you may survey general public asking them about whichOTC drugs they frequently consume for respective conditions. For prescription drugs, you may review the prescriptions (from clinics or pharmacy) to look for the commonly prescribed drugs. But again, there are number of drugs for multiple conditions, you may want to break your study based on different medical conditions. Else, you may do a systematic review of the existing literature. Good luck.
In epidemiological perspective, A cross sectional survey is a quick way for you to draw a conclusion regarding popular medications use. However, the answer you obtained would be limited to the way you set the questionnaire and how much you know about popular medication. On the other hand, if you are interested to explore from the respondent perspective, e.g. the respondents' meaning and interpretation, the experience and feeling, the motives and intentions, that direct their behaviour in using a particular type of medication in their everyday lives, I would suggest you use qualitative interview method. Also, A mixed method study started with qualitative interview first to explore as many as possible meaningful data from the respondents that aims to provide extra input in constructing a survey questionnaire for the larger population.
Never ask a question to which you don't already know the answer. Out-of-the-square strategies are of use here, as a 'finger in the air'. To consider patient usage for the condition of interest, I'm keen on subscriber data from a Patient Reported Outcome site. https://www.patientslikeme.com/patients allows a filter by Country and meds.
In the US, there is a commercial service called IMS American that tracks pharmaceutical sales and reports prescriptions written. There may be a comparable service in the UK. Professional pharmacists societies may know who these organizations are in your country. In addition, the NHS most likely collects this information in order to develop budget data.
I would make a friendly suggestion - to keep in mind how we ask graduate students about their research: We expect a clear statement of purpose within a specific scope of study "Info. about popular medications" is far too vague. Do you mean Subjective opinions/beliefs about effectiveness of popular meds? Objective clinical studies about effectiveness of popular meds? 'Popular' medications from the perspective of physicians or 'popular' from the perspective of the consumer? Market share trends among popular meds? Attitudes as to compliance or deliberate overuse of popular meds? Records of toxic events/accidental poisonings from popular meds? Trends among manufacturers to increase/decrease manufacture of popular OTC remedies in favour of prescription meds? Interactions/contraindications discovered? ...etc. .... The list goes on, with different resources in each case.
thank you for your clarification. I asked this question regarding the scientific tools for collection of data about the popular medication that are being prescribed by doctors to specific diseases in region there is no records or documentations about medications moreover there is no guideline for the prescription in other words the prescription is randomly and according to the doctors point of view which it totally not acceptable so i can not depend on unreliable data that is way I asked for an alternative data collection tools .Is it acceptable to collect information by submit list of medication to doctors and they tick the choice !
I think now you realize that i ask question but the data will be unreliable and statistically may be weak
First you need to explain what do you mean by popular medications? Popular in marketing or population in use. There are a number of approaches to get some sort of answer.
1. Pattern of prescriptions in the ambulatory care institutions ( frequency of drugs dispensed over a year), hospitals ( frequency of drugs dispensed over a year)and private clinics ( adequate sample of drug prescriptions from pharmacies).
2. A sample population survey. asking people about the drugs they consumed over a month period.
3. National/ regional /local drug suppliers statistics over 1-2 years