Buprenorphine vs. morphine via the epidural route: A controlled comparative clinical study of respiratory effects and analgesic activity

Abstract

Twelve patients with intense or very intense pain of the non-incident type, secondary to neoplasia, were divided at random into two groups and treated with an epidural dose of 3 mg of morphine in 10 ml of glucose solution (6 patients = group M) or with 0.3 mg of buprenorphine in the same vehicle (6 patients = group B). None of the patients had previously been treated with opioids by any route. After first determining basal values, the following assessments were carried out: (1) evaluation of the analgesic effect of the drugs with checks at 30 min and at 1, 2, 3, 4, 6 and 18 h after administration, using a visual analogue scale, a numerical rating scale and a simple descriptive scale; and (2) evaluation of effects on respiration by means of checks at 30 and 90 min and at 6 and 18 h, on control of breathing indices (P0.1; VE; VA; Ti/Ttot; VT/Ti; RR), gas exchange indices (delta(A-a)O2; VD/VT; pAO2; R) and blood gas and acid-base indices (paO2; paCO2; pH; HCO3-). The data obtained were analyzed statistically using analysis of variance and Student's t test. The study results showed very similar analgesic efficacy for both treatments at a single dosage level of morphine (3 mg) compared to buprenorphine (0.3 mg), which was approximately 3 times greater than an equivalent parenteral dose of morphine (10 mg). Analysis of the results revealed statistically, though not clinically, significant changes in respiratory function indices, only in the buprenorphine-treated group. The effects of buprenorphine on respiratory function, when administered epidurally at the above dosage, are less favourable than those of morphine in the early measurements, probably because of its greater systemic absorption; nevertheless, the risk of delayed respiratory depression appears to be less after buprenorphine than after morphine.

Buprenorphine Reduces Cerebral Glucose Metabolism in Polydrug Abusers

“…Consistent with the respiratory depressant proper ties of opioid agonists (Jaffe and Martin 1990) and previ ous studies with buprenorphine (e.g., Pasqualucci et al 1987), buprenorphine reduced respiration, as reflected in reductions of respiratory rate and Pa02 and increases in Pac02' It seems unlikely, however, that the decre ments in rCMRglc and CMRglc reported here could be due to the mild hypoxia that was produced. First, ex treme hypoxia can elevate CMRglc (28% for Pa02 = 34.6 mm Hg) (Cohen et al 1967) by stimulating anaerobic glycolysis (Siesj61978).…”

Buprenorphine in cancer pain

“…Buprenorphine has octanol-water partition coefficient ranges between 2320-1213 compared to morphine, which is 1.42 [39,60]. Buprenorphine has almost double the molecular weight of morphine and is highly protein bound (96%).…”

“…Buprenorphine has almost double the molecular weight of morphine and is highly protein bound (96%). Buprenorphine has the same lipophilic characteristics of fentanyl [60]. It is distributionextensive into tissues and is highly sequestered in the central nervous system (CNS) and liver.…”

“…However, the physicochemical characteristics of buprenorphine, like fentanyl, are such that there is rapid systemic absorption, and thus, buprenorphine is not regionally confined. Epidural buprenorphine is associated with the early onset of respiratory depression when compared to epidural morphine and will have little advantage over systemic administration [60].…”

“…A statistical, but not clinically significant, early respiratory depression was seen with buprenorphine. This was due to buprenorphine's rapid systemic absorption [60].…”