Probably the hardest part of using phenobarbital is the fact it can be used in many ways, which leads to confusion about what’s the “right” way. Let’s take a look at its many use cases.
1. As monotherapy—instead of using benzos alone, you instead use phenobarbital alone. However, as long as you use the same caution as you always do when you combine two similar agents (ie two sedatives like fentanyl and a benzo, or even ketorolac with ibuprofen), you can use both. But as pointed out yesterday, you should titrate only one agent at a time so you know what’s causing what.
2. As a “load” of 10 mg/kg in one go. The benefit of this is to reduce ICU upgrade—so its most beneficial use case is in people who you are admitting to the hospital. Some intrepid souls I know will give this to people who they’re discharging, and find they tolerate it well when their history firmly supports a high tolerance level; however, if you’re not quite to that level of comfort, then definitely try it in that patient you’re admitting who is withdrawing actively and has a severe history. You may save them from the ICU!
3. As symptom-triggered spot dosing—ie exactly the same way you would use benzos. For the person in mild withdrawal that you would give 1-2 mg lorazepam to, you could instead give 130 mg phenobarbital; you might find they respond extremely well, more sensitively than they would to benzos. This is because we know that people get benzo-resistant over time (eg why you can give 10 mg lorazepam to someone and it barely touches them).
4. As a scheduled taper, much like a scheduled Librium taper. This is primarily an advantage when a patient is inpatient, and can avoid the need for breakthrough dosing. You could consider giving an oral dose of phenobarbital to the same patient you feel is appropriate for a discharge script of Librium or gabapentin. Literature however does not yet exist demonstrating outpatient benefits of phenobarbital over benzos, so generally this will remain an inpatient/ED intervention for now.
5. A combo of the above! People can absolutely get a load and then still need some spot dosing—just depends on how high their tolerance is and how far along they are in their withdrawal syndrome. You can also give a load, and then if the patient stays stable, they can be put on a scheduled taper (much like after getting a bunch of IV benzos, someone can be put on a Librium taper).
As much confusion as this can cause, the upshot is that when it comes to phenobarbital, there’s actually quite a lot of freedom. This is actually a strength and not a weakness—but like any tool, it should be used mindfully, with a deliberate goal.