While peyote use may be common knowledge, the lesser known San Pedro cacti - Trichocereus panachoi, T. peruvianius among others, have an equally ancient (if not longer) history intertwined with South American Indians of the central Andes. Archaeological finds dating to 1300 B.C. in Peru have turned up pottery depicting the shamanic use of Trichocereus cacti, although it was only identified as the principle entheogen of the mountainous central Andes about 40 years ago.
The cacti is made into a beverage called Achuma employed for religious, divinatory and healing use - which continues today. The shaman and/or the patient take the drink - the aim of the shaman in the curing ritual is to make the "patient bloom - to make the subconscious open like a flower."
The modern use of San Pedro cacti in Peru, Bolivia, Ecuador and parts of Chile today indicate it is truly an amalgam of shamanic and Christian elements. San Pero possibly obtained its name in the Christian belief that St. Peter holds the keys to the gates of heaven.
The drink is prepared generally by boiling the cactus for seven hours or more. Occassionally there are additives, althought many of the additives have still not been identified nor studied.
Like peyotes the various species of these cacti are rich in mescaline and phenylethylamines. Some varities such as T. terschekii also are rich in tryptamines, including the psychoactives NMT and DMT. The mescaline effects are obviously similar to peyote - at first one is drowsy or in a drean state and then one enters into a great visioning.