Unfortunately, for your friend the options are very limited.  Over the last twenty years there have really been no knew developments in the anti-anxiety medicaiton field with the exception of the newer SSRI's that also work on norepinephrine. These medications became very commonly used because they helped patients with both depression and anxiety thought to almost allways co-exist.   I believe for patients experiencing average anxiety attacks over short periods of time that are more situational than organic in nature they do offer some help at higher doses.  Beware, however the higher the dose, the more profound and common the side effect profile becomes. So talk straight up to the doctor, pharmacist and always have someone know you have started taking them to monitor you as you adjust to the new med and each dosage titration.   On the other hand for patients who have serious and life limiting anxiety or panick attacks there just are not many options other than benzodiazipines including xanax, clonipin, ativan and so on.  These drugs differ in how quickly they take effect, how long they stay in the system, sleepiness (some are used strictly as sleeping drugs), and thier side effects.   The big drawback with any benzo for the true anxiety patient who will likely be on them for longer periods of time are their addictive qualities, tolerance (where your body needs a higher dosage to accomplish the same outcome and, the danger of patients trying to go off of them cold.  Patients should be highly cautioned that going "cold turkey" off any benz can result in siezure.  Also, a strong mention against combining these agents with even small levels of alchol.   There have been a few drugs over the last years that claimed comparable effectiveness without the addictive quality but I have yet to hear personal feedback suggesing this is so and have not seen them pop in the market place.   So if your friend decides to move forward and discontinue using clonipine they should do so under a well managed and carefully outlined plan by thier health care provider team.