Both players appeared before an RFU Disciplinary Panel on Tuesday for their role in a mass-brawl that broke out during their Zurich Premiership clash with Gloucester on November 1.
Drahm and Robinson were cited alongside Gloucester fly-half Duncan McRae and flanker Andy Hazell for the incident, but while McRae, who was cited for striking Drahm, had his case dismissed – Drahm received a two-week suspension for the same offence.
Northampton appealed the ruling and the case was heard on Thursday by arbitrator Jononthan Dance, who, in turn, overturned the rulings.
The reduced sentences mean that Drahm will now be available for Saints' Powergen Cup match against Bath on Saturday, while Robinson will be available for the return clash against Gloucester at Kingsholm.
