Malignant mixed germ cell tumor of ovary presenting as advanced disease in an adolescent girl

Mixed germ cell tumors are very rare in young females. Patient survival, preservation of ovarian function and fertility are becoming an important issue. A locally advanced (III), bulky malignant mixed germ cell tumour in a 12-year-old girl presented to the Department of Radiotherapy, Regional Institute of Medical Sciences, Imphal, Manipur, in January 2011 with abdominal distension for one month. On physical examination, there was a large lower abdominal mass approximately 16x 14 cm2. Abdominal and pelvic CTs showed a lobulated 19x 15x10 cm soft tissue attenuation mass lesion in the pelvis extending superoanteriorly to supra-umbilical area. Laboratory investigations revealed increased serum LDH (4,245 IU/ L) and serum P-hCG (105.4 mIU/ml). Ultrasonography (USG)-guided fine needle aspiration cytology (FNAC) from left ovarian mass was suggestive of malignant germ cell tumour. In view of bulky and advanced stage, patient was administered four cycles of neoadjuvant chemotherapy (inj. ifosphamide 1,440 mg, inj. etoposide 90 mg, inj. cisplatin 24 mg for D1 -5, four weekly) followed by left salpingo-oophorectomy with wedge biopsy of right ovary and partial omentectomy, and another two cycles of adjuvant chemotherapy with same regimen. Biopsy tissue histopathology report also confirmed mixed germ cell tumour. Patient was kept on regular follow-up and she has been disease-free for the last four years. The present authors' treatment policy in such bulky and advanced tumor in adolescents is effective.

Dietary polyphenols for treatment of Alzheimer's disease--future research and development

Polyphenols are the most abundant components of our daily food, occupying the major portion of naturally occurring phytochemicals in plants. Currently, polyphenols have received a special attention from the scientific community against health risk because of their antioxidant capacity and the ability to scavenge the free radicals formed during the pathological process like cancer, cardiovascular diseases and neurodegenerative disorders. Alzheimer's disease, one of the common forms of dementia is an intricate, multifactorial mental illness which is characterized by age-dependent memory loss ultimately leading to a steady decline of cognitive function. Extracellular amyloid beta deposition and intracellular tau hyperphosphorylation are the two main alterations occurring in the cells reported to cause neuronal dysfunction during AD. Dietary intake of polyphenols is known to attenuate the progression of the disease by showing strong potential to tackle the alterations and reduce the risk of AD by reversing the cognitive deficits. A large number of polyphenolic compounds showing promising results against AD pathologies have been identified and described in the past decade. Many efforts have been made to unravel the molecular mechanisms and the specific interactions of polyphenols with their targets in the pathway. This review focuses on the therapeutic potential and promising role of dietary polyphenols as nutraceuticals to combat AD.

In vitro antioxidant and anti-cholinesterase activities of Rhizophora mucronata

CONTEXT

Rhizophora mucronata Lam. (Rhizophoraceae), commonly known as Asiatic mangrove, has been used traditionally among Asian countries as folk medicine.

OBJECTIVE

This study investigates the cholinesterase inhibitory potential and antioxidant activities of R. mucronata.

MATERIALS AND METHOD

Rhizophora mucronata leaves were successively extracted using solvents of varying polarity and a dosage of 100-500 µg/ml were used for each assay. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities were assessed according to the method of Ellman. In vitro antioxidant activity was assessed using free radical scavenging, reducing power, and metal-chelating activity (duration - 3 months). Total phenolic and flavonoid content were quantified spectrophotometrically. Compound characterization was done using column chromatography, NMR, FTIR, and LC-MS analysis.

RESULTS

Methanolic leaf extract (500 µg/ml) exhibited the highest inhibitory activity against AChE (92.73 ± 0.54%) and BuChE (98.98 ± 0.17%), with an IC50 value of 59.31 ± 0.35 and 51.72 ± 0.33 µg/ml, respectively. Among the different solvent extracts, methanolic extract exhibited the highest antioxidant activity with an IC50 value of 47.39 ± 0.43, 401.45 ± 18.52, 80.23 ± 0.70, and 316.47 ± 3.56 µg/ml for DPPH, hydroxyl, nitric oxide radical, and hydrogen peroxide, respectively. Total polyphenolic and flavonoid contents in methanolic extract were observed to be 598.13 ± 1.85 µg of gallic acid equivalent and 48.85 ± 0.70 μg of rutin equivalent/mg of extract. Compound characterization illustrated (+)-catechin as the bioactive compound responsible for cholinesterase inhibitory and antioxidant activities.

