Natural product and drugs interactions, its clinical implication in drug therapy management

The interaction of natural products and drugs is a common hidden problem encountered in clinical practice. The interactions between natural products and drugs are based on the same pharmacokinetic and pharmacodynamic principles as drug-drug interactions. Clinically important interactions appear to involve effects on drug metabolism via cytochrome P-450 isoenzymes, impairment of hepatic or renal function, and other possible mechanisms. To effectively counsel patients on interactions involving natural products, physicians, and pharmacists should be familiar with the most commonly used products, and have access to information on more obscure products. In this review, we describe details of drugs interaction with natural products and its impact on drug therapy management.

Effect of propofol in altering pentylenetetrazol induced seizure threshold in rats

The present study was undertaken to evaluate the role of propofol in altering pentylenetetrazol induced seizure threshold in rats. Total 42 Wistar rats were used to evaluate different parameters (onset of action, duration of seizure, seizure severity score and number of seizure) following propofol injection. The present results showed that there was significant reduction in the time required for onset of seizure in propofol treated groups following PTZ treatment. If treated with propofol alone (2 and 5 mg/kg), there was no significant difference as compared to controls. In seizure severity score assessment, there was no significant difference with various doses of propofol alone treated groups, but the difference was observed in propofol (2 and 5 mg/kg) treated groups following PTZ treatment. Duration of seizure also significantly increased in propofol (5 mg/kg) treated group, but at 2 mg/kg of propofol treatment, no significant difference was observed. The present results showed that propofol ameliorate seizure threshold and caused prolongation of duration of seizure. However, further study and trials are needed to confirm the present results.

The bird flu: a new emerging pandemic threat and its pharmacological intervention

Bird flu is an infection caused by avian influenza viruses, which are of different types A, B and C. Type A avian influenza viruses are the most frequently associated with avian influenza epidemics and pandemics. There are 16 hemagglutinin (H1 to H16) and 9 neuraminidase types (N1 to N9) identified till date. A peculiar characteristic of influenza A viruses is their propensity for genetic change by two main processes: antigenic drift (small, gradual changes) and antigenic shift (abrupt, major change producing a novel influenza A virus subtype).There are various modes of transmission of human influenza including inhalation, direct or indirect (fomite) contact etc., can have manifestations ranging from mild to severe or fatal disease, depend on the viral subtype causing the disease. Avian influenza A (H5N1) results in high death rate amongst infants and young children.The first outbreak of human infection by avian influenza viruses (H5N1) was observed in 1997 in Hong Kong. Since then a large number of outbreaks have been reported in different parts of the world. In fact, the spread of avian influenza H5N1 in various species including humans has lead to a current pandemic threat.Human avian influenza infections in persons at high risk of exposure can be prevented by adopting a series of protective measures, anti-viral vaccination and health monitoring. Drugs currently available for the treatment or prophylaxis of influenza infections include the adamantanes (amantadine and rimantadine) and the newer class of neuraminidase inhibitors (zanamivir, oseltamivir and peramivir). However, vaccines are considered the first line of defense for reducing the excess morbidity and mortality that invariably accompany pandemics and a number of clinical trials are under way to test them.

Genetic basis of HIV-1 resistance and susceptibility: an approach to understand correlation between human genes and HIV-1 infection

HIV infection is the serious medical and public health issue of present generation. By 2005, it has already infected a cumulative total of more than sixty million people worldwide and the number of HIV positive cases are rising day by day. India is currently estimated to have about 5.1 million infected persons with HIV-1 or AIDS (second only to South Africa) and this number could increase to 24 million in the next ten years. This pandemic situation of the AIDS stimulated a plethora of longitudinal cohort studies which are designed to document medical heterogeneity as well as to mitigate the factors that regulate the HIV-1 infection, disease progression and the immune defenses. In recent years these genetic studies have led to the discovery of various MHC and non MHC encoded genes, which directly or indirectly influence the susceptibility and resistance to HIV infection and AIDS. These genes and their mutated forms and their products which play a major role in determining the susceptibility or resistance to HIV-1 infection and AIDS. These genes have been categorized into MHC or non MHC encoded genes. The MHC encoded genes which determine HIV resistance or susceptibility are HLA-B57, HLA-B58, HLA-B27, HLA-Bw4 and HLA-A11 in Southeast Asians. On the other hand, non MHC encoded genes are CCR5, CCR2, RANTES, CXCL12, CXCR6, CCL3L1, Interleukin-10 (IL-10), and interferon gamma. The site specific mutations in these genes determine the susceptibility or resistance to HIV-1 infection and AIDS. In future the study of host genes in relation to HIV-1 infection may provide the researchers to develop newer chemotherapeutic approaches to prevent or cure HIV-1 infection effectively.

Longterm efficacy of topical nonsteroidal antiinflammatory drugs in knee osteoarthritis: metaanalysis of randomized placebo controlled clinical trials

OBJECTIVE

To evaluate the longterm efficacy of topical therapies for pain control in primary knee osteoarthritis (OA).

METHODS

Systematic literature search was carried out from January 1, 1966, to December 31, 2004, in Pubmed, Medline, Embase, and Cochrane database. Manual searches of related journals in the National Medical Library (New Delhi, India), the library of our institute, and conference abstracts were also carried out. We included randomized controlled clinical trials of 4 weeks or more comparing any topical nonsteroidal antiinflammatory drug (NSAID) with placebo or vehicle. Effect size for pain control was estimated.

