SGDI 15632 (Teos, c. 475 BCE; from Buck, Greek Dialects: Ionic Inscriptions, 3)
“Who ever should make deadly drugs for the Teian community or for an individual, destroy him and his family. Whoever stops the importation of grain into the Teian land or repels it as it is being imported either with skill or device and on sea or on land, destroy him and his family.”
Aristotle (On Plants) and Galen (varia) define deleterious medicines (δηλητήρια φάρμακα) as those that are fatal to human beings, such as poisonous venom or substances coming from hemlock (or concentrations of opium, henbane etc.). Of course, such things are weaponized fairly early in human history as this threatening inscription above from Teos illustrates.
Scholia bT ad Il. 1.594
“[The Sintian men}: Philokhoros says that because they were Pelasgians they were called this because after they sailed to Brauron they kidnapped the women who were carrying baskets. For they call “harming” [to blaptein] sinesthai.
But Eratosthenes says that they have this name because they are wizards who discovered deadly drugs. Porphyry says that they were the first people to make weapons, the things which bring harm to men. Or, because they were the first to discover piracy.”
Σίντιες ἄνδρες] Φιλόχορός φησι Πελασγοὺς αὐτοὺς ὄντας οὕτω προσαγορευθῆναι, ἐπεὶ πλεύσαντες εἰς Βραυρῶνα κανηφόρους παρθένους ἥρπασαν· σίνεσθαι δὲ τὸ βλάπτειν λέγουσιν. ᾽Ερατοσθένης δέ, ἐπεὶ γόητες ὄντες εὗρον δηλητήρια φάρμακα. ὁ δὲ Πορφύριος, ἐπεὶ πρῶτοι τὰ πολεμιστήρια ἐδημιούργησαν ὅπλα, ἃ πρὸς βλάβην ἀνθρώπων συντελεῖ· ἢ ἐπεὶ πρῶτοι ληιστήρια ἐξεῦρον.
Herodian, 3. 5
“He also gave them some deadly drugs to give to him in secret if they were able to persuade some of the cooks or waiters, even though [Albinus’] friends were suspicious and advising him to safeguard himself against a deceptively clever adversary.”
ἔδωκε δὲ αὐτοῖς καὶ δηλητήρια φάρμακα, ὅπως τινὰς πείσαιεν, εἰ δυνηθεῖεν, ἢ τῶν ὀψοποιῶν ἢ τῶν πρὸς ταῖς κύλιξι, λαθεῖν καὶ ἐπιδοῦναι αὐτῷ <καίτοι> ὑποπτευόντων τῶν περὶ αὐτὸν φίλων καὶ4 συμβουλευόντων αὐτῷ φυλάττεσθαι ἄνδρα 6ἀπατεῶνα σοφόν τε πρὸς ἐπιβουλήν·