Propoxyphene, molecular model. This is an opiod analgesic (painkiller) drug that has been withdrawn from use in many countries. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), oxygen (red) and nitrogen (blue).

Ritalin. Molecular model of the stimulant drug methylphenidate, marketed as Ritalin. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), oxygen (red), nitrogen (blue).

THC drug molecule. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white) oxygen (red).

Levofloxacin antibiotic, molecular model. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (dark blue), oxygen (red) and fluorine (light blue).

Caffeine molecule, illustration

Isosorbide mononitrate, molecular model. This drug is used to treat angina. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), oxygen (red) and nitrogen (blue).

Loratadine, molecular model. This antihistamine drug is marketed as Claritin. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue), oxygen (red) and chlorine (green).

Cocaine drug, molecular model. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (silver), oxygen (red) and nitrogen (blue).

"Prednisolone corticosteroid drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red). "

Methadone molecule, computer model. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), nitrogen (blue) and oxygen (red).

Azithromycin, molecular model. This antibiotic drug is marketed as Zithromax and Sumamed. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), oxygen (red) and nitrogen (blue).

Malathion, molecular model. This is an organophosphate pesticide. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white), oxygen (red), sulphur (yellow) and phosphorous (orange).

"Neostigmine drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Tropicamide mydriatic eye drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Kanamycin antibiotic drug molecule (aminoglycoside). Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Tetracaine local anesthetic drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Indacaterol COPD drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Tetracaine local anesthetic drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Indacaterol COPD drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Paromomycin aminoglycoside antibiotic drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Kanamycin antibiotic drug molecule (aminoglycoside). Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Tropicamide mydriatic eye drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

"Prednisolone corticosteroid drug molecule. Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (black), oxygen (red). "

"Peramivir influenza drug molecule (neuraminidase inhibitor). Atoms are represented as spheres with conventional colour coding: hydrogen (white), carbon (grey), oxygen (red), nitrogen (blue). "

Naproxen, molecular model. This is an anti-inflammatory and analgesic (painkiller) drug. Atoms are represented as spheres and are colour-coded: carbon (grey), hydrogen (white) and oxygen (red).