mainline

To inject (an illegal or addictive drug, such as heroin) directly into a major vein.

To inject a drug intravenously.

Being in a principal or well-established position.

to inject (illegal drugs) into the vein.

normal, principal or standard.

Of or pertaining to the principal route or line of a railway

Of or pertaining to a surface railway as distinct from an underground, elevated or light rail one.

To inject (a drug) directly into a vein.

inject into the vein