Understanding the essentials of drug interactions: a potential need for safe and effective use of drugs.

Drug interactions (DIs) represent an important and widely under recognized source of medication errors. An interaction is said to occur when the effects of one drug are changed by the presence of another drug(s), food, drink or an environmental chemical. When a therapeutic combination could lead to an unexpected change in the condition of the patient, this would be described as an interaction of potential clinical significance. DIs can arise in numerous ways; such as pharmacodynamic interaction, in which receptor effects of different agents interacts to produce synergy or antagonism of drug effects. In pharmacokinetic interaction, the blood levels of given agents may be raised or lowered based on the type of interaction. Special attention and thorough monitoring is needed for the patients who are predisposed to develop DIs and those on drugs with narrow therapeutic index. DIs can be a very important contributory factor for the occurrence of adverse drug reactions and adverse drug events. DIs monitoring programs should be initiated and strengthened in order to minimize their occurrence. Herbal drug interactions and DIs comprising over the counter medicines should also be considered seriously.

Interaction between warfarin and tamoxifen: a case report.

Warfarin is a commonly used anticoagulant with documented reports of drug interactions. Tamoxifen is used in the adjuvant hormonal treatment of women with oestrogen-receptor- positive breast cancer. Warfarin and tamoxifen are known to interact with each other with a resultant increase in the bleeding tendency. These reports are mainly from the white population. We report a case of drug interaction between warfarin and tamoxifen with an acute onset. This report suggests that when these drugs are co administered, careful monitoring of the coagulation profile is needed.

Contribution of the regional drug information center towards drug safety.

Drug related complications may lead to huge economic impact and cause significant morbidity and mortality. The present study analyzed the services provided by our Drug Information Center (DIC) in relation to drug safety. Over a period of one year, the DIC received 336 drug related queries. Among these 127 queries were related to drug safety. Medical doctors asked 78% of queries and patient care was the purpose behind 64.6% of them. Half (50%) of the enquirers submitted their queries to the center personally or contacted the DIC staff. Forty one percentage of the queries were related to the causality of particular drug towards adverse drug reactions and 10 % regarding drug use in pregnancy and lactation. Centrally acting drugs accounted for 21% of the queries. Twenty two percentage of the enquirers required an immediate answer. DICs by providing unbiased and objective information can reduce the occurrences of drug related complications.

A study on rational drug prescribing and dispensing in outpatients in a tertiary care teaching hospital of Western Nepal.

OBJECTIVES: To analyze the prescriptions of out-patients for rational prescribing and dispensing and to evaluate the patient's knowledge regarding use of drugs, using INRUD indicators. METHODS: A cross-sectional, descriptive study was conducted at the Manipal Teaching Hospital, Pokhara, Nepal during the time period from June 10th to August 19th 2004. RESULTS: Totally 247 prescriptions were randomly selected for analysis, wherein 720 drugs were prescribed. Only 15% of drugs were prescribed by generic name, 21.67% of the total drugs consisted of fixed-dose combinations, only 40% of drugs were from the Essential drug list of Nepal and 29.44% (n=212) were from the WHO Essential drug list. It was found that more than half (54.17%) of the drugs were from Nepalese National Formulary and 35.69% were from WHO model formulary. Dermatological products were most commonly prescribed followed by drugs acting on central nervous system, antimicrobials and drugs acting on cardiovascular system. Among the drugs dispensed, 79.16% were oral followed by topical (18.19%) and parenteral forms (2.98%). Diagnosis was mentioned only in 3.23% (n=8) of the prescriptions and the average cost per prescription was found to be 241.11 Nepalese rupees (US$ 3.26). It was found out that pharmacist labelled only 0.4% of the medication envelopes with the name of the patient. However, 82.6% of the medication envelopes were labelled with name of the drug and 87.0% with drug strength. Only 53.8% (n=133) of the patient knew both the duration of the therapy and administration time of drugs. CONCLUSION: There is a need for educational intervention for prescribers and both managerial and educational intervention for the hospital pharmacists to improve prescribing and dispensing.

Safety monitoring of drugs--where do we stand?

Drug related complications, a major cause of hospitalizations, lead to huge economic burden and significant human suffering. New chemical entities enter the market without sufficient safety data on patient population making rare (Adverse Drug Reactions) ADRs undetected in the clinical trials. ADR monitoring helps in detecting the occurrence of rare and unknown ADRs and helps in prevention of further occurrence. Several methods are adopted for effective monitoring of ADRs. An effective ADR monitoring program requires adequate infrastructure and trained manpower. In developed countries, the ADR monitoring system is well established. In Nepal, the concept of ADR monitoring is in the infant stage. A simple approach for ADR monitoring may be helpful in starting an ADR monitoring program in hospital setups in Nepal. Though it is difficult to prevent ADRs, a systematic approach will definitely helps in minimizing the further occurrence of similar ADRs.

Therapeutic dimensions of ACE inhibitors--a review of literature and clinical trials.

In the 1970s, pharmacological therapy interrupting the renin-angiotensin system was considered beneficial for patients with high-renin hypertension. This gave rise to the development of ACE inhibitors. Surprisingly, the ACE inhibitors proved to be effective not only in patients with high renin hypertension, but also in many patients with normal levels of plasma renin activity. At present ACE inhibitors have a significant position in a wide range of chronic illnesses such as atherosclerosis, hypertension, myocardial infarction, diabetic complications, stroke etc. They are combined safely with drugs like angiotensin receptor blockers, calcium channel blockers and thiazides with varying degree of benefits. Though they are safe drugs, patients need monitoring for renal insufficiency, hypotension, hyperkalemia etc. The safety of these drugs in paediatrics patients is not established. It is better to avoid these drugs during pregnancy.