If you want it to hit quick, all evidence leads to IM. I've been doin IM the last few days to avoid the site irritation. I did use sterile water today SC to see if it affected me the same as BW.
IMHO IM pwo is what I will be doin and Subq on nonlift days IF the sterile water works better for me.
Here's what I found... The absorption rate with SC injection is constant and slow enough to allow a sustained pharmacodynamic effect (Wilkinson, 2001). Blood supply in the SC area affects absorption, so the more proximal the capillaries are to the site of administration and the more numerous the capillaries, the faster the absorption of the drug. All drug products cross capillary membranes at a faster rate than they cross other tissue membranes (Ansel et al., 2004).
While drugs may be absorbed quickly following IM injection, the absorption rate depends on blood flow at the injection site. Joggers, who have greater blood flow to their legs, may experience a much faster rate of absorption of a drug injected into the thigh than if the same dose were injected into another muscle (Ansel et al., 2004; Wilkinson, 2001). The absorption rate of an aqueous drug administered in the deltoid or vastus lateralis generally is greater than that following injection into the gluteus maximus (Wilkinson, 2001). Blood flow to a muscle can affect the absorption rate of drugs administered by IM injection. Decreased blood flow can reduce the absorption rate (DeWit, 2001; Perry & Potter, 2004). In addition, the decreased muscle mass of many older adults may result in faster absorption of drugs delivered by IM injection (AstraZeneca Oncology, 2003; DeWit, 2001; Perry & Potter, 2004). IM absorption of some drugs in infants and young children may be unpredictable due in part to insufficient muscle tone and vascularity of muscle tissue.