The phrase "a certain drug" is correct and usable in written English.
It can be used when referring to a specific drug without naming it, often in discussions about its effects or implications.
Example: "The study focused on a certain drug that has shown promise in treating anxiety disorders."
Alternatives: "a specific medication" or "a particular pharmaceutical".
Part of a group of patients is treated with a certain drug; others are treated with a placebo.
A few years back, a study was published showing that a certain drug could prevent one type of cancer.
Federal law requires that drug ads include a brief summary about the possible side effects of a medication and about who should not take a certain drug.
Ms. Jaff, for instance, learned this when she was denied coverage for a certain drug her doctor prescribed for Crohn's disease.
She has a first-order desire for a certain drug and a second-order desire that her first-order desire be effective.
Arrows must be treated by rubbing with a certain drug, since their magical attributes are believed to be more effective than their technical properties.
He has a first-order desire for a certain drug, but he also has a second-order desire not to desire the drug.
Thus, the fact that a certain drug is beneficial to some sick persons does not imply that it is beneficial to all people.
If a pediatrician says, for example, that he needs a certain drug reformulated into a liquid palatable to babies, the hospital funds research to determine how this might be accomplished.
Patients with certain types of cancer now have their genes tested at diagnosis, and these tests can tell doctors whether or not a certain drug might work in that patient.
Lang and colleagues are designing trials that will still come up with the answers – for instance by comparing survival rates now at a specific treatment centre with survival rates once all patients are given a certain drug.