CONCLUSION

The presence of rich source of flavonoids, in particular catechin, might be responsible for its cholinesterase inhibitory and antioxidant activities.

Silymarin prevents the toxicity induced by benzo(a)pyrene in human erythrocytes by preserving its membrane integrity: an in vitro study

Silymarin, the purified extract from milk thistle Silybum marianum (L.) Gaertn, consists mainly of four isomeric flavonolignans: silibinin, isosilibinin, silidianin, and silichristin. The present study was carried out to evaluate the protective potential of silymarin in human erythrocytes against in vitro exposure to the carcinogen benzo(a)pyrene (B(a)P). Erythrocytes isolated from human blood were divided into four groups and treated with Vehicle [Group I], B(a)P (300 μM) [Group II], Silymarin (500 μM) + B(a)P (300 μM) [Group III], and Silymarin alone (500 μM)] [Group IV]. Silymarin treatment maintains the integrity of erythrocytes by preventing hemolysis, protein thiol oxidation and by decreasing the activity of AChE. SEM observations indicate that B(a)P induced significant alteration in the morphology of erythrocytes to echinocytes, which may be due to the interaction of B(a)P with the membrane's outer phopholipid monolayer. The light microscopic and SEM images show that silymarin treatment maintains the normal discocytic morphology of erythrocytes. The protective effect of silymarin might be attributed to its chemical structure and membranotrophic nature. The components silibinin, silydianin, and silychristin have OH in the 3rd, 5th, and 7th carbon atoms that may account for its increased antioxidant activity and removal of ROS formed during B(a)P metabolism.

Eugenol alters the integrity of cell membrane and acts against the nosocomial pathogen Proteus mirabilis

Eugenol, a member of the phenylpropanoids class of chemical compounds, is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, and bay leaf. The antibacterial activity of eugenol and its mechanism of bactericidal action against Proteus mirabilis were evaluated. Treatment with eugenol at their minimum inhibitory concentration [0.125 % (v/v)] and minimum bactericidal concentration [0.25 % (v/v)] reduced the viability and resulted in complete inhibition of P. mirabilis. A strong bactericidal effect on P. mirabilis was also evident, as eugenol inactivated the bacterial population within 30 min exposure. Chemo-attractant property and the observance of highest antibacterial activity at alkaline pH suggest that eugenol can work more effectively when given in vivo. Eugenol inhibits the virulence factors produced by P. mirabilis as observed by swimming motility, swarming behavior and urease activity. It interacts with cellular membrane of P. mirabilis and makes it highly permeable, forming nonspecific pores on plasma membrane, which in turn directs the release of 260 nm absorbing materials and uptake of more crystal violet from the medium into the cells. SDS-polyacrylamide gel, scanning electron microscopy and Fourier transform infrared analysis further proves the disruptive action of eugenol on the plasma membrane of P. mirabilis. The findings reveal that eugenol shows an excellent bactericidal activity against P. mirabilis by altering the integrity of cell membrane.

Silymarin prevents benzo(a)pyrene-induced toxicity in Wistar rats by modulating xenobiotic-metabolizing enzymes

Benzo(a)pyrene (B(a)P), which is commonly used as an indicator species for polycyclic aromatic hydrocarbon (PAH) contamination, has a large number of hazardous consequences on human health. In the presence of the enzyme cytochrome-P-450 1A1 (CYP1A1), it undergoes metabolic activation to form reactive intermediates that are capable of inducing mutagenic, cytotoxic, teratogenic and carcinogenic effects in various species and tissues. Research within the last few years has shown that flavonoids exhibit chemopreventive effect against these toxins. In the present study, the protective effect of silymarin (a flavonoid) against B(a)P-induced toxicity was monitored in Wistar rats by evaluating the levels of hepatic phase I (CYP1A1), phase II enzymes (glutathione-S-transferase, epoxide hydroxylases, uridinediphosphate glucuronosyltransferases, NAD(P)H: quinone oxidoreductase 1, sulfotransferases), cellular antioxidant enzyme heme oxygenase and total glutathione. The results reveal that silymarin possesses substantial protective effect against B(a)P-induced damages by inhibiting phase I detoxification enzyme CYP1A1 and modulating phase II conjugating enzymes, which were confirmed by histopathological analysis. Overall, the inhibition of CYP1A1 and the modulation of phase II enzymes may provide, in part, the molecular basis for the effect of silymarin against B(a)P.

