Doses - PENTOBARBITAL SODIUM
Note: In order to avoid possible confusion, doses used for euthanasia are listed separatelyunder the monograph for pentobarbital euthanasia solutions.Dogs:
As a sedative:
a) 2 - 4 mg/kg IV (Kirk 1986)
b) 2 - 4 mg/kg PO q6h (Davis 1985a)
For anesthesia:
a) 30 mg/kg IV to effect (Kirk 1986)
b) 10 - 30 mg/kg IV to effect (Morgan 1988)
c) 24 - 33 mg/kg IV (Booth 1988a)
For chemical restraint for ventilatory support:
a) 4 mg/kg initially IV; then 2 - 4 mg/kg/hr thereafter [Given concomitantly with oxymorphone: 0.2 mg/kg (up to 4.5 mg) IV; then 0.1 mg/kg every 2 hours thereafter](Pascoe 1986)
For post-myelographic seizures:
a) 2 - 4 mg/kg IV (to effect) (Walter, Feeney, and Johnston 1986)
For status epilepticus:
a) 5 - 15 mg/kg IV to effect (Morgan 1988)
b) 3 - 15 mg/kg IV SLOWLY to effect. Goal is heavy sedation, not surgical planes ofanesthesia. May need to repeat in 4-8 hours. (Raffe 1986)Cats:
As a sedative:
a) 2 - 4 mg/kg IV (Kirk 1986)
b) 2 - 4 mg/kg PO q6h (Davis 1985a)
For status epilepticus:
a) 5 - 15 mg/kg IV to effect (Morgan 1988)
b) 3 - 15 mg/kg IV SLOWLY to effect. Goal is heavy sedation, not surgical planes ofanesthesia. May need to repeat in 4-8 hours. (Raffe 1986)
For anesthesia:
a) 25 mg/kg IV, an additional 10 mg/kg IV may be given if initial dose is inadequate(Booth 1988a)Cattle:
a) 30 mg/kg IV to effect, repeat as needed for chlorinated hydrocarbon toxicity (Smith1986)
b) As an anesthetic in calves (over one month of age): 15 - 30 mg/kg IV (Thurmon and Benson 1986)
c) As a sedative in cattle: 1 - 2 grams IV in an adult cow (given until animal becomesunsteady and rear limb weakness occurs). 3 grams will usually induce recumbency.(Thurmon and Benson 1986)
Horses: Note: Pentobarbital is generally not considered an ideal agent for use in the adult horsedue to possible development of excitement and injury when the animal is "knocked down".
a) 3 - 15 mg/kg IV (Robinson 1987)
b) 15 - 18 mg/kg IV for light anesthesia (Schultz 1986)Swine:
a) 30 mg/kg IV to effect (Howard 1986)
b) As an anesthetic: 15 - 30 mg/kg IV (Thurmon and Benson 1986)Sheep:
As an anesthetic:
a) 20 - 30 mg/kg IV (Thurmon and Benson 1986)
b) Adult Sheep: 11 - 54 mg/kg IV (average dose 24 mg/kg IV). Anesthesia required forlonger than 15-30 minutes will require additional doses.
Lambs:15 - 26 mg/kg IV (will induce anesthesia for 15 minutes). Additional 5.5 mg/kg IV will give another 30 minutes of effect. (Booth 1988a)
Goats:
As an anesthetic:
a) 20 - 30 mg/kg IV (Thurmon and Benson 1986)
b) 25 mg/kg IV slowly, duration of satisfactory anesthesia will last only 20 minutes or so.(Booth 1988a)
Monitoring Parameters -1) Levels of consciousness and/or seizure control 2) Respiratory and cardiac signs 3) Body temperature 4) If using chronically, routine blood counts and liver function tests should be performed.
