New Drugs: Adverse drug interactions

Medication management at home: medication-related risk factors associated with poor health outcomes

BACKGROUND

Some patients may have medication-related risk factors only identified by home visits, but the extent to which those risk factors are associated with poor health outcomes remains unclear.

OBJECTIVE

To determine the association between medication-related risk factors and poor patient health outcomes from observations in the patients' homes.

DESIGN

Cross-sectional study.

SETTING

Patients' homes.

SUBJECTS

204 general practice patients living in their own homes and at risk of medication-related poor health outcomes.

METHODS

Medications and medication-related risk factors were identified in the patients' homes by community pharmacists and general practitioners (GPs). The medication-related risk factors were examined as determinants of patients' self-reported health related quality of life (SF-36) and their medication use, as well as physicians' impression of patient adverse drug events and health status.

RESULTS

Key medication-related risk factors associated with poor health outcomes included: Lack of any medication administration routine, therapeutic duplication, hoarding, confusion between generic and trade names, multiple prescribers, discontinued medication repeats retained and multiple storage locations. Older age and female gender were associated with some poorer health outcomes. In addition, expired medication and poor adherence were also associated with poor health outcomes, however, not independently.

CONCLUSION

The findings support the theory that polypharmacy and medication-related risk factors as a result of polypharmacy are correlated to poor health outcomes.

Oil-in-water lipid emulsions: implications for parenteral and ocular delivering systems

Lipid emulsions (LEs) are heterogenous dispersions of two immiscible liquids (oil-in-water or water-in-oil) and they are subjected to various instability processes like aggregation, flocculation, coalescence and hence eventual phase separation according to the second law of thermodynamics. However, the physical stability of the LE can substantially be improved with help of suitable emulsifiers that are capable of forming a mono- or multi-layer coating film around the dispersed liquid droplets in such a way to reduce interfacial tension or to increase droplet-droplet repulsion. Depending on the concentrations of these three components (oil-water-emulsifier) and the efficiency of the emulsification equipments used to reduce droplet size, the final LE may be in the form of oil-in-water (o/w), water-in-oil (w/o), micron, submicron and double or multiple emulsions (o/w/o and w/o/w). The o/w type LEs (LE) are colloidal drug carriers, which have various therapeutic applications. As an intravenous delivery system it incorporates lipophilic water non-soluble drugs, stabilize drugs that tend to undergo hydrolysis and reduce side effects of various potent drugs. When the LE is used as an ocular delivery systems they increase local bioavailability, sustain the pharmacological effect of drugs and decrease systemic side effects of the drugs. Thus, the rationale of using LE as an integral part of effective treatment is clear. Following administration of LE through these routes, the biofate of LE associated bioactive molecules are somehow related to the vehicles disposition kinetics inside blood or eyeball. However, the LE is not devoid from undergoing various bio-process while exerting their efficacious actions. The purpose of this review is therefore to give an implication of LE for parenteral and ocular delivering systems.

Clinical pharmacology and therapeutic drug monitoring in neonates and children

From a pharmacotherapy perspective, the process of development and growth represents an unstable and dynamic condition. Age-related changes in drug absorption, distribution, and metabolism among neonates, infants, and prepubescent children create a unique situation that may increase drug toxicity of some agents and protect from toxicity of other agents. Understanding the age-related changes in drug disposition that are relevant for therapeutic response and toxicity is essential for optimizing pharmacotherapy at different stages of childhood.

Inadequate recording of alcohol-drinking, tobacco-smoking and discharge diagnosis in medical in-patients: failure to recognize risks including drug interactions

The records of 62 men and 43 women, 14-88 years old, admitted to general medical wards in a public teaching hospital during 1991 were examined for discharge medications and for the recording of alcohol-drinking, tobacco-smoking and discharge diagnosis. Drinking and smoking status was unrecorded in 22.9% and 21.9% of patients respectively. Twenty-four patients had 31 potential drug interactions which were related to the number of drugs prescribed and to drinking alcohol; 10.5% of the patients had interactions involving alcohol and 2.9% tobacco. Six patients received relatively or absolutely contraindicated drugs, including one asthmatic given two beta-blockers. The drugs prescribed indicated that some patients had conditions such as gastro-oesophageal disorders, diabetes and obstructive airways disease which had not been recorded. Inadequate recording of diagnoses, alcohol and smoking status creates risks to patients and may cause opportunities for preventive care to be missed. This study provides the basis for the development of undergraduate and postgraduate education programmes to address these issues and so decrease risks to patients which arise from inadequate recording practices. Incomplete diagnoses also adversely affect hospital funding where this depends on case-mix diagnostic groups. Quality assurance programmes and other strategies are being implemented to improve medical recording and prescribing habits.

