Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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    B Drugs
    Alphabetical Drug Summaries
    Dr. Bob Stein


a)      This is the name of the family of drugs that includes diazepam, midazolam, and zolazepam



a)      Classification

i)        Local anesthetic

b)      General Information

i)        Slower onset of action (20 - 30 minutes) but longer duration of effect (3 -5 hours) when compared to lidocaine

(1)   Combine with either 0.075 mg/kg (0.035 mg/lb) morphine or 0.003 mg/kg (0.0015 mg/lb) buprenorphine to extend the analgesic duration of local blocks to approximately 20 hours [1],[2]

(2)   Epidural effect is longer

ii)       With local anesthetics, volume is more important than concentration

(1)   Dilute with sterile water when blocking larger areas

(a)    Commonly diluted to 50% to 33% bupivacaine (1:1 to 2:1 ratio of sterile water to bupivacaine)

c)      Advantages/Recommended use

i)        Local nerve blocks

ii)       Epidural anesthesia

(1)   May cause a lengthy motor block

iii)     Intra-articular after joint closure

d)      Cautionary Information

i)        More potential for toxicity than lidocaine

(1)   Calculate doses very carefully

(2)   Never administer IV

(3)   Toxic signs can be CNS or cardiac

(a)    Cardiac toxicities are potentially fatal

(4)   There is some debate about the use of intrapleural bupivacaine if a pericardiectomy has been performed due to the increased potential for cardiac toxicity

e)      Dosage Information

i)        Local blocks

(1)   Dog - generally 1.0 mg/kg up to a maximum dose of 2 mg/kg (1 mg/lb)

(2)   Cats – maximum of 1.0 mg/kg (0.5 mg/lb)

ii)       Intra-articular

(1)   Generally whatever will fit after joint closure

(a)    Dogs - up to the maximum of 2 mg/kg (1 mg/lb)

(b)   Cats – up to the maximum of 1 mg/kg (0.5 mg/lb)

iii)     Epidural

(1)   Dogs and Cats – 1 mg/kg (0.5 mg/lb)

iv)     Other uses

(1)   Intercostal blocks

(2)   Brachial plexus blocks

(3)   Ring blocks

(4)   Dental Blocks

f)       Cost

i)        Moderate



a)      Classification

i)        Opioid

(1)   Partial mu agonist of extremely high affinity

(2)   Some kappa antagonism

(3)   Class III

b)      General Information

i)        Good all around analgesic for mild to moderate pain free of any expected undesirable effect

(1)   Anecdotal reports of dogs receiving 0.2 mg/lb IV on a QID basis for several doses without negative consequences (M. Richey, DACVA)

ii)       Minimal, if any, sedative effect

iii)     Buprenorphine has a delayed onset

(1)   30 minutes to peak effect when given IV

(2)   45 to 60 minutes to peak effect when given IM

iv)     Duration of effect is influenced by dose

(1)   3 to 4 hours at 0.010 mg/kg (0.005 mg/lb) dose

(2)   6 to 8 hours at 0.020 mg/kg (0.010 mg/lb) dose

(3)   8 to 10 hours at 0.030 mg/kg (0.015 mg/lb) dose

(4)   10 to 12 hours at 0.040 mg/kg (0.020 mg/lb) dose

c)      Advantages/Recommended use

i)        General soft tissue surgery

ii)       Light orthopedic surgery

iii)     In cats, studies have shown that bioavailability is the same whether given IV, IM, or via buccal oral mucosa (bioavailability is poor from GI tract – give sublingually or in lateral cheek pouch)

(1)   This transmucosal absorption is influenced by the alkaline pH of feline saliva

(a)    There is, as yet, no support for effective oral absorption by the dog

(2)   Excellent option for home analgesic management in cats

d)      Cautionary Information

(1)   Difficult to reverse if undesirable effects arise

(2)   Would be expected to antagonize other pure mu agonists like morphine, hydromorphone, fentanyl, and oxymorphone

e)      Dosage Information

(1)   Dogs – 0.010 to 0.040 mg/kg (0.005 – 0.02 mg/lb) IM or IV

(2)   Cats - 0.010 to 0.040 mg/kg (0.005 – 0.02 mg/lb) IM, IV, or Tramsmucosally

f)       Cost

i)        Moderate at low end of dose range - high at upper dose range



a)      Classification

i)        Opioid

(1)   A mixed agonist/antagonist with primary agonistic activity at the kappa receptor

(a)    Generally antagonistic at the mu receptor

b)      General Information

i)        Good all around analgesic for mild pain free of any expected undesirable effect

ii)       Little, or no respiratory depression at clinical doses

iii)     Duration of effect is 30 minutes to 1 hour in dogs and 1 to 3 hours in cats

c)      Advantages/Recommended use

i)        General soft tissue surgery

ii)       More effective for visceral (soft tissue) than somatic (orthopedic) analgesic

d)      Cautionary Information

i)        Short duration of effect

(1)   Dogs - 30 minutes to 1 hour

(2)   Cats - 1 to 3 hours

ii)       Higher doses can produce excitement and dysphoria

e)      Dosage Information

i)        Dog & Cats

(1)   0.2 to 0.4 mg/kg (0.1 to 0.2 mg/lb) IV, IM, SC

(a)    0.2 mg/kg (0.1 mg/lb) is the most commonly selected dose

f)       Cost

i)        Moderate (to high if given every few hours)

    Page References:

1 Buprenorphine added to the local anesthetic for axillary brachial plexus block prolongs postoperative analgesia. Candido KD, Winnie AP, Ghaleb AH, Fattouh MW, Franco CD: Reg Anesth Pain Med. 2002 Mar-Apr;27(2):162-7 


2 The addition of opioids to local anaesthetics in brachial plexus block: the comparative effects of morphine, buprenorphine and sufentanil. Bazin JE, Massoni C, Bruelle P, Fenies V, Groslier D, Schoeffler P: Anaesthesia. 1997 Sep;52(9):858-62

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