```ruby
require_dependency 'renalware/drugs'

module Renalware
  module Drugs
    class Drug < ActiveRecord::Base

      acts_as_paranoid

      has_many :medications, as: :medicatable, dependent: :destroy
      has_many :patients, through: :medications, as: :medicatable
      has_and_belongs_to_many :drug_types, class_name: "Type",
        association_foreign_key: :drug_type_id

      validates :name, presence: true

      scope :antibiotic, -> { joins(:drug_types).where(:drug_types => {:name => "Antibiotic"}) }
      scope :esa, -> { joins(:drug_types).where(:drug_types => {:name => "ESA"}) }
      scope :immunosuppressant, -> { joins(:drug_types).where(:drug_types => {:name => "Immunosuppressant"}) }
      scope :peritonitis, -> { joins(:drug_types).where(:drug_types => {:name => "Peritonitis"}) }

      def display_type
        "Standard Drug"
      end

      def to_s
        name
      end
    end
  end
end
```

Remove unused association causing circluar dependencies
user
```ruby
require_dependency 'renalware/drugs'

module Renalware
  module Drugs
    class Drug < ActiveRecord::Base

      acts_as_paranoid

      has_and_belongs_to_many :drug_types, class_name: "Type",
        association_foreign_key: :drug_type_id

      validates :name, presence: true

      scope :antibiotic, -> { joins(:drug_types).where(:drug_types => {:name => "Antibiotic"}) }
      scope :esa, -> { joins(:drug_types).where(:drug_types => {:name => "ESA"}) }
      scope :immunosuppressant, -> { joins(:drug_types).where(:drug_types => {:name => "Immunosuppressant"}) }
      scope :peritonitis, -> { joins(:drug_types).where(:drug_types => {:name => "Peritonitis"}) }

      def display_type
        "Standard Drug"
      end

      def to_s
        name
      end
    end
  end
end
```
assistant