CYP1A1 gene polymorphisms: lack of association with breast cancer susceptibility in the southern region (Madurai) of India

The cytochrome P 450 1A1 gene encoding a phase I metabolic enzyme appears to be a candidate for breast cancer risk. It is involved in the phase I detoxification of polycyclic aromatic hydrocarbons (PAHs) and 2-hydroxylation of estrogens and mammary carcinogens into 2-hydroxy catechol metabolites. Several studies have investigated polymorphisms in CYP1A1 and breast cancer risk with inconsistent results. We here carried out a population based case-control study of the CYP MspI (CYP1A1*1/M1) and Ile462Val (CYP1A1*2/M2) polymorphisms in CYP1A1 to clarify their importance in determining breast cancer susceptibility in a South Indian population. A total of 50 cases and 50 controls were genotyped for both polymorphisms. We also investigated putative interactions with exposure to pollution, radiation and intake of tobacco and CYP1A1 genotype and breast cancer risk using a case only study design. The genotype distribution of CYP1A1*1 in cancer patients was 6% for homozygous (CYP1A1 M1 [C/C], 34% for heterozygous CYP1A1 M1 [T/C] and 60% for wild type (CYP1A1 M1 [T/T] (OR: 0.583, CI-95% (0.252-1.348). The genotype distribution of M2 genotypes in patients was 24% of homozygous (CYP1A1 M2 [Val/Val], 4% for heterozygous (CYP1A1 M2 [Ile/Val] and 72% for wild type allele (CYP1A1 M2 [Ile/Ile] [OR: 0.720, CI-95% (0.606-0.856)]. Our results suggest that there is no significant correlation between CYP1A1 M1/ CYP1A1 M2 polymorphism and occurrence of breast cancer in South Indian women.

Eugenol (an essential oil of clove) acts as an antibacterial agent against Salmonella typhi by disrupting the cellular membrane

AIM OF THE STUDY

To evaluate the antibacterial activity of eugenol and its mechanism of bactericidal action against Salmonella typhi.

MATERIALS AND METHODS

The antibacterial activity was checked by disc-diffusion method, MIC, MBC, time course assay and pH sensitivity assay. The chemo-attractant property of eugenol was verified by chemotaxis assay. The mode of action of eugenol was determined by crystal violet assay, measurement of release of 260 nm absorbing material, SDS-PAGE, FT-IR spectroscopy, AFM and SEM.

RESULTS

Treatment with eugenol at their MIC (0.0125%) and MBC (0.025%) reduced the viability and resulted in complete inhibition of the organism. Eugenol inactivated Salmonella typhi within 60 min exposure. The chemo-attractant property of eugenol combined with the observed high antibacterial activity at alkaline pH favors the fact that the compound can work more efficiently when given in vivo. Eugenol increased the permeability of the membrane, as evidenced by crystal violet assay. The measurement of release of 260 nm absorbing intracellular materials, SDS-PAGE, SEM and AFM analysis confirmed the disruptive action of eugenol on cytoplasmic membrane. The deformation of macromolecules in the membrane, upon treatment with eugenol was verified by FT-IR spectroscopy.

CONCLUSION

The results suggest that the antibacterial activity of eugenol against Salmonella typhi is due to the interaction of eugenol on bacterial cell membrane.

Silymarin protects PBMC against B(a)P induced toxicity by replenishing redox status and modulating glutathione metabolizing enzymes--an in vitro study

PAHs are a ubiquitous class of environmental contaminants that have a large number of hazardous consequences on human health. An important prototype of PAHs, B(a)P, is notable for being the first chemical carcinogen to be discovered and the one classified by EPA as a probable human carcinogen. It undergoes metabolic activation to QD, which generate ROS by redox cycling system in the body and oxidatively damage the macromolecules. Hence, a variety of antioxidants have been tested as possible protectors against B(a)P toxicity. Silymarin is one such compound, which has high human acceptance, used clinically and consumed as dietary supplement around the world for its strong anti-oxidant efficacy. Silymarin was employed as an alternative approach for treating B(a)P induced damage and oxidative stress in PBMC, with an emphasis to provide the molecular basis for the effect of silymarin against B(a)P induced toxicity. PBMC cells exposed to either benzopyrene (1 microM) or silymarin (2.4 mg/ml) or both was monitored for toxicity by assessing LPO, PO, redox status (GSH/GSSG ratio), glutathione metabolizing enzymes GR and GPx and antioxidant enzymes CAT and SOD. This study also investigated the protective effect of silymarin against B(a)P induced biochemical alteration at the molecular level by FT-IR spectroscopy. Our findings were quite striking that silymarin possesses substantial protective effect against B(a)P induced oxidative stress and biochemical changes by restoring redox status, modulating glutathione metabolizing enzymes, hindering the formation of protein oxidation products, inhibiting LPO and further reducing ROS mediated damages by changing the level of antioxidant enzymes. The results suggest that silymarin exhibits multiple protections and it should be considered as a potential protective agent for environmental contaminant induced immunotoxicity.