RESULTS

Out of 172 citations, 4 studies fulfilled all the specified criteria. Four of them compared topical NSAID with placebo or vehicle. Pooled effect of topical NSAID measured at 4 weeks or beyond was superior to placebo/vehicle in pain relief (mean effect size -0.28, 95% CI -0.42 to -0.14).

CONCLUSION

Topical NSAID are effective for pain relief in knee OA for a longer duration; however, this may not hold true for all the preparations.

Antiepileptic TDM pattern at a tertiary care hospital in India

Therapeutic drug monitoring, a comparatively new investigational procedure in clinical pharmacology, is considered very beneficial to epilepsy patients though it increase the health care cost. Aim of this study was to determine the pattern of use of antiepileptic drug level monitoring over the last 7 years in our tertiary care centre and to critically comment on its utility. Retrospective data audit of archived data from 1998 to 2004 and age, sex, estimated levels of phenytoin, carbamazepine and phenobarbitone by HPLC were noted down, tabulated and compared. Chi square test was used for analysis. Three thousand five jundred thirty four blood samples of patients requesting for 4213 estimations of phenytoin, phenobarbitone or carbamazepine were received. Among the obtained samples, 44.0% (1058) were of children, 68.0% (2402) were of males, 0.6% (22) patients were getting 3 and 18.0% (635) getting 2, antiepileptic medications. 13.0% (546) samples showed level in the toxic range and 39.0% (1653) in lower range. There was increasing demand observed for estimation of antiepileptic drugs, over the 7 years. The number of abnormal values of phenytoin, phenobarbitone and carbamazepine did not show any significant difference over the years. The pattern was similar to that observed in other countries.

Effects of artemisinin, artemether, and arteether on the pharmacokinetics of phenytoin

The aim of the study was to determine the effect of artemisinin, artemether, and arteether on the pharmacokinetics of phenytoin in rabbits. In a cross-over study, phenytoin (30 mg/kg/day, o.s.) was given daily for 7 days. On day 7, blood samples were taken at various time intervals between 0 and 24 h. In the artemisinin group, phenytoin was administered for 7 days. On day 8, artemisinin alone (82 mg/kg) was administered, followed by artemisinin (41 mg/kg) along with phenytoin (30 mg/kg/day) for the next 2 days, and blood samples were drawn at various time intervals. For the artemether group, artemether (10 mg/kg, i.m.) was given on day 8, followed by artemether (5 mg/kg, i.m.) for 2 days. For the arteether group, arteether (10 mg/kg, i.m.) was given from day 8 for 3 days. Plasma phenytoin levels were assayed by HPLC, and pharmacokinetic parameters were calculated. In the artemisinin group, there was a significant decrease in t(1/2) a of phenytoin. In the artemether group, t(1/2) el decreased compared to that of controls. In the arteether group, no significant change was observed in the pharmacokinetic parameters. These results suggest that artemisinin compounds alter the pharmacokinetics of phenytoin. Confirmation of these results in human studies will warrant changes in phenytoin dose or frequency, when either of these antimalarials is coadministered with it.

Effects of Artemisinin, Artemether, Arteether on the Pharmacokinetics of Carbamazepine

The effect of artemisinin, artemether and arteether on the pharmacokinetics of carbamazepine in rabbits was studied. In a cross-over study, carbamazepine 40 mg/kg/day orally was given daily for 7 days. On day 7, blood samples were taken at various time intervals between 0 and 24 h. In the artemisinin group, carbamazepine was administered for 7 days as above. On day 8, artemisinin 82 mg/kg followed by 41 mg/kg on the 9th and 10th day along with carbamazepine 40 mg/kg/day was administered and blood samples drawn as above. Artemether 10 mg/kg i.m. was given on day 8 followed by 5 mg/kg i.m. for 2 days. Arteether 10 mg/kg i.m. was given from day 8 for 3 days. Plasma carbamazepine levels were assayed by high-performance liquid chromatography and pharmacokinetic parameters calculated. In all the groups there was an increase in the AUC(0-infinity) when carbamazepine was co-administered with artemisinin, artemether or arteether. The increase in AUC(0-infinity) (22.78 +/- 4.71 to 63.10 +/- 12.29), Cmax (2.76 +/- 0.77 to 7.02 +/- 1.08), Tmax (2.83 +/- 0.17 to 4.16 +/- 0.40) was statistically significant when artemether was given along with carbamazepine (p < 0.05). In the other groups the increase was not significant. These results suggest artemisinin compounds alter the pharmacokinetics of carbamazepine with significant change in the bioavailability. Confirmation of these results in human studies will warrant changes in carbamazepine dose or frequency when either of these antimalarials is co-administered with it.

Honey--a remedy rediscovered and its therapeutic utility

Honey is a common household product with many medicinal uses described in traditional medicine. Modern system of medicine is also finding the honey efficacious in various medical and surgical conditions. Antimicrobial, antioxidant and wound healing properties of honey are being evaluated with successful outcome. Prevention and treatment of various infections due to a wide variety of organisms and promoting surgical wound healing are some of the areas where honey is making its mark.