A formulation with 7% salicylic acid and 0.05% Betamethasone dipropionate Discerner when the Carbomer gel is replaced by an HPC gel.

I can only refer to a salicylic acid gel 6% with next composition. Either set yourself Tvreden by 6% either you try or 7% achievable.

for 100 ml (= 102 g)  

R/Salicylic Acid (powder) 6 g; Antiseptic solution 16 g; HPMC 4000 2 G; NaH2PO4 2aq 100 mg; Propylene glycol 62 g and purified water 15.9 g  

1. Dissolve on NaH2PO4 2aq in a small amount of water e.g. 2 ml  

2. Blend propylene glycol and degenerated alcohol and dissolve salicylic acid and betamethasone dipropionate in this solution  

For Betamethasone Dipropionate, it may be necessary to prepare a solution in alcohol first, which will then be diluted to the appropriate concentration. Lactose is insoluble in the solvent used here  

3. Disperse HPMC 4,000 in this solution; one can use a small mixer homogenizer.  

4. Add residual amount of water

Let the HPMC dissolve and swell,   well covered, for 2 hours or longer if necessary