Study of p53 codon 72 polymorphism and codon 249 mutations in Southern India in relation to age, alcohol drinking and smoking habits

Germline polymorphisms of genes involved in different steps of tumorigenesis like p53, the tumor suppressor gene, are reported to determine the individual susceptibility to cancer. Lung cancer is one of the most common and lethal cancers and tobacco smoking remains its most important etiologic factors. The most frequently p53 mutated codons of lung cancer are 72 (exon 4) and 249 (exon 7). Since mutations in the p53 gene are present in ∼40% of all human lung cancers and are more common in smokers than in nonsmokers, we aimed to detect the status of p53 at codon 72 for Arg/Arg or Arg/Pro or Pro/Pro allele polymorphism and p53 codon 249 mutation in smokers and nonsmokers of South India. Allele frequencies in the nonsmokers were 0.16 for the Arg/Pro allele and 0.84 for the Pro/Pro allele in our study population. Among the smokers, the frequencies of the Arg/Pro, Arg/Arg, and Pro/Pro alleles were 0.88, 0.04, and 0.08, respectively. No mutation was detected in both smokers and nonsmokers in p53 codon 249. From the worldwide scenario, it can be speculated that the smokers, with Arg/Pro genotype are more prone for lung cancer or to other types of cancer.

Protective effect of silymarin on erythrocyte haemolysate against benzo(a)pyrene and exogenous reactive oxygen species (H2O2) induced oxidative stress

The present study was carried out to evaluate the in vitro antioxidant properties and protective effects of silymarin (milk thistle) in human erythrocyte haemolysates against benzo(a)pyrene [B(a)P], a potent carcinogenic chemical. Protective effect of silymarin was assessed in vitro by monitoring the antioxidant enzymes and malondialdehyde in three groups of haemolysates-(I) vehicle control (II) B(a)P incubated group and (III) B(a)P co incubated with silymarin. The effects of silymarin on lipid peroxidation (LPO) and antioxidant enzymes [superoxide dismutase; SOD, catalase; CAT, glutathione peroxidase; GPx, glutathione reductase; GR and glutathione-S-transferases; GST] were assessed on haemolysates. It was observed that specific activity of antioxidant enzymes were significantly decreased and the malondialdehyde levels were elevated when haemolysates were incubated with B(a)P. The protective effect of silymarin is elucidated by the significant reversal of the antioxidant enzymes and reduction in the levels of malondialdehyde. In addition, haemolysates were incubated with B(a)P for 45 min and the B(a)P metabolite, 3-hydroxy benzo(a)pyrene (3-OH-B(a)P) was detected using HPLC. An increased level of the metabolite was detected in group II. Whereas, when haemolysates were co-incubated with silymarin, the reactive metabolite 3-OH-B(a)P was not detectable which further confirms the protective role of silymarin. Generation of 3-OH-B(a)P in group II implicates the possibility of reactive oxygen species (O2- and H2O2) production in haemolysates during cytochrome P4501A1 (CYP1A1) mediated Phase-I-metabolism. Hence, we incubated the haemolysates with exogenous reactive oxygen species H2O2 and assessed the protective role of silymarin against H2O2. From the results of our study, it was suggested that silymarin possess substantial protective effect and free radical scavenging mechanism against environmental contaminants induced oxidative stress damages.

