The Argument:
The following letter was printed in a medical journal:
Many non prescription drugs can cause serious side effects, particularly when taken in conjunction with other drugs or in large quantities. If these potentially harmful non prescription drugs were sold only by prescription, then a doctor or pharmacists would be able to explain the possible side effects of he drugs and would also be able to monitor the quantity of the drug purchased, thereby decreasing the chance that a person would take too much of the drug. Therefore, any drug with potentially serious side effects should be sold only by prescription.
AWA/My Answer:
The argument mentioned above has a central theme of possible side effects of non prescribed drugs when taken in conjunction with other drugs or when taken in large quantities. The underlying assumption that is being made here is that the person who is taking the drugs is not rational enough to think about what quantities to take the drugs in or consult a doctor before consuming any. And since most of the non prescribed drugs available are mostly for common diseases believing that it can have such a side effect is a bit too extreme.
The author of the passage may or may not hold credibility as nothing is mentioned about the author but since the article is mentioned in the medical journal may be the author does hold some knowledge (to say the least) in the field of medicine. The author goes on suggesting that if these drugs are sold with prescription then the quantity of it being sold can be controlled and eventually decreases the chance of person taking too much drugs. This does sound convincing because the author does not mention anything about which types of drugs are being considered and how in real world this can be implemented. It might be very logical for quantities to be sold in limited number but the ground reality of how it will be implemented remains in question.
The author provides no explanation of the geography being considered. If we consider a country like United States, the non prescribed drugs are very limited in nature and are mostly available for reasons like cold and cough and may be something bit more than that. In such a regulated country it becomes very difficult for a person to buy something which can have severe side effects. But if a country like India is considered then a lot of reasoning changes and the whole implementation also becomes a question.
The author also makes a contrary statement in the end by saying a drug with potential side effects should be sold with prescription which is true but it assumes that such drugs are sold without prescription which is not correct. As author points out in the beginning the side effect can occur from conjunction with other drugs or large quantities which is human error rather than the drug itself being the reason for it.
The whole argument highlights one thing in the positive direction, any of the non prescription drugs available should be well tested for any potential side effects, must be certified by Federal authorities and must be only then be available for sale as non prescribed. This does not mean that once listed as a non prescribed drug it should always be like that. Such drugs should be evaluated from time to time and changes should be made based on available data. And while doing so it should be identified which are the drugs are the most likely for causing such side effects and must be tracked. And since a person who in his or her right mind buys such drugs should be well aware of doses to consume such drugs or consult a doctor before consuming.
Source: McGraw Hill GMAT 11th Edition. Diagnostic Test.
Note: I used a MS Word and I managed to save 3 minutes at the end. Thank you