After 6 and 8 weeks of treatment, healing of the ulcer was observed in 63% and 88.9%, respectively. Side-effects were very unusual.

A multicenter, randomized, double-blind study comparing famotidine with cimetidine in the treatment of active duodenal ulcer disease

The efficacy and safety of famotidine (40 mg at night), a new potent H2-receptor antagonist, has been studied in 119 patients by four investigators in four Spanish hospitals in a randomized double-blind comparative study with cimetidine (800 mg at night). Antacid tablets were allowed as additional treatment, if needed for pain relief. There were no significant differences between the groups in baseline characteristics, including duodenal ulcer size. Efficacy parameters included daytime and nocturnal symptom relief and duodenal ulcer healing, documented by endoscopy, and defined as complete reepithelization of the ulcer crater. Endoscopy was performed at baseline and after 4 and 6 weeks of treatment. One hundred and five patients fulfilled the evaluation criteria (51 patients in the famotidine group and 54 in the cimetidine group). After 4 weeks, in 91.6% of the patients receiving famotidine and 82.3% of the patients receiving cimetidine ulcers were healed. After 6 weeks, healing rates were 96% (famotidine) and 85.1% (cimetidine) (p = 0.056). Pain relief was rapid in both treatment groups, with a tendency to better response during the day in the famotidine group. The intake of antacids, as well as the clinical and laboratory safety profile were similar for both groups.