Silymarin Protection against Major Reactive Oxygen Species Released by Environmental Toxins: Exogenous H2O2Exposure in Erythrocytes

Silymarin is a polyphenolic plant flavonoid (a mixture of flavonoid isomers such as silibinin, isosilibinin, silidianin and silichristin) derived from Silymarin marianum that has anti-inflammatory, hepatoprotective and anticarcinogenic effects. Our earlier studies have shown that silymarin plays a protective role against the oxidative damage induced by environmental contaminants like benzo(a)pyrene in erythrocyte haemolysates. During the detoxification of these environmental contaminants, the major reactive oxygen species generated is hydrogen peroxide (H(2)O(2)). Because H(2)O(2 )can easily penetrate into the cell and cause damage to biomolecules, the protective role of silymarin was further assessed against this cytotoxic agent in vitro in erythrocyte haemolysates. The protective effect was monitored by assessing the levels of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-s-transferase, glutathione peroxidase and malondialdehyde (LPO) in three groups: vehicle control, H(2)O(2)-exposed groups and drug co-incubation group (H(2)O(2) + silymarin). The protective effect of silymarin on the non-enzymic antioxidant glutathione and haemolysis, methaemoglobin content and protein carbonyl content were also assessed. It was observed that the activities of antioxidant enzymes and glutathione were reduced and the malondialdehyde levels were elevated after H(2)O(2 )exposure. There were also alterations in haemolysis, methaemoglobin content and protein carbonyl content, whereas after the administration of silymarin, the antioxidant enzyme activities reversed to near normal with reduced malondialdehyde content and normalized haemolysis, methaemoglobin content and protein carbonyl content. The results suggest that silymarin possesses substantial protective effect and free radical scavenging mechanism against exogenous H(2)O(2)-induced oxidative stress damages, hence, can be used as a protective drug against toxicity induced by environmental contaminants.

Protective effect of Premna tomentosa extract (L. verbanacae) on acetaminophen-induced mitochondrial dysfunction in rats

Allurement of herbs as health beneficial foods (physiologically functional foods) and as a source material for the development of new drugs, has led to greater furtherance in the study of herbal medicines during recent years. Plant extracts are being utilized to treat a wide variety of diseases like hepatotoxicity. Premna tomentosa is one such medicinal plant used widely in Indian ayurvedic medicine for the treatment of liver disorders. This study appraised the effectiveness of P. tomentosa leaf extract in protecting the liver against mitochondrial damage induced by acetaminophen, since mitochondrial injury has been investigated as a potential initiator of hepatotoxicity. Normal Wistar strain rats were pre-treated with P. tomentosa extract (750 mg/kg, orally) for 15 days and then intoxicated with acetaminophen (640 mg/kg, orally). Mitochondria were isolated from liver of experimental animals and assessed for the levels of lipid peroxide products, GSH and mitochondrial enzymes (isocitrate dehydrogenase, alpha-keto glutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, NADH dehydrogenase and cytochrome-C-oxidase). The levels of Lipid peroxidation products were increased and the levels of the other assessed parameters were significantly decreased in hepatotoxicity induced animals. Whereas, the levels were brought back to normal in P. tomentosa pre-treated rats, which shows the protective effect of the extract against mitochondrial damage. Presence of anti-oxidant compound D-limonene (58%) in P. tomentosa leaves, which is known to enhance conjugation of toxic metabolites by maintaining liver GSH concentrations may explain the hepatoprotective property of the extract.

Protective effect of Premna tomentosa (L. Verbenaceae) extract on membrane-bound phosphatases and inorganic cations transport in acetaminophen-induced hepatotoxicity rats

Hepatic injury elicits intracellular stress that leads to peroxidation of membrane lipids accompanied by alteration of structural and functional characteristics of membrane, which affect the activities of membrane-bound ATPases. The present study appraised the membrane protective effect of Premna tomentosa, a hepatoprotective drug used in Indian traditional medicine. Wistar strain rats were pre-treated with Premna tomentosa extract (750 mg/kg, orally) for 15 days, 24 h prior to administration of acetaminophen (640 mg/kg, orally). During acetaminophen intoxication, the levels of membrane-bound enzymes were significantly decreased, total ATPase (1.63-fold), Mg(2+)ATPase (1.9-fold), Ca(2+)ATPase (1.33-fold) and Na(+)K(+)ATPase (1.73-fold) which was accompanied by changes in the levels of inorganic cations N+, K+ and Ca2+. These alterations were prevented by Premna tomentosa extract pre-treatment, which shows that Premna tomentosa supplementation could exert a beneficial effect against liver injury-induced membrane damage. The potential of the plant might be credited to the presence of antioxidant compound limonene in the plant.

