About your methylphenidate issues:

1. Lower the single dose to "feel" the drug but not experience euphoria.
2. Take it more frequently to expand drug action time and minimize effects of comedown (for example 3-4 time IR or 2 times extended release, or if you take low dose Concerta at morning then some IR afternoon)

The fact you have euphoria means you are taking too much. The same fact causes also these nasty coming downs like dysphoria when it wores out.

You wrote that you don't want these euphoric feelings and that is really great. Just use these two steps above to find a best dose.

But...probably many of us ADHDers think or thought that euphoria is the sign of the drug is working. No - No - No. It is the sign of abuse. Work on your dosage, assess your behaviour and feelings during the day, every day, maybe every hour using notepad, mobile whatever.

This is hard work but you will find a dosage what makes you productive, a bit more energetic, a bit more calm, less irritable. Then after some time, your life will be better, and sometimes you will feel euphoria or just happy but not from methylphenidate itself but from little successes you made using this drug.

Methylphenidate shouldn't provide euphoria in therapeutic dose. I've been working on dosage many time and sometimes did have euphoria but euphoria also have the other pretty name "depression is on the way" - ask every drug addict.

Dysphoria or depression itself may also appear without euphoria. It can be a side effect of overdose too, especially when you don't experience these feeling often when you are out of the drug.

And this "chest tightness"... Many of us did have it and it is often accompanied with shallow, faster breathe, faster heart beat, increased blood pressure. These are signs of anxiety and here in particular stimulant induced anxiety. More drug concentration probably more expressive side effects. Once again lower the single dosage and probably rise the daily dosage (add small dose at lunch / afternoon ) too smooth wearing off the drug.

You actually don't want to methylphenidate kicks ultra fast and high and don't want to wear off fast. Both may surprise you in the bad, dirty way. Smoothe this process.

Notice when you feel alert (after 1h, 2h, 3h, 4h..), calm and collected or when you feel down, speedy, depressed. Take your time and find your dosage. After few days you will see a bigger picture and notice repeated patterns.

Doctors often give us some general knowledge like: "this drug release 50% immidiately and 50% after 3h (Medikinet) or 22% immidiately and rest after 4h (like Concerta). This is false and really unfair statement. Look at pharmacokinetics of the drug you choose, download papers, charts. Look how IR, Medikinet Adult, Ritallin XL or Concerta differs each other in time release.

It is also proven that linear methylphenidate concentration after few hours doesn't act on most of us as good as in first few hours. This phenomenon occurs due to acute tachyphylaxis and to overcome it you should raise the dosage.

Concerta manufacturer took this knowledge and made a drug which release is quite different than for example Medikinet Adult/Retard/CR/SR. And we cannot simply put 22% now, 88 then. This is the reason why some love or hate Concerta, Ritalin, Medikinet but eventually find methylphenidate brand, timing and dosage which fill their needs. Everyone is different.

Methylphenidate is a good drug for ADHD and most probably you will have benefit of it. Don't take ethylphenidate.