Is there a short-term, very strong anesthetic, which can be blocked/delayed by other substances?
Xenon. It is like an ideal anaesthetic. See here.


  Xenon is an interesting anesthetic as it appears to lack negative
  inotropicy and vasodilatation, giving great advantages to both
  patients with limited cardiovascular reserve or those who require
  hemodynamic stability. It has low toxicity and is not teratogenic.
  Xenon gives rapid induction and recovery, due to its low blood/gas
  partition coefficient (0.15), and has a MAC of 63%. Several vitro
  studies showed that Xenon may protect neural cells against ischaemic
  injury. Its low blood solubility can take to diffusion hypoxia if
  Xenon is not substituted by 100% oxygen at the end of anesthesia. It
  has been shown that, compared to other anesthetic regimens, Xenon
  anesthesia produces the highest regional blood flow in the brain,
  liver, kidney and intestine. In conclusion, the most important
  positive effects of Xenon are cardiovascular stability, cerebral
  protection and favourable pharmacokinetics. Negative points are high
  cost and the limited number of ventilators supplying Xenon.