Procardia and still working

Long story short, last pregnancy I spent 12 weeks on bedrest and procardia for pre term contactions. This pregnancy, dr went ahead and gave me a script for procardia "to be taken as needed every 8 hours" because I felt like contactions are definitely picking up. I took one last night and got the typical racing heart, weak, near fainting feeling, sweating and red swelling legs. Anyone take procardia while at work if contractions start up with these bad side effects? I don't see how I can deal with these side effects at work. At home, doable. I will do whatever it takes to keep this baby in (don't get me wrong)- but I don't know if I can do this physically 5 days a week.