One drug or two-the risks and benefits of combining psychotropic medications (Proceedings)

Factors to consider before prescribing a psychoactive drug

Does this patient need a drug?

      What is the diagnosis?

      What is the intensity of the behavior?

      Has prior therapy been appropriately implemented?

           Examine past behavioral and environmental modification steps

Selecting the primary medication

      Mechanism of action

           Class of medication

           TCA

           SSRI

           Benzodiazepine

           MAOi

      Type of medication

Licensed drug

      Extra-label vs FDA approved

Nutriceutical

Herbal

      Familiarity of prescriber with the product

      Client factors

            Cost

            Tolerance for side effects

      Pet factors

            Concurrent medical conditions & medications

            Risk of side effects

Evaluating the response to single drug therapy

      Side effects

            Physical

            Behavioral

      Effect on target behavior

            Percent improvement

                 If inadequate, has there been enough time for full response?

                  Reevaluate dosage

Indications for combination therapy

      Slow onset chronic drug may be temporarily paired with rapid onset drug

      Partial response to primary drug at adequate dose

      Dosage of primary drug cannot be increased without intolerable side effects

Will the combination be safe?

      Consider inhibition or potentiation of cytochrome p450 enzyme systems

      Side effects may be additive

      Dosage adjustments may be needed

            Prepare to adjust dosages of non-psychotropic medications

      Some drugs combinations are contraindicated

            Eg no MAO with SSRI

Selecting adjunct medication

      Diagnosis and intensity of behavior problem(s)

      Age, overall health and species of patient

      Side profile of primary drug

      Time to therapeutic effect

      Class of drug

            Need extra care if two drugs are in the same family

            Serotonin syndrome

Patient monitoring for patients on multiple drug regimen

Pretreatment baseline laboratory testing

      CBC / serum chemistry profile / thyroid baseline

Reassess CBC / serum chemistry profile in one month and three months

Additional retesting every 3 – 6 months

Client consent

The use of many psychotropic medications in animals may still be viewed as experimental. Extra-label use of drugs is common practice. There is little published information available regarding combination therapy. A decision to use multiple medications should be made with full client consent, and with the understanding that the potential benefit to the patient outweighs any risk.

Behavior modification

It is rare for psychoactive drugs to be sufficient to eliminate or adequately control most behavior problems. Environmental and behavioral modification may be at least as important as the pharmacological intervention. During follow-up evaluations, confirm that clients are implementing the prescribed interventions appropriately. Offer additional treatment strategies as the patient continues to improve.