Combination Intrathecal Drug Therapy Strategies for Pain Management

BACKGROUND

Numerous combination intrathecal drug therapy (CIDT) strategies exist and are utilized for varying pain syndromes, typically when monotherapy dose escalation or medication alternation is deemed untenable or unfeasible. Unfortunately, the supportive evidence basis for the use of these strategies and specific drug combinations is generally lacking and unclear, with many medications being used for off-label indications.

OBJECTIVE

In this manuscript, we provide a robust exploration and analysis of the literature to provide an evidence-based narrative for the use of CIDT strategies in regard to clinical indications, pharmacologic parameters, specific drug combinations, safety profiles, and future directions.

STUDY DESIGN

Narrative review.

METHODS

This was an evidence based narrative performed after extensive review of the literature.

RESULTS

Variances in intrathecal pharmacokinetics and pharmacodynamics are utilized advantageously with CIDT strategies to achieve improved analgesic benefit; however, appropriate use may be limited by increased or compounded risk of adverse effects. The supportive evidence for CIDT use for chronic pain conditions is largely lacking and limited to small, uncontrolled, observational studies, with many having various confounding factors, including a lack of standardized dosing. The most evidenced CIDT strategies include polyanalgesia with morphine-ziconotide, opioid-clonidine, and morphine-bupivacaine. Notably, in addition to pain relief, morphine-bupivacaine has been shown to decrease early opioid escalation requirements.

LIMITATIONS

The supportive evidence for CIDT use for chronic pain conditions is largely lacking and limited to small, uncontrolled, observational studies, with many having various confounding factors including a lack of standardized dosing.

CONCLUSIONS

CIDT strategies and polyanalgesia combinations can be effective for treating various patient populations with chronic pain. The appropriate use of these strategies may be limited by increased or compounded risk of adverse effects, both of which are highly patient and scenario dependent. Therefore, practitioners should maintain a particularly low threshold of suspicion for adverse effects in patients with CIDT such that safety profiles associated with this therapy can be favorably maintained.

Transition from Compounded to Monotherapy Intrathecal Pain Medication Reduces Drug Costs: Retrospective Analysis of Patient Billing Data

BACKGROUND

Chronic pain accounts for several hundred billion dollars in total treatment costs, and lost productivity annually. Selecting cost-effective pain treatments can reduce the financial burden on both individuals and society. Targeted drug delivery (TDD), whereby medications used to treat pain are delivered directly to the intrathecal space, remains an important treatment modality for chronic pain refractory to oral medication management. These medications can be administered alone (monotherapy), or in conjunction with other medications to give a synergistic affect (compounded therapy). While compounded therapy is often prescribed for pain refractory to both oral management and intrathecal monotherapy, compounded administration has not been approved by the United States Food and Drug Administration (FDA), and is thought to be more expensive. In this study, we hypothesized that TDD delivering monotherapy vs compounded therapy would differ significantly in cost.

OBJECTIVES

In 2015, a pharmacy-led initiative resulted in an institution-wide policy requiring that all TDD patients, being treated with compounded therapy, be transitioned to FDA-approved intrathecal monotherapy. The intent of this new policy was to eliminate use of non-FDA approved, "off-label" medications. During this transition, our practice used the opportunity to retrospectively analyze and compare the costs of monotherapy vs compounded therapy.

STUDY DESIGN

Billing, drug dosing, and pain data were