Buprenorphine Hydrochloride

Brand

Buprenex

Availability

Injectable: 0.324 mg (equivalent to 0.3 mg base/mL) in 1 mL ampules.

Pharmacology

Buprenorphine, a thebaine derivative, is a synthetic partial opiate agonist. It has some activity at the mu receptor which gives it a longer duration of analgesic action than butorphanol.

Buprenorphine is considered to be approximately 30 times stronger than morphine. However, morphine is a much stronger pain reliever due to the fact that morphine has more activity at the mu receptor. The duration of action may last from 8 to 12 hours. However, in rats, the duration of action is reported to be 6 hours, but may be prolonged in the presence of impaired liver function. ⁴²

Respiratory depression, decreased heart rate, and blood pressure are possible with this drug.

It is well absorbed IM, and SQ, and is metabolized in the liver. In rats, the drug concentrates in the liver, brain, gastrointestinal tract, and placenta. It is then excreted in urine, and via breast milk. While studies have not shown teratogenicity, there is not sufficient documentation at this time for safety in pregnant or lactating animals. It is, therefore, recommended to avoid giving in pregnant or lactating rats.

Indications

Used as an analgesic for pain relief with surgical procedures.

Drug Interactions or Contraindications

It is incompatible with diazepam and lorazepam.
Compatible drugs are acepromazine, atropine, diphenhydramine, droperidol, glycopyrolate, hydroxyzine, scopolamine, and xylazine.
If used with other central nervous system depressants such as anesthetic agents, antihistamines, phenothiazines, barbiturates and tranquilizers, may increase central nervous system and respiratory depression.
It is not recommended to give with MAO inhibitors.
Use with caution in respiratory compromise and impaired liver or renal function.

Adverse Reactions

CNS: sedation, confusion, lethargy, agitation.

CV: bradycardia

Resp: decreased respiratory rate

GI: pica, constipation

GU: urinary retention

Skin: itching

Other:

In the event there are signs of overdose such as cardiac and respiratory depression administer the following:

naloxone 0.01 to 0.1 mg/kg SC, IP (narcotic reversal) ¹^, ³⁴^, ⁴¹^, ⁴²
fluids
O2
vasopressors

Dosage Recommendations

0.1 mg/kg to 0.25 mg/kg, PO, q8hr to q12hr ⁴¹

or

0.02 mg/kg to 0.50 mg/kg , SQ , IP , IV, q6hr to q12hr ¹^, ²⁸

or

0.01 mg/kg to 0.05 mg/kg, SQ, IV, q8hr to q12hr ⁴¹

or

0.05 mg/kg to 0.1 mg/kg , SQ , q6hr to q12hr ²^, ³⁴^, ⁴²

Considerations

Important note to veterinarians: It has been reported that rats may develop pica after receiving this drug.¹^,²^,⁴
Be sure to instruct pet owners to monitor for this behavior if an opioid medication is given, and to contact vet immediately. Also have the pet owner remove the rat from any bedding source that might be chewed and ingested until medication has passed through the system. In severe cases it may be necessary to reduce or eliminate the drug from the rat’s system by providing warmed SQ or IV fluids. ²¹

It is also important to be aware that pica may be observed, in rats, where pain has not been adequately addressed.

*Note: per veterinary discretion, when discharging a rat to home postop, or for palliative care, injectable buprenorphine may be given, by needless syringe, to the buccal (to cheek tissue inside mouth) area.
Anecdotally: pet owners have noted less issue with pica at home when administered to the buccal area.
Store drug at room temperature.

References

Anesthesia and Analgesia in Laboratory Animals at UCSF. (2005, April 5). Retrieved December 20, 2008, from http://www.iacuc.ucsf.edu/Proc/awRatFrm.asp. Also, (2018, November ). Retrieved September 5, 2020, from https://larc.ucsf.edu/veterinary-information.
Clark, J., Myers, P., Goelz, M., Thigpen, J., & Forsythe, D. (1997). Pica behavior associated with buprenorphine administration in the rat. Lab Anim Sci, 47(3), 300-3.
Leach, M., Forrester, A., & Flecknell, P. (2010). Influence of preferred foodstuffs on the antinociceptive effects of orally administered buprenorphine in laboratory rats. Lab Anim., 44(1), 54-8.
Lee-Parritz, D. (2007). Analgesia for Rodent Experimental Surgery. Israel Journal of Veterinary Medicine, 62(3-4), 74-78. Retrieved December 20, 2008, from https://www.isrvma.org/article/62_3-4_2.htm.
Rat Analgesics. (n.d.). Retrieved December 20, 2008, from https://campusvet.wsu.edu/infofac/ratanalgesicsuse.htm. See: https://web.archive.org/web/20040823193416/https://campusvet.wsu.edu/infofac/ratanalgesicsuse.htm
Vogler, G. (2005). Anesthesia and Analgesia. In Suckow, M., Weisbroth, S., & Franklin, C. (Eds). The Laboratory Rat, Second Edition (American College of Laboratory Animal Medicine) (pp. 627-678). Toronto: Academic Press.
Takeda, N., Hasegawa, S., Morita, M., & Matsunaga, T. (1993). Pica in rats is analogous to emesis: an animal model in emesis research. Pharmacology, biochemistry, and behavior, 45(4), 817–821. https://doi.org/10.1016/0091-3057(93)90126-e