Looking for the fast routes of absorption for meds?

Routes of administration are usually classified by application location (or exposition). The route or course the active substance takes from application location to the location where it has its target effect is usually rather a matter of pharmacokinetics (concerning the processes of uptake, distribution, and elimination of drugs). Nevertheless, some routes, especially the transdermal or transmucosal routes, are commonly referred to routes of administration. The location of the target effect of active substances are usually rather a matter of pharmacodynamics (concerning e.g. the physiological effects of drugs). Nevertheless, there is also a classification of routes of administration that basically distinguishes whether the effect is local (in "topical" administration) or systemic (in "enteral" or "parenteral" administration).

You need to mention the route of administration for absorption , there could be many:

Gastrointestinal/enteral
Central nervous system
* epicutaneous (application onto the skin).
* intradermal, (into the skin itself) is used for skin testing some allergens, and also for mantoux test for Tuberculosis
* subcutaneous (under the skin), e.g. insulin, a slang term for this method of administration is skin popping (usually done with recreational drugs)
* nasal administration (through the nose) can be used for topically acting substances, as well as for insufflation of e.g. decongestant nasal sprays to be taken up along the respiratory tract. Such substances are also called inhalational, e.g. inhalational anesthetics.
* intravenous (into a vein), e.g. many drugs, total parenteral nutrition
* intraarterial (into an artery), e.g. vasodilator drugs in the treatment of vasospasm and thrombolytic drugs for treatment of embolism
* intramuscular (into a muscle), e.g. many vaccines, antibiotics, and long-term psychoactive agents. Recreationally the colloquial term 'muscling' is used.
* intracardiac (into the heart), e.g. adrenaline during cardiopulmonary resuscitation (no longer commonly performed)
* intraosseous infusion (into the bone marrow) is, in effect, an indirect intravenous access because the bone marrow drains directly into the venous system. This route is occasionally used for drugs and fluids in emergency medicine and pediatrics when intravenous access is difficult.
* intrathecal (into the spinal canal) is most commonly used for spinal anesthesia and chemotherapy
* intraperitoneal, (infusion or injection into the peritoneum) e.g. peritoneal dialysis
* Intravesical infusion is into the urinary bladder.
* intravitreal, through the eye
* Intracavernous injection, an injection into the base of the penis
* Intravaginal, e.g. topical estrogens, antibacterials
* Intrauterine
* Extra-amniotic administration, between the endometrium and fetal membranes

Fast: 15–30 seconds for IV, 3–5 minutes for IM and subcutaneous (subcut)

One injection can be formulated to last days or even months, e.g., Depo-Provera, a birth control shot that works for three months.

Hope the info helps?