Recommendations on whether and when to discontinue PEP after missed doses is largely empirical, informed by the biological and pharmacological properties of each agent, as well as expert opinion. Advice provided to those who miss dose(s) will depend on both the time since the last dose, as well as the number of missed doses. Maintenance of therapeutic levels of PEP differ due to varying pharmacokinetic properties of each PEP agent68,94,95
What to advise patients who miss PEP dose(s):
- Take the next dose as soon as possible, unless it is time for the next dose
- If it is time for next dose, skip the missed dose and return to regular schedule
- Do not take a double dose to make up for a forgotten dose
- if 72 hours or more has elapsed since the last dose, discontinue PEP
- if interruption of PEP (for less than 72 hours since the last missed dose) is related to side-effects, seek urgent specialist advice
- depending on the likelihood of which agent is most likely to be causing specific side-effects, advice may be to stop the third drug and continue two-drug PEP or consider alternative agents.