Drugs are vital to saving and improving public health. However, medicines are often not available at the facility because stocks run out or in particular, pharmaceuticals are not available due to a shortage of supplies. Implementation of pharmacy services should ensure safe, quality, usable and affordable availability drug. A systematic review was conducted to identify related studies. Electronic databases used to identify relevant studies are, ScienceDirect, Plos, PubMed and Google Scholar. This study is limited to English and publications from 2007 to 2017. The electronic database search earned 33 articles while only six studies met the criteria for review. There is the relatively low availability of drugs in some developing countries and the average availability of generic drugs is better than Innovator Brand drugs, especially in the public sector. Most of the factors that may affect drug availability are related to government policies to improve drug access and lower prices so that national drug policy review in each country is required. Overall, the method used to measure the availability of drugs using a reference method used by WHO Health Action International. The availability of drugs in low, lower and upper middle countries still need to be improved by
increasing drug access and enhancing prices by using appropriate government policies. The WHO HAI method is effectively used to measure the availability of drugs by using the core drug and supplementary drug references by the established reference.
Key words: Drug Availability, Overview, Influencing Factors, Several Low, Lower and Upper-Middle Countries.