1. Gastrointestinal/enteral
Administration through the gastrointestinal tract is sometimes termed enteral or enteric administration (strictly meaning 'through theintestines'). Enteral/enteric administration usually includes oral[3] (through the mouth) and rectal (into the rectum)[3] administration, in the sense that these are taken up by the intestines. However, uptake of drugs administered orally may also occur already in the stomach, whygastrointestinal (along the gastrointestinal tract) may be a more fitting word for this route of administration. Furthermore, some application locations often classified as enteral, such as sublingual[3] (under the tongue) and sublabial or buccal (between the cheek and gums/gingiva), are taken up in the proximal part of the gastrointestinal tract without reaching the intestines. Strictly enteral administration (directly into the intestines) can be used for systemic administration, as well as local (sometimes termed topical), such as in enema where e.g. contrast media is infused into the intestines for imaging. However, in the classification system basically distinguishing substances by location of their effects, the term enteral is reserved for substances with systemic effects.
Many drugs as tablets, capsules, or drops are taken orally. Administration methods directly into the stomach include those by gastric feeding tube or gastrostomy. Substances may also be placed into the small intestines, as with a duodenal feeding tube and enteral nutrition.Some enteric coated tablets will not dissolve in stomach but it is directed to the intestine because the drug present in the enteric coated tablet causes irritation in the stomach.
2. Central nervous system
 epidural (synonym: peridural) (injection or infusion into the epidural space), e.g. epidural anesthesia
 intracerebral (into the cerebrum) direct injection into the brain. Used in experimental research of chemicals[4] and as a treatment for malignancies of the brain.[5] The intracerebral route can also interrupt the blood brain barrier from holding up against subsequent routes.[6]
 intracerebroventricular (into the cerebral ventricles) administration into the ventricular system of the brain. One use is as a last line of opioid treatment for terminal cancer patients with intractable cancer pain.[7]
3. Other locations
 epicutaneous (application onto the skin). It can be used both for local effect as in allergy testing and typical local anesthesia, as well assystemic effects when the active substance diffuses through skin in a transdermal route.
 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. Skin popping is a slang term that includes this method of administration, and is usually used in association 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.[8]
 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