Long-acting phosphodiesterase 5 inhibitor, tadalafil, and superoxide dismutase mimetic, tempol, protect against acute hypoxia-induced pulmonary hypertension in rats

Long-acting phosphodiesterase 5 (PDE5) inhibitor, tadalafil, was recently approved for the treatment of pulmonary hypertension. Apart from being a PDE5 inhibitor, tadalafil also possesses antioxidant activity. The aim of this study was to probe whether tadalafil has any beneficial effect over tempol owing to its antioxidant action in addition to PDE5 inhibitory activity. Albino Wistar rats were pretreated with tadalafil (10 mg/kg) or vehicle 2 h before hypoxic exposure, whereas tempol (20 mg/kg) was given 5 min before induction of hypoxia. Right ventricular systolic pressure (RVSP), mean arterial pressure (MAP), heart rate (HR), right ventricular contractility (RVdP/dtmax) and cardiac output (CO) were recorded while subjecting rats to acute hypoxia for 30 min. Lipid peroxidation and reduced glutathione were estimated in serum before and after hypoxia exposure. Tadalafil as well as tempol significantly prevented hypoxia-induced rise in RVSP (p < 0.001) and RVdP/dtmax (p < 0.05). Both tadalafil and tempol pretreatment partially prevented (p < 0.01) the rise in CO due to hypoxia. Tadalafil did not produce any significant change in MAP, whereas tempol led to a significant fall (p < 0.01) in MAP. Acute hypoxia increased the oxidative stress levels. Tadalafil pretreatment partially prevented hypoxia-induced oxidative stress, while tempol pretreatment completely prevented hypoxia-induced oxidative stress. Results suggest that tadalafil because of its antioxidant action in addition to PDE5 inhibitory activity is more appropriate for the prevention of hypoxic pulmonary hypertension than tempol. Tempol also produced undesirable systemic hypotension as side effect, which was not seen with tadalafil because of its pulmonary selective action.

Irrational use of antibiotics and role of the pharmacist: an insight from a qualitative study in New Delhi, India

WHAT IS KNOWN AND OBJECTIVE

The overall volume of antibiotic consumption in the community is one of the foremost causes of antimicrobial resistance. In developing countries like India, pharmacists often dispense 'prescription-only' drugs, like antibiotics, to patients who do not have a prescription. Not much data is available regarding detailed information on behaviour of antibiotic use by community pharmacists which is of particular significance to develop a suitable and sustainable intervention programme to promote rational use of antibiotics. A qualitative study was conducted to understand the dispensing practices and behaviour of community pharmacists to develop policy interventions that would improve the use of antibiotics at the community level.

METHODS

Focus group discussions (FGDs) were held for five municipal wards of Delhi with retail pharmacists, public sector pharmacists and the office bearers of pharmacists' associations. Data on antibiotic use and resistance were collected earlier from these five wards. FGDs (n = 3 with 40 pharmacists) were analysed through grounded theory.

RESULTS AND DISCUSSION

Four broad themes identified were as follows: prescribing and dispensing behaviour; commercial interests; advisory role; and intervention strategies for rational use of antibiotics. FGDs with pharmacists working in the public sector revealed that, besides the factors listed above, overstock and near-expiry, and under-supply of antibiotics promoted antibiotic misuse. Suggestions for interventions from pharmacists were the following: (i) education to increase awareness of rational use and resistance to antibiotics; (ii) involving pharmacists as partners for creating awareness among communities for rational use and resistance to antibiotics; (iii) developing an easy return policy for near-expiry antibiotics in public sector facilities; and (iv) motivating and showing appreciation for community pharmacists who participate in intervention programmes.

WHAT IS NEW AND CONCLUSIONS

Inappropriate antibiotic dispensing and use owing to commercial interests and lack of knowledge about the rational use of antibiotics and antibiotic resistance were the main findings of this in-depth qualitative study. Community pharmacists were willing to participate in educational programme aimed at improving use of antibiotics. Such programmes should be initiated within a multidisciplinary framework including doctors, pharmacists, social scientists, government agencies and non-profit organizations.

Availability, price and affordability of asthma medicines in five Indian states

SETTING

States of Haryana, Karnataka, Maharashtra and Rajasthan, and Chennai (capital of Tamil Nadu State), India.

OBJECTIVE

To assess the availability, price and affordability of beclomethasone and salbutamol inhalers in five Indian states using a standardised methodology.

DESIGN

Data on the availability and price of two essential medicines for asthma, beclomethasone (50 microg/dose) and salbutamol (0.1 mg/dose) inhalers, were collated from five medicine price studies on essential medicines.

RESULTS

Beclomethasone and salbutamol inhalers were available in 25% and 30% of public facilities in Rajasthan State only. The procurement price for beclomethasone and salbutamol was respectively 0.74 and 0.56 times the international reference price (IRP). The availability of beclomethasone inhalers was poor in the private sector (10-65%) in four states. The availability of salbutamol inhalers ranged from 20% to 95% as an innovator brand and 83% to 100% as the generic. The price of beclomethasone was 0.87-1.49 times the IRP, while salbutamol cost 0.82-1.12 times the IRP. Purchasing one inhaler each of salbutamol and beclomethasone cost between 1.6 and 2.3 days' wages for the lowest paid government worker. Eighty per cent of the population earn less than this wage.

CONCLUSIONS

Essential inhalation medicines for asthma were not available in the public sector where low-income populations receive treatment. Steroid inhalers were not readily available in the private sector. Essential inhalation medicines for asthma are not affordable for the majority of the population.

