A ALIMENTARY TRACT AND METABOLISM

 B BLOOD AND BLOOD FORMING ORGANS

 C CARDIOVASCULAR SYSTEM

 D DERMATOLOGICALS

 G GENITO URINARY SYSTEM AND SEX HORMONES

 H SYSTEMIC HORMONAL PREPARATIONS, EXCL. SEX HORMONES AND INSULINS

 J ANTIINFECTIVES FOR SYSTEMIC USE

 L ANTINEOPLASTIC AND IMMUNOMODULATING AGENTS

 M MUSCULO-SKELETAL SYSTEM

 N NERVOUS SYSTEM

   N01 ANESTHETICS

   N02 ANALGESICS

     N02A OPIOIDS

       N02AA Natural opium alkaloids

       N02AB Phenylpiperidine derivatives

       N02AC Diphenylpropylamine derivatives

       N02AD Benzomorphan derivatives

       N02AE Oripavine derivatives

       N02AF Morphinan derivatives

         N02AF01 Butorphanol [DG:DG00821]

         N02AF02 Nalbuphine [DG:DG00822]

       N02AG Opioids in combination with antispasmodics

       N02AJ Opioids in combination with non-opioid analgesics

       N02AX Other opioids

     N02B OTHER ANALGESICS AND ANTIPYRETICS

     N02C ANTIMIGRAINE PREPARATIONS

   N03 ANTIEPILEPTICS

   N04 ANTI-PARKINSON DRUGS

   N05 PSYCHOLEPTICS

   N06 PSYCHOANALEPTICS

   N07 OTHER NERVOUS SYSTEM DRUGS

 P ANTIPARASITIC PRODUCTS, INSECTICIDES AND REPELLENTS

 R RESPIRATORY SYSTEM

 S SENSORY ORGANS

 V VARIOUS