In the Caraka Saṃhitā, cikitsāsthāna, 23, vv. 90–94, the one who prepares the antidote to poison called Mahāgandhahastin should utter the following mantra:

While grinding [the ingredients] one should pronounce this siddha mantra:
“My mother is called jayā, my father jaya (victory). I, the son of jaya and jayā, am victorious (or: “I am Vijaya”) and win.
Praise to Viṣṇu Narasiṃha, Viśvakarman, Sanātana, Kṛṣṇa, Bhava and Vibhava. I bestow (or: “I restrain”) the splendour of Vṛśākapi and the direct splendour of Brahmā and Indra
Just like ‘I don’t know the defeat of Vāsudeva, nor the marriage of my mother, nor the draining of the ocean’, so, through this truthful statement may this antidote be successful.
O, best among the medications, mixed with Hilimili, may you protect [me], hail!”

piṣyamāṇa imaṃ cātra siddhaṃ mantram udīrayet |
mama matā jayā nāma jayo nāmeti me pitā ||
so ’haṃ jayajayāputro vijayo ’tha jayāmi ca |
namaḥ puruṣasiṃhāya viṣṇave viśvakarmaṇe ||
sanātanāya kṛṣṇāya bhavāya vibhavāya ca |
tejo vṛṣākapeḥ sākṣāt tejo brahmendrayor yame ||
yathāhaṃ nābhijānāmi vāsudevaparājayam |
mātuś ca pāṇigrahaṇaṃ samudrasya ca śoṣaṇam ||
anena satyavākyena siddhyatām agado hy ayam |
hilimilisaṃspṛṣṭe rakṣa sarvabheṣajottame svāhā ||

Now, the general sense of the mantra is clear, but some aspects of it remain obscure to me. For instance, it is not clear whether Puruṣasiṃha, Viśvakarman, Sanātana, etc. are attributes of Viṣṇu or separate deities. The form yame is also not what one would have expected, given that yam– belongs to the first verbal class.

Another group of problems is connected with the vocatives in the last line. Why should one find at once feminine forms?

I checked in M. Slouber’s very informative PhD thesis (which then became a book) and he translates the passage as follows:

I am Vijaya, the son of Jaya and Jayā, and I am victorious. Homage to Viṣṇu the man- lion, to Visvakarman, to Sanatana, to Kṛṣṇa, to Bhava and Vibhava. The energy of Vṛśākapi embodied, the energy of the twins Brahma and Indra. As surely as I do not know the defeat of Vāsudeva, a mother’s marriage, nor the drying up of the ocean—by that true statement let this antidote be effective. HILI MILI protect [me while making] this most excellent of all medicines.

Notice his translation of yame as “twins”. On hilimili he adds elswehere (pp. 16–17 of his PhD thesis) an interesting remark:

hili mili are important words in mantras that are transitional between Vedic and later Mantramārga usage. The Mahāmāyūrīvidyārājñī, for example, uses these words extensively and says they are of Dravidian origin. Other scholars think they may be related to Middle Indic imperatives (Skt. √hṛ and √mṛ). In some Apabhraṃśa dialects the second person singular imperative does take the ending “i.” It is highly improbable that the words are nonsense; rather, it is our own ignorance of ancient Indic languages that makes them seem so.

Slouber does not discuss the shift to feminine forms in the last line (where he translates “hilimili” as the subject) and it might be worth noticing that bheṣaja ‘medicine’ is a neuter term.

I am endebted to him because on the same page of his PhD thesis he mentions the version of the mantra found in Vāgbhaṭa’s Aṣṭāṅgahṛdaya. The Aṣṭāṅgahṛdaya is a later (7th c.?) text, clearly dependent on the Caraka and Suśruta Saṃhitā, but in this case it may preserve an older tradition, since the feminine forms make sense in its context:

Praise to Narasiṃha and praise to Nārāyaṇa. Just like one does not know the defeat in battle of Kṛṣṇa, through this truthful statement may my antidote be succesful.
Praise to the Mother of Beryl, hulu hulu, protect me from all poisons! Gaurī, Gandhārī, Cāṇḍalī, Mātāṅgī, hail!

namaḥ puruṣasiṃhāya namo nārāyaṇāya ca |
yathasau nābhijānāti raṇe kṛṣṇaparājayam ||
etena satyavākyena agado me prasidhyatu |
namo vaiḍūryamāte hulu hulu rakṣa māṃ sarvaviṣebhyaḥ |
gauri gāndhāri cāṇḍāli mātāṅgi svāhā […] || (Aṣṭāṅgahṛdaya 6,35.28–30)

In this context, the feminine endings make sense, so much that I am tempted to think that even the mantra as found in the Carakasaṃhitā presupposes feminine deities. What do readers think about these vocatives? And do they have any better idea about the yame?