compounds of general formula i may be in a form suitable for oral use for example as tablets troches lozenges aqueous or oily suspensions dispersible powders or granules emulsion hard or soft capsules or syrups or elixirs compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents flavoring agents coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations tablets contain the active ingredient in admixture with non toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets these excipients may be for example inert diluents such as calcium carbonate sodium carbonate lactose calcium phosphate or sodium phosphate granulating and disintegrating agents for example corn starch or alginic acid binding agents for example starch gelatin or acacia and lubricating agents for example magnesium stearate stearic acid or talc the tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period for example a time delay material such as glyceryl monostearate or glyceryl distearate may be employed formulations for oral use may also be presented as.