Liquorice derivatives

Liquorice derivatives (carbenoxolone) and degly-cyrrhizinised liquorice, formerly used for peptic ulcer, are now obsolete. 

Liquorice derivatives have a long history of use, and an extracted principle carbenoxolone is of proven value, and, though its mechanism of action is not clear, it is thought to work by effecting cytoprotection protective secretions. Some complexes, e.g. sncralfiite (aluminium hydroxide and sulphated sucrose) may be of value. 

The single dose of a drug is mo.stly derived from experience it is only possible in a very few cases to calculate it from the activity of the constituents. However, as many herbal drugs arc only weakly active and contain non-toxic substances, i.e, the therapeutic index is large, exceeding the dose is usually only of minor significance nevertheless, the pharmacist must know what the exceptions are in this book, the sections on Side effects and Making the tea draw particular attention to such cases, c.g. arnica flowers, liquorice root, etc. 

Carbenoxolone is a derivative of glycyrrhizic acid and both carbenoxolone and liquorice have ulcer healing properties. However, carbenoxolone has considerable mineralocorticoid activity, frequently producing Na+ and fluid retention, hypertension and hypokalemia. It is therefore not generally recommended for routine use. 

It is a steroid like triterpenoid synthetic derivative of glycyrrhizic acid (obtained from liquorice) and has been found to be effective in healing both gastric and duodenal ulcer without affecting volume or acidity of gastric juice. 

Figure 50. Identification of liquorice root dry extract (DE) using two TLC systems after deriv-atization with vanillin-snlfnric acid reagent...

A valid criticism of the technique (similar to that mentioned by Lorenz for rat-paw oedema) has recently been made by Gygielman and Robson , who observed that anti-inflammatory activity, determined by the cotton pellet test, of a group of substances derived from liquorice seems to be associated with irritant effects at the site of injection. They proceeded to show that the injection of known irritants such as antimony potassium tartrate and croton oil produces a significant reduction in granulation tissue. Robinson and Robson suggested, in the light of further experiments, that the reason for this is that an anti-inflammatory factor is produced at the site of implantation of the irritant substance. 

Dossie lists tobacco juice among various organic browns such as Spanish juice (derived from liquorice see Spanish brown) and asphaltum (see asphalt), although he does not describe it (Dossie, 1764). 

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