Possible Interaction: Amitriptyline and Capsaicin

“Results The higher doses of amitriptyline hydrochloride caused an increase in nociceptive behaviour (time spent in hindlimb withdrawal) on the formalin and capsaicin nociceptive tests, suggesting a potentiating effect.”

“Rationale We have previously shown that in rats, capsaicin (Cap) has antidepressant-like properties when assessed using the forced swimming test (FST) and that a sub-threshold dose of amitriptyline potentiates the effects of Cap.”

“Altogether, our results imply that low doses of capsaicin produce antidepressant-like effects, and enhance the effect of a subthreshold dose of amitriptyline in the FST.”

“Notably, doses of capsaicin (1 pg/kg, 1 ng/kg, and 0.001 mg/kg) that were ineffective when applied alone produced a significant decrease in immobility when combined with a subthreshold dose of amitriptyline (5 mg/kg).”

“Rats treated with capsaicin (0.01 mg/kg) + amitriptyline (5 mg/kg) displayed less immobility than those treated with a maximally effective dose of amitriptyline.”

“Conclusions: This study demonstrates that the combined application of amitriptyline and capsaicin results in prolonged cutaneous analgesia compared with amitriptyline alone, suggesting that the activation of the TRPV1 channel by capsaicin facilitates the passage of amitriptyline into nociceptors.”

“Here we examine whether the combined application of amitriptyline and capsaicin as a transdermal patch will produce prolonged cutaneous analgesia compared with amitriptyline alone.”

“Results: The cutaneous analgesic effect is significantly prolonged when amitriptyline is applied in combination with 8% capsaicin.”

“The mechanism that underlies the lesser skin irritation noted when amitriptyline is combined with higher doses of capsaicin compared with amitriptyline alone is unclear and may be related to a counteraction of amitriptyline-induced vasoconstriction.”

“Results: N-Methyl amitriptyline, amitriptyline , bupivacaine, or lidocaine, followed by injection of capsaicin 10 min later, each elicited a predominantly nociceptive-specific blockade.”

“Pretreatment of rats with capsaicin augmented the ability of amitriptyline to increase adenosine levels detected in the dialysis probe; it also enhanced tissue recovery of exogenously administered adenosine.”