Pharm 101: Oxycodone

• Explanation Alkalinisation of LA solutions → pH of injected solution more quickly approach that of normal tissue pH → faster formation of mixture with charged & uncharged forms → more rapid drug diffusion → quicker onset of nerve blocking
• Reference: https://www.nps.org.au/australian-prescriber/articles/alkalinisation-of-local-anaesthetic-solutions
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• Effect site concentration is the concentration of drug at the site of its biological activity, eg. bound to the receptors
• Effect site concentration is proportional to pharmacological effect, whereas plasma concentration may not be
• The rate of effect onset is determined by the rate of distribution of the drug from other compartments (i.e. central compartment) into the effect site.
• Reference: Deranged Physiology- Effect site equilibration

1. Respiratory minute ventilation increases
   • MV decreases – tidal volumes fall by ~25% in REM sleep compared with wakefulness.
2. Cerebral blood flow is comparable with wakefulness
   • CBF falls during NREM sleep – up to 22%. However CBF during REM sleep is similar to wakefulness.
3. The EEG shows high-voltage slow wave activity
   • MV decreases – tidal volumes fall by ~25% in REM sleep compared with wakefulness.
4. Episodes of REM sleep become progressively shorter as the duration of sleep increases
   • Periods of REM become longer throughout the night