Insel's word in W&F made me go LIU, to see if I remembered correctly what drug it was. Gurunet says:
lau·da·num (lôd'n-əm)
n.
A tincture of opium, formerly used as a drug.

[New Latin, perhaps alteration of Medieval Latin labdanum, labdanum. See labdanum.]

I wondered about tincture; M-W has:
Main Entry: 1tinc·ture
Pronunciation: 'ti[ng](k)-ch&r
Function: noun
Etymology: Middle English, from Latin tinctura act of dyeing, from tinctus, past participle of tingere to tinge
1 a archaic : a substance that colors, dyes, or stains b : COLOR, TINT
2 a : a characteristic quality : CAST b : a slight admixture : TRACE
3 obsolete : an active principle or extract
4 : a heraldic metal, color, or fur
5 : a solution of a medicinal substance in an alcoholic menstruum

THEN, I had to LU that last word! Gurunet:
men·stru·um (mĕn'strū-əm)
n., pl. -stru·ums or -stru·a (-strū-ə).
A solvent, especially one used in extracting compounds from plant and animal tissues and preparing drugs.

[Middle English, menstruation, from Medieval Latin mēnstruum, sing. of Latin mēnstrua, menses. See menstruate.]


But all this effort (!) still didn't answer my question satisfactorily: I feel sure that I've read that laudanum came in powdered form; yet the def. said tincture, and I thought tincture meant liquid. Does anyone know how laudanum was administered?