There is a new article on Free Drug Samples in the Public Library of Science.
Summary: Drug samples are bad. Doctors are people, and are subject to manipulation by marketers the same as anyone else. The multi-billion dollar pharmaceutical companies give out samples in ways that make them more money, increasing awareness of expensive new drugs, irrespective of the effects on national health. These companies lobby the government to make sure they can keep doing this, even though it is bad. Samples are not used to help the poor, and are often used by the doctors or given to friends since they are not monitored. Lack of monitoring and involvement of pharmacists also leads to negative drug interactions and a lack of consumer education. Socialized health care systems are relatively impervious to manipulation by samples.
If you follow the link, also read the comment by Ken Johnson, Senior Vice President of Communications for the Pharmaceutical Research and Manufacturers of America. Obviously biased, he presents some data that does not really contribute to his argument. He supports the idea that drug samples give people treatment for their problems, ignoring that the main article already discussed this, and how poorer patients often discontinue these drugs cold-turkey when the freebies run out. Ken argues that most prescriptions are still for generics, which is a distraction from the problem that still more expensive new drugs are being prescribed than should be. His argument is like saying that it's okay to set some houses on fire because most houses will still not be on fire. Was the KRC survey of prescribers? Of course they don't think they're influenced by marketers over journal articles and clinical formularies. Ken goes on to point out that drug expenditures have gone down, and payers influence prescription decisions, both of which may be true, and neither of which counters the points of the main article. Then he says that 75% of physicians report using samples to reduce costs for patients, which combined with the main article means that they're reducing costs mostly for non-poor patients. Remember that the samples also work as a hook to get people using who can actually pay for more. Finally he repeats that free drugs are good, again ignoring long-term ramifications of only temporary and undermonitored, underexplained free drugs.