04-12-2012, 02:59 AM
The T1/2 (half-life) of a drug you are correct that reflects the time a body requires to eliminate (or deactivate is better representation of what actually happens) 1/2 of the drug from your system.
Here are some important things to take into consideration when looking at T1/2:
1. You need to know what the ED50 (effective dose in 50% of the population is)
2. You need to know what the LD50 (lethal dose in 50% of the population) is)
3. The spread between the ED50 and LD50 will provide you with an indication of the safety profile of the drug. If it`s a narrow therapeutic drug that difference between the LD50 and ED50 will be smallish and the dose that is effective and can be lethal is very close to one another and you need to be very careful on controlling the dosage..
4. You need to understand whether maintaining a steady-state concentration of the drug is desirable (the blood levels are maintained in a narrow band) - as is the case with Antibiotics to ensure a proper and effective kill rate of pathogens or if it should be dosed in a classic bell curve where it rises and falls giving your body a chance to rest which is typically 3x the half-life. For a 4hr t1/2, you would be prescribed 2x BID (twice a day) or every 12 hours.
5. Steady State: If you dose the drug at the half-life, after 5 doses, you`ll achieve steady whereby the plasma levels of the drug hardly change over the duration of the half-life.
6. Loading Dose: If you dose 2x the normal dose the 1st time, you decrease the amount of time it takes to his steady-state. Normally only need for a very fast elimation rate and need to hit steady-state fast (removal of a pathogen).
7. After 6-7 half-lifes (upon ending dosing), the drug is effectively removed from your system as you would have cleared over 99% of the drug and has no biological effect.
With hormones, from what I understand you do not want to be hitting steady-state and dosing on the half-life as you will cause several negative feedback loops and cause a cascade of hormonal responses that will have very negative consequences. That being said - there is probably very very few doctors or research papers are available on the effects of high constant levels of female hormones in biological males. I would guess that it would lead to several estrogen cancer concerns, a lose of sex drive, significant atrophy of testis and penis and probably a negative cognitive effect as well (decreased attentation etc.)
Here are some important things to take into consideration when looking at T1/2:
1. You need to know what the ED50 (effective dose in 50% of the population is)
2. You need to know what the LD50 (lethal dose in 50% of the population) is)
3. The spread between the ED50 and LD50 will provide you with an indication of the safety profile of the drug. If it`s a narrow therapeutic drug that difference between the LD50 and ED50 will be smallish and the dose that is effective and can be lethal is very close to one another and you need to be very careful on controlling the dosage..
4. You need to understand whether maintaining a steady-state concentration of the drug is desirable (the blood levels are maintained in a narrow band) - as is the case with Antibiotics to ensure a proper and effective kill rate of pathogens or if it should be dosed in a classic bell curve where it rises and falls giving your body a chance to rest which is typically 3x the half-life. For a 4hr t1/2, you would be prescribed 2x BID (twice a day) or every 12 hours.
5. Steady State: If you dose the drug at the half-life, after 5 doses, you`ll achieve steady whereby the plasma levels of the drug hardly change over the duration of the half-life.
6. Loading Dose: If you dose 2x the normal dose the 1st time, you decrease the amount of time it takes to his steady-state. Normally only need for a very fast elimation rate and need to hit steady-state fast (removal of a pathogen).
7. After 6-7 half-lifes (upon ending dosing), the drug is effectively removed from your system as you would have cleared over 99% of the drug and has no biological effect.
With hormones, from what I understand you do not want to be hitting steady-state and dosing on the half-life as you will cause several negative feedback loops and cause a cascade of hormonal responses that will have very negative consequences. That being said - there is probably very very few doctors or research papers are available on the effects of high constant levels of female hormones in biological males. I would guess that it would lead to several estrogen cancer concerns, a lose of sex drive, significant atrophy of testis and penis and probably a negative cognitive effect as well (decreased attentation etc.)