composition (% w/w), and preferably in an amount of 1 to 20% w/w based on the total weight of the composition.The carrier medium is present in an amount of up to 99.99% by weight, for example 10 to 95 wt-%, based on the total weight of the composition.In one embodiment the carrier medium comprises a water-soluble polymer, preferably a cellulose derivative such as hydroxypropylmethylcellulose (HPMC