This paper is from 2010, but I'd like to draw attention to it as steady-state has been emphasized in threads about HRT.
Reference
Based on what I know about grapefruit kinetics in the liver, liver processing of some pharmaceuticals will be slowed for 24 hours. If you use tadalafil on-demand and you have grapefruit or juice, wait at least 24 hours before taking a dose.
Also, others on the forum have also suggested splitting the dosage of tadalafil and taking once every 12 hours. Compared to a single daily dose, this would raise the trough level, but lower the peak for a more regular plasma concentration.
Reference
Here are some things covered in this study:
- Steady state of tadalafil is reached after 5 days. This is probably why the Cialis website notes 4-5 days as being when you should see daily low dosages take effect.
- Steady-state tadalafil plasma concentration is 1.6 times higher than that of a single dose.
- Tadalafil 5mg once a day leads to a steady-state trough of 55 ng/mL, which corresponds to 90% PDE5 inhibition [style=font-style: italic;]in vitro[/style], which is the therapy standard likely to produce erections in most men.
- It is recommended to not consume grapefruit, especially when on a daily dose protocol. It slows the excretion of tadalafil. The study suggests either on-demand exclusively and avoiding grapefruit before taking it, or the lowest possible daily dose(2.5mg once daily).
Based on what I know about grapefruit kinetics in the liver, liver processing of some pharmaceuticals will be slowed for 24 hours. If you use tadalafil on-demand and you have grapefruit or juice, wait at least 24 hours before taking a dose.
Also, others on the forum have also suggested splitting the dosage of tadalafil and taking once every 12 hours. Compared to a single daily dose, this would raise the trough level, but lower the peak for a more regular plasma concentration.