Antinociceptive and hypnotic effects of Premna tomentosa L. (Verbenaceae) in experimental animals

Medicinal plants are believed to be an important source of new chemical substances with potential therapeutic effects. The research into plants with alleged folklore use as pain relievers should therefore be viewed as a fruitful and logical research strategy in the search of new analgesic drugs. In the present inquiry, antinociceptive effects of Premna tomentosa (PT) leaf extract (in methanol) were explored in experimental animals by acetic acid-induced writhing, tail flick and tail clip tests. Oral administration of PT extract at different doses (100, 200, 400 and 500 mg/kg) led to significant antinociceptive effects. The extract was also tested for hypnotic effects. Treatment with extracts at different doses (100, 200, 400 and 500 mg/kg) decreased the locomotor activity and potentiated the pentobarbitone-induced sleep time. The responses were dose-dependent. On the basis of the present finding, we can conclude that PT possesses antinociceptive and hypnotic activities.

Immunomodulatory effects of Premna tomentosa extract against Cr (VI) induced toxicity in splenic lymphocytes--an in vitro study

Premna tomentosa (L. Verbanacae) is a widely used medicinal plant. Our earlier studies show that the extract of P. tomentosa leaves prevents acetaminophen-induced hepatotoxicity owing to its antioxidant property. In the present study, we have investigated the immunomodulatory effects of P. tomentosa extract against Chromium (VI) induced immunosuppression in splenic lymphocytes. Chromium (Cr) addition at a concentration of 5 microg showed an increase in cytotoxicity, apoptosis and reactive oxygen species (ROS) and a decrease in lymphocyte proliferation and antioxidant levels, whereas pre-treatment of the cells with P. tomentosa extract (at 500 microg concentration) resulted in decreased cytotoxicity and ROS levels. Further, the drug treatment also maintained antioxidant levels and restored lymphocyte proliferation similar to that of control cells. The results indicated that the leaf extract of P. tomentosa has cytoprotective and immunomodulatory activities.

Similar effect of oxidation deficiency (debrisoquine polymorphism) and quinidine on the apparent volume of distribution of (+/-)-metoprolol

The influence of phenotype (debrisoquine type of oxidation polymorphism) and quinidine on (+/-)-metoprolol distribution parameters was investigated in 7 young male volunteers (4 extensive and 3 poor metabolisers). (+/-)-Metoprolol tartrate 20 mg was administered as a 20 min infusion i) alone, ii) 12 h after an oral 50 mg quinidine sulphate capsule, and iii) on the last day of 3 days of treatment with 250 mg quinidine sulphate b.d. as a slow-release tablet. No stereoselectivity was apparent in either poor or extensive metabolizers. When (+/-)-metoprolol was administered alone the apparent volume of distribution at steady-state (Vss) was higher in extensive than in poor metabolisers (4.84 vs 2.83 l.kg-1, respectively). Pre-treatment with low or multiple high doses of quinidine decreased Vss in extensive metabolisers to values comparable to those in poor metabolisers (3.50 and 3.18 l.kg-1, respectively), but had no significant effect in poor metabolisers (3.24 and 3.42 l.kg-1, respectively). Estimation of Vss by noncompartmental analysis or assuming elimination exclusively from the peripheral compartment yielded similar, although somewhat higher, estimates. Despite the small number of subjects, (+/-)-metoprolol distribution appeared to be different both in genetically and environmentally (quinidine)-determined poor metabolisers, and quinidine inhibition was a good, reversible in vivo model of the genetic deficiency in handling (+/-)-metoprolol. Differences both in first pass pulmonary elimination or in tissue binding are logically consistent with these observations, but the amplitude of the effect exceeds expectations from available biological evidence on selective pulmonary metabolic activity and on specific tissue binding sites.

Zero-order release formulation of oxprenolol hydrochloride with swelling and erosion control

Zero-order release of oxprenolol hydrochloride was obtained by controlling the swelling and erosion of the matrix. This formulation involves only mixing of drug, hydroxypropylmethylcellulose (HPMC), and sodium carboxymethylcellulose (Na CMC) at the ratio of 1:0.4:1.6, respectively, and compressing the mixture directly into tablets. The in vitro release pattern from this optimized matrix tablet was reproducible. Accelerated stability studies revealed that the optimized formulation remains stable for an approximately 2-year shelf life. This sustained-release (SR) tablet was evaluated in dogs, and for comparison a conventional (CV) formulation was also given at the same dose level. Plasma oxprenolol levels were monitored by a sensitive and specific high-performance liquid chromatographic (HPLC) method. Significant differences in the pharmacokinetic parameters, i.e., lower Cmax, higher values of tmax, MRT, AUC, and plasma concentration at 24 hr, and nearly constant plasma levels over 12 hr, indicated that the SR matrix tablet is superior to the CV rapid-releasing formulation. The in vitro release parameters and in vivo pharmacokinetics correlated well.