- Mar 2019
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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We have previously shown that antinociceptive effects of morphine are enhanced in histamine H1 receptor gene knockout mice.
H1 antihistamines enhance the opioid high in humans. Hospitals sometimes administer antihistamines in combination with opioids. It's not hard to find people online who are using this combination recreationally.
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- Jan 2019
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Local file Local file
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Table 1. Analgesic potency of nalorphine compared with morphine for postoperative pain*
2 mg appears most effective. download PDF here.
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- Sep 2018
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Analgesia obtained when 10 mg of morphine was combined with 100 mg of hydroxyzine was significantly superior to that obtained with morphine alone.
It is interesting to note that they report potentiation of 10mg but not 5mg of morphine. Thus, it is possible that antihistamine potentiation is dependent on dose of opioid, or that antihistamines raise the analgesic ceiling. That is to say, antihistamines may raise the maximum possible effect from opioids without raising the effects of lower doses much. However, antihistamine combination did tend to enhance the effects of lower dose morphine, but the effect was not as dramatic (therefore not reaching statistical significance in a study of this power).
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- Aug 2018
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www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
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Prazosin had no analgesic effect alone but dose-dependently potentiated morphine analgesia in morphine-naive mice. Another alpha(1)-adrenoceptor antagonist, corynanthine, had similar effects. Prazosin also increased the analgesic potency of the morphine test dose in morphine-tolerant mice. Naloxone-precipitated vertical jumping was not affected, but weight loss was reduced by prazosin. Acutely administered clonidine potentiated morphine analgesia and alleviated opioid withdrawal signs, as expected. We conclude that in addition to the already established involvement of alpha(2)-adrenoceptors in opioid actions, also alpha(1)-adrenoceptors have significant modulatory role in opioid analgesia and withdrawal.
This is interesting but not exactly surprising, given that both are depressants. What is surprising, however, is the contrast between this and the fact that stimulants also enhance morphine analgesia.
Potentiation of Opioid Analgesia by Psychostimulant Drugs: A Review00084-0/fulltext)
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