Enhanced stability of novel liquid compositions

1. A liquid oral pharmaceutical composition comprising:

(i) from about 0.1% to about 20% w/v polyvinylpyrrolidone;

(ii) from about 5% to about 70% w/v polyethylene glycol;

(iii) from about 1% to about 30% w/v propylene glycol;

(iv) from about 1% to 10% w/v guaifenesin; and

(v) from about 0.01% to about 1.0% w/v phenylephrine;

further comprising one or more additional pharmaceutical agent selected from the group consisting of analgesics, decongestants, expectorants, antitussives, antipyretics, anti-inflammatory agents, cough suppressants, and antihistamines; and wherein the composition comprises about less than 2% total phenylephrine degradants, as a percent weight over weight phenylephrine, and about less than 2% loss of phenylephrine from the initial total phenylephrine content, measured over a 3 month time period while stored at 40° C. and 75% relative humidity.