Client Information - This drug is best used in an inpatient setting or with close professional supervision. If dosage forms are dispensed to clients, they must be in instructed to keep away fromchildren and should be dispensed in child-resistant packaging.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times - Veterinary-Approved Products:
Pentobarbital Sodium for Injection 64.8 mg/ml (1 grain/ml) 100 ml vials
Generic; (Rx) Approved for use in dogs and cats.
Pentobarbital Sodium Oral Capsules; 50 mg, 100 mg capsules; (Rx)
Pentobarbital Sodium Rectal Suppositories; 30 mg, 60 mg, 120 mg, 200 mg in 12/pkg; (Rx)
A common trade name is Nembutal Sodium® (Abbott). May also be known as pentobarbitonesodium. Pentobarbital is a Class-II controlled substance and detailed records must be maintainedwith regard to its use and disbursement.
PENTOXIFYLLINE
Chemistry/
The commercially available tablets should be stored in well-closed containers, protected from lightand at 15-30°C. Pentoxifylline is also known as oxpentifylline or BL-191.
Pentoxifylline is postulated to reduce negative endotoxic effects of cytokine mediators via itsphosphodiesterase inhibition.
Uses, Indications - In horses, pentoxifylline has been used as adjunctive therapy for endotoxemiaand in the treatment of navicular disease. At the time of writing, the drug is still under investigationto document both safety and efficacy for these purposes.
Pentoxifylline has been used in dogs to enhance healing and reduce inflammation caused by ulcerative dermatosis in Shelties and Collies and for other conditions where improved microcirculation may be of benefit.
Pentoxifylline's major indications for humans include symptomatic treatment of peripheral vascular disease (e.g., intermittent claudication, sickle cell disease, Raynaud's, etc.) and cerebrovasculardiseases where blood flow may be impaired in the microvasculature.
Because of the wide interpatient variability, the authors were unable to make dosingrecommendations for clinical use.
In humans, pentoxifylline absorption from the gastrointestinal tract is rapid and almost complete, but a significant first-pass effect occurs. Food affects the rate, but not the extent of absorption.
While the distributive characteristics have not been fully described, it is known that the drug entersmaternal milk. Pentoxifylline is metabolized both in the liver and in erythrocytes and all identifiedmetabolites appear to be active.
Although safety in pregnant, lactating or breeding animals has not been established, studies inpregnant rats and rabbits demonstrated no overt teratogenicity. As pentoxifylline and its metabolitesenter maternal milk, benefits to the mother should be weighed against the risks to offspring.
Overdosage - Humans overdosed with pentoxifylline have demonstrated signs of flushing, seizures, hypotension, unconsciousness, agitation, fever, somnolence, GI distress and ECG changes.
One patient who ingested 80 mg/kg recovered completely. Overdoses should be treated using theusual methods of appropriate gut emptying and supportive therapies.
Ciprofloxacin (other quinolones too?) and cimetidine can increase pentoxifylline serum levels.
Increased adverse effects of pentoxifylline may result.
When pentoxifylline is used with warfarin or other anticoagulants, increased risk of bleeding mayresult. Use together with enhanced monitoring and caution. Theophylline blood levels may beincreased when used concurrently with pentoxifylline.
