I've been taking azithromycine each second day, one pill. Tomorrow I will take 250 mg pill at 2 pm and have a party at 7 pm - can I drink alcohol?

To good health. If you are taking antibiotics for an infection -in your case azithromycin, you should really focus on getting well. Especially since you are still early in the treatment. This means, staying up late, drinking alcohol etc are not recommended. Is this going to harm you? Probably not if it is only one drink but you should give your body a break since alcohol is a toxin, technically speaking.