public async Task <IActionResult> GetDrugs(string name, string order, int?pageNumber, int?pageSize)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            PaginatedList <Drug> drugs = await _drugRepository.ListAsync(name, order, pageNumber, pageSize);

            HttpContext.Response.Headers.Add("page", drugs.PageIndex.ToString());
            HttpContext.Response.Headers.Add("totalRecords", drugs.TotalRecords.ToString());
            return(Ok(drugs));
        }