Dogs: 
As a sedative: a) 2 - 4 mg/kg IV (Kirk 1986)
b) 2 - 4 mg/kg PO q6h (Davis 1985a)
For anesthesia:
a) 30 mg/kg IV to effect (Kirk 1986)
b) 10 - 30 mg/kg IV to effect (Morgan 1988)
c) 24 - 33 mg/kg IV (Booth 1988a)
For chemical restraint for ventilatory support:
a) 4 mg/kg initially IV; then 2 - 4 mg/kg/hr thereafter [Given concomitantly with oxymorphone: 0.2 mg/kg (up to 4.5 mg) IV; then 0.1 mg/kg every 2 hours thereafter](Pascoe 1986)
For post-myelographic seizures:
a) 2 - 4 mg/kg IV (to effect) (Walter, Feeney, and Johnston 1986)
For status epilepticus:
a) 5 - 15 mg/kg IV to effect (Morgan 1988)
b) 3 - 15 mg/kg IV SLOWLY to effect. Goal is heavy sedation, not surgical planes ofanesthesia. May need to repeat in 4-8 hours. (Raffe 1986)
Cats: 
As a sedative: a) 2 - 4 mg/kg IV (Kirk 1986)
b) 2 - 4 mg/kg PO q6h (Davis 1985a)
For status epilepticus:
a) 5 - 15 mg/kg IV to effect (Morgan 1988)
b) 3 - 15 mg/kg IV SLOWLY to effect. Goal is heavy sedation, not surgical planes ofanesthesia. May need to repeat in 4-8 hours. (Raffe 1986)
For anesthesia:
a) 25 mg/kg IV, an additional 10 mg/kg IV may be given if initial dose is inadequate(Booth 1988a)
Cattle: 
a) 30 mg/kg IV to effect, repeat as needed for chlorinated hydrocarbon toxicity (Smith1986) b) As an anesthetic in calves (over one month of age): 15 - 30 mg/kg IV (Thurmon and Benson 1986)
c) As a sedative in cattle: 1 - 2 grams IV in an adult cow (given until animal becomesunsteady and rear limb weakness occurs). 3 grams will usually induce recumbency.(Thurmon and Benson 1986)
Horses: Note: Pentobarbital is generally not considered an ideal agent for use in the adult horsedue to possible development of excitement and injury when the animal is "knocked down".
a) 3 - 15 mg/kg IV (Robinson 1987)
b) 15 - 18 mg/kg IV for light anesthesia (Schultz 1986)
Swine: 
a) 30 mg/kg IV to effect (Howard 1986) b) As an anesthetic: 15 - 30 mg/kg IV (Thurmon and Benson 1986)
Sheep: 
As an anesthetic: a) 20 - 30 mg/kg IV (Thurmon and Benson 1986)
b) Adult Sheep: 11 - 54 mg/kg IV (average dose 24 mg/kg IV). Anesthesia required forlonger than 15-30 minutes will require additional doses.
Lambs:15 - 26 mg/kg IV (will induce anesthesia for 15 minutes). Additional 5.5 mg/kg IV will give another 30 minutes of effect. (Booth 1988a)
Goats:
As an anesthetic:
a) 20 - 30 mg/kg IV (Thurmon and Benson 1986)
b) 25 mg/kg IV slowly, duration of satisfactory anesthesia will last only 20 minutes or so.(Booth 1988a)
Monitoring Parameters -
Client Information - This drug is best used in an inpatient setting or with close professional supervision. If dosage forms are dispensed to clients, they must be in instructed to keep away fromchildren and should be dispensed in child-resistant packaging.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times - Veterinary-Approved Products:
Pentobarbital Sodium for Injection 64.8 mg/ml (1 grain/ml) 100 ml vials
Generic; (Rx) Approved for use in dogs and cats.
Human-Approved Products:
Pentobarbital Sodium for Injection; 50 mg/ml in 1 & 2 ml syringes, 2 ml, 20 ml and 50 ml vials;(Rx)Pentobarbital Sodium Oral Capsules; 50 mg, 100 mg capsules; (Rx)
Pentobarbital Sodium Rectal Suppositories; 30 mg, 60 mg, 120 mg, 200 mg in 12/pkg; (Rx)
A common trade name is Nembutal Sodium® (Abbott). May also be known as pentobarbitonesodium. Pentobarbital is a Class-II controlled substance and detailed records must be maintainedwith regard to its use and disbursement.
PENTOXIFYLLINE
Chemistry/
Storage, Stability, Compatibility
A synthetic xanthine derivative structurally relatedto caffeine and theophylline, pentoxifylline occurs as a white, odorless, bitter-tasting, crystallinepowder. At room temperature, approximately 77 mg are soluble in one ml of water and 63 mg inone ml of alcohol.The commercially available tablets should be stored in well-closed containers, protected from lightand at 15-30°C. Pentoxifylline is also known as oxpentifylline or BL-191.