A primer of drug safety surveillance: an industry perspective. Part II: Product labeling and product knowledge

OBJECTIVE

To place the fundamentals of clinical drug safety surveillance in a conceptual framework that will facilitate understanding and application of adverse drug event data to protect the health of the public and support a market for pharmaceutical manufacturers' products. Part II of this series discusses specific issues regarding product labeling, such as developing the labeling, changing the labeling, and the legal as well as commercial ramifications of the contents of the labeling. An adverse event report scenario is further analyzed and suggestions are offered for maintaining the product labeling as an accurate reflection of the drug safety surveillance data. This article also emphasizes the necessity of product knowledge in adverse event database management. Both scientific and proprietary knowledge are required. Acquiring product knowledge is a part of the day-to-day activities of drug safety surveillance. A knowledge of the history of the product may forestall adverse publicity, as shown in the illustration.

DATA SOURCES

This review uses primary sources from the federal laws (regulations), commentaries, and summaries. Very complex topics are briefly summarized in the text. Secondary sources, ranging from newspaper articles to judicial summaries, illustrate the interpretation of adverse drug events and opportunities for drug safety surveillance intervention.

STUDY SELECTION

The reference materials used were articles theoretically or practically applicable in the day-to-day practice of drug safety surveillance.

DATA SYNTHESIS

The role of clinical drug safety surveillance in product monitoring and drug development is described. The process of drug safety surveillance is defined by the Food and Drug Administration regulations, product labeling, product knowledge, and database management. Database management is subdivided into the functions of receipt, retention, retrieval, and review of adverse event reports. Emphasis is placed on the dynamic interaction of the components of the process. Suggestions are offered to facilitate communication of a review of adverse event data for various audiences.

CONCLUSIONS

Careful drug safety surveillance is beneficial to the health of the public and the commercial well-being of the manufacturer. Attention to the basic principles is essential and, as illustrated, may be sufficient to resolve some problems.

Drug interactions in epilepsy

The abolition of seizures using a single antiepileptic agent can be expected in more than 80% of patients, although not necessarily with the first drug tried. The remainder often receive polypharmacy, and current evidence suggests that perhaps only around 10% of these benefit significantly in terms of improved seizure control. Many more experience complicated drug interactions. Carbamazepine, phenytoin, phenobarbital, and primidone (metabolized in part to phenobarbital) all induce the synthesis of hepatic monooxygenase and conjugating enzymes. This will result in an acceleration in the metabolism of other lipid-soluble drugs with likely attenuation of their pharmacological effects. Valproate, on the other hand, is a minor enzyme inhibitor. Pharmacokinetic interactions are almost invariable when more than one antiepileptic drug is coprescribed. The extent and direction of interactions with combinations of these drugs are varied and unpredictable. Discontinuation of an enzyme inducer or inhibitor will influence the concentrations of the remaining drug(s). Pharmacodynamic interactions also cause problems in epileptic patients. A number of commonly prescribed psychoactive drugs, such as tricyclic antidepressants and neuroleptics, can worsen seizure control by reducing the convulsion threshold. In addition, there seems little doubt that ethanol abuse and withdrawal can precipitate seizures in susceptible patients. Antiepileptic polypharmacy is more likely to impair cognitive function than the same drugs used singly. In addition, the more antiepileptic drugs received by a patient in the first trimester of pregnancy, the higher the risk of teratogenesis in the exposed infant. Drug interactions prolong and complicate the process of new drug assessment, particularly when introduced in treated patients with refractory epilepsy. The candidate antiepileptic drug may alter the concentration of concomitant therapy, or its own breakdown may be influenced by coprescribed enzyme inducers or inhibitors. Even if the new drug is excreted unchanged by the kidney, unexpected interactions can be uncovered. Pharmacodynamic interactions need not always be detrimental. Currently, there is no rational approach to the treatment of intractable epilepsy. As more new drugs with single mechanisms of action become available, the potential exists for combining these synergistically. This approach may revolutionize the pharmacological management of the epileptic patient in the 21st century.

Halothane in children with chronic liver disease

Exacerbation of pre-existing liver disease after halothane anaesthesia has been reported in adult patients. A prospective study was performed in 38 children with biopsy-proven liver disease to assess the effect of surgery and halothane anaesthesia on liver function. Plasma liver enzyme levels were measured immediately preoperatively and again four to eight days after surgery and halothane anaesthesia. Minor elevations of both AST and ALT occurred in four patients but this was not associated with a clinical deterioration in the patients' postoperative recovery. In the children studied pre-existing liver disease did not predispose to a deterioration of liver function following surgery and halothane anaesthesia.