Efficacy of nimesulide alone and in combination with cetirizine in acute allergic rhinitis

OBJECTIVE

To study the effect of cetirizine and nimesulide given alone and in combination in allergic rhinitis.

METHOD

A double blind, double dummy, randomised, parallel controlled clinical study in three groups consisting of 18 patients each suffering from allergic rhinitis was conducted. Group A was given nimesulide alone (100 mg BD), Group B received combination (nimesulide 100 mg + cetirizine 10 mg) and Group C was given cetirizine alone (10 mg) for one week. The efficacy of each treatment in reducing nasal stuffiness, nasal discharge, itching nose and watery eyes was assessed at base line (day 0), on days four and eight of treatment. Patients used diary cards twice daily to rate symptom severity on a four point scale.

RESULTS

Nimesulide and cetirizine alone could decrease nasal discharge, nasal stuffiness and sneezing significantly in allergic rhinitis patients by day four. Cetirizine was more effective in relieving nasal discharge and sneezing compared to nimesulide. By combining cetirizine and nimesulide four symptoms of allergic rhinitis, i.e., nasal discharge, nasal stuffiness, sneezing and watery eyes decreased significantly.

CONCLUSION

Present study has shown that nimesulide alone could decrease three symptoms of allergic rhinitis like certirizine and combination of cetirizine (anti-histaminic) and nimesulide (anti-inflammatory) exerts synergistic action in reducing symptoms in patients of allergic rhinitis.

Use of chick embryo in screening for teratogenicity

A teratology screening system would detect agents hazardous to the conceptus before they can perturb embryonic development in humans. The back log of untested chemicals and the rate at which new substances enter the market exceed the developmental effects testing by standard in vivo method. Thus, cheaper, quicker in vitro systems afford a unique opportunity for investigating the direct interaction of substances with developing morphogenetic system (MGSs), since maternal influences are excluded. As a carrier of a complete set of MGSs, the chick embryo in ovo manifests an advantage over those in vitro systems that employ isolated embryos or embryonic tissues that have only limited survival. Under controlled experimental conditions including standardization of subjects, administration technique and mode of evaluation, according to the basic principles of teratology, the chick embryo test is demonstrated to be reliable and to afford quantifiable end points for evaluation. Individual compounds, mixtures of compounds and against and antagonist can easily be administered and tested. The chick embryo possesses its own basic enzyme-catalyzed drug-transformation capacity and moreover, it can be used for screening specific human metabolites. Different newer techniques e.g. chick embryotoxicity screening test (CHEST), Chick embryo blastoderm model etc are described in detail. Chick embryo fulfills all the criteria which a test should have at a lower level of tier system in teratological studies i.e. modest laboratory equipment, moderate skill, minimal expenditure of time and money, ease of accessibility of embryo, known embryological development, possibility of experimenting on a large scale for statistically valid results and whole animals are also not required.

Aspirin by virtue of its acidic property may act as teratogen in early chick embryo

Aspirin (acetylsalicyclic acid) was dissolved either in normal saline or in phosphate buffer and was used in two doses to find out whether teratogenic potential of aspirin in chick blastoderm model is due to its acidic property or due to drug action. Drug was injected sub-blastodermally by window technique in fresh embryonated eggs after 17 hours of incubation at 39 degrees C. Eggs were re-incubated and harvested at 40 hours. Normal development of embryos was seen with normal saline and percentage of normal embryos with 30 micrograms (pH-3.19) and 120 micrograms (pH-2.64) aspirin was 31.7 and 4.9 respectively. Buffer produced 80.8% normal embryos and buffered 30 micrograms (pH-6.87) and 120 micrograms (pH-6.69) aspirin produced 67.7% and 30.8% normal embryos respectively. Changing the pH of aspirin to near neutral decreased the defect induced by aspirin but a significant effect of aspirin was observed at higher dose which could be independent of pH action.

Mechanism of aspirin induced neural tube defect in chick embryo

The effect of acetyl salicylic acid (aspirin) on neural tube development in chick embryo was studied, using the chick embryo blastoderm model. Aspirin was injected in four different doses sub-blastodermally into fresh embryonated eggs. The role of PGE1 and PGE2 alpha in the defect induced by aspirin on neural tube development in chick embryo was studied. PGE1 (5 micrograms) given after aspirin (30 micrograms) treatment was found to produce greater defect in development. All the four doses of aspirin used (i.e., 6, 30, 60 and 120 micrograms/embryo) produced significant changes (P < 0.01) in the neural tube development of chick embryo. Pre-treatment with PGE1 did not modify the defect induced by aspirin, whereas pre-treatment with PGF2 alpha prevented neural tube defects induced by aspirin. It appears that aspirin (in the doses used) affects neural tube formation by decreasing PGF2 alpha synthesis in chick embryo blastoderm.

Effect of variations in temperature of injected saline on early development of chick embryo

Development of chick embryo is sensitive to the incubation temperature and increase or decrease in incubation temperature produces defect in development but the effect of drug solution injected at variable temperatures on developing chick embryo has not been established so far. Fresh embryonated eggs were incubated and saline was administered at various temperatures after 17 hr of incubation. Embryos were harvested to see the effect of temperature variations of injected saline on neural tube formation. Normal neural tube development was seen only at 37 degrees C, hot or cold saline produced maldevelopment of neural tube. Thus it is concluded that any solution or drug which needs to be injected should ideally be used at 37 degrees C, as temperature lower or higher than that may vitiate the results.