Pharmacology
The mechanisms for pentoxifylline's actions are not fully understood. The drugincreases erythrocyte flexibility probably by inhibiting erythrocyte phosphodiesterase and decreases blood viscosity by reducing plasma fibrinogen and increasing fibrinolytic activity.Pentoxifylline is postulated to reduce negative endotoxic effects of cytokine mediators via itsphosphodiesterase inhibition.
Uses, Indications - In horses, pentoxifylline has been used as adjunctive therapy for endotoxemiaand in the treatment of navicular disease. At the time of writing, the drug is still under investigationto document both safety and efficacy for these purposes.
Pentoxifylline has been used in dogs to enhance healing and reduce inflammation caused by ulcerative dermatosis in Shelties and Collies and for other conditions where improved microcirculation may be of benefit.
Pentoxifylline's major indications for humans include symptomatic treatment of peripheral vascular disease (e.g., intermittent claudication, sickle cell disease, Raynaud's, etc.) and cerebrovasculardiseases where blood flow may be impaired in the microvasculature.
Pharmacokinetics
A pharmacokinetic study done in horses showed high interpatient variabilityin absorption of oral dosage forms with peak levels occurring 1 - 10 hours after oral dosing. Nosignificant difference in relative bioavailability was noted between whole and crushed extended-release tablets. The drug appears to rapidly eliminated (half life of about one hour after IV dosing).Because of the wide interpatient variability, the authors were unable to make dosingrecommendations for clinical use.
In humans, pentoxifylline absorption from the gastrointestinal tract is rapid and almost complete, but a significant first-pass effect occurs. Food affects the rate, but not the extent of absorption.
While the distributive characteristics have not been fully described, it is known that the drug entersmaternal milk. Pentoxifylline is metabolized both in the liver and in erythrocytes and all identifiedmetabolites appear to be active.
Contraindications, Precautions, Reproductive Safety
Pentoxifylline should be consideredcontraindicated in patients who have been intolerant to the drug or xanthines (e.g., theophylline, caffeine, theobromine) in the past and those with cerebral hemorrhage or retinal hemorrhage. Itshould be used cautiously in patients with severe hepatic or renal impairment and those at risk forhemorrhage.Although safety in pregnant, lactating or breeding animals has not been established, studies inpregnant rats and rabbits demonstrated no overt teratogenicity. As pentoxifylline and its metabolitesenter maternal milk, benefits to the mother should be weighed against the risks to offspring.
Adverse Effects, Warnings
Most commonly reported adverse effects involve the GI tract(vomiting/inappetence). There are reports of dizziness and headache occurring in a small percentageof humans receiving the drug. Other adverse effects, primarily GI, CNS and cardiovascular relatedhave been reported in people, but are considered to occur rarely. Note: Veterinary experience islimited with pentoxifylline and animal adverse effects may differ.Overdosage - Humans overdosed with pentoxifylline have demonstrated signs of flushing, seizures, hypotension, unconsciousness, agitation, fever, somnolence, GI distress and ECG changes.
One patient who ingested 80 mg/kg recovered completely. Overdoses should be treated using theusual methods of appropriate gut emptying and supportive therapies.
Drug Interactions
Use of non-steroidal antiinflammatory agents with pentoxifylline in horses iscontroversial. Some sources state that when used for endotoxemia in horses, pentoxyfilline'sbeneficial effects are negated by NSAIDs, but one study showed superior efficacy when flunixinand pentoxifylline were used together compared with either used alone.Ciprofloxacin (other quinolones too?) and cimetidine can increase pentoxifylline serum levels.
Increased adverse effects of pentoxifylline may result.
When pentoxifylline is used with warfarin or other anticoagulants, increased risk of bleeding mayresult. Use together with enhanced monitoring and caution. Theophylline blood levels may beincreased when used concurrently with pentoxifylline.