Background: The successful diffusion of new drugs is crucial for both pharmaceutical companies and patients-and of wider stakeholder concern, including for the funding of healthcare provision. Micro-level characteristics (the socio-demographic and professional characteristics of medical professionals), meso-level characteristics (the prescribing characteristics of doctors, the marketing efforts of pharmaceutical companies, interpersonal communication among doctors, drug attributes, and the characteristics of patients), and macro-level characteristics (government policies) all influence the diffusion of new drugs. This systematic literature review examines the micro-and meso-level characteristics of early prescribers of newly introduced drugs. Understanding the characteristics of early adopters may help to speed up the diffusion process, promote cost-efficient prescribing habits, forecast utilisation, and develop targeted intervention strategies. Methods: The PubMed and Scopus electronic databases were chosen for their extensive coverage of the pertinent literature and used to identify 205 potentially relevant studies by means of a four-layered search string. The 35 studies deemed eligible were then synthetized carefully and critically, to extract variables relevant to this review. Results: Early adoption of new drugs is not a personal trait, independent of drug type, but early adopters share both micro-and meso-level characteristics. At prescriber level, doctors' interest in particular therapeutic areas, participation in clinical trials, and volume of prescribing-either in total or within the therapeutic class of the new drug-increase the likelihood of early adoption. The marketing efforts of pharmaceutical companies and doctors' professional and social interactions leading to prescribing contagion are very powerful predictors of new drug uptake. At patient level, doctors with younger patients, patients with higher socioeconomic statuses and/or patients with poorer health statuses are more inclined to prescribe new drugs early. In contrast, the socio-demographic characteristics of prescribers and many practice-related factors play little role in the adoption process. Conclusions: The most powerful predictors of new drug uptake include the doctors' strong scientific commitment, high prescribing volume in total or in within the therapeutic class of the new drug, high exposure to marketing, and intense communication with colleagues.
