Is it effective at all?
The only thing I've found on the topic is that spiro causes sores and tastes bad, and another thing in broken english that said 'taking spiro sublingually/buccally is a good way to bypass the low bioavailability of spiro', but it was very hard to read and I don't know if its reliable
I wouldn't try it personally. First and foremost it is a diuretic and blood pressure medication. If sublingual administration is even possible and you do increase bioavailability you could be putting yourself at risk.
Secondly the taste is just horrible.
If you are concerned that the spiro isn't doing its job, it's best to talk to you doctor about checking your levels and adjusting the prescribed dosage.
Bleh! The thought of the taste in my mouth for that long would be the end of it for me!
On the metabolism and half life though, no idea. Most medications that have high "first pass" metabolism by the liver are designed as sublingual or not oral to avoid it. I have heard of people having half dose spiro in the morning and half a night (ie. instead of 100mg in the morning only, 50mg in the morning and 50mg at night), which would technically give you a more continuous level in your blood rather than a peak and trough from a daily dose, but I'm not a doctor.
Speak with your GP or Endo but as with most things medication wise I don't think there is enough research out there to say one way or another.
Again, spiro sublingually or buccally just sounds awful! :P
My understanding is both Spiro and Finesteride taken sublingual is dangerous. Check with your doc before trying that. Estrogen is the one commonly taken sublingual. Again check with the doc they have a need to know or your blood serums could be scewed or misinterpreted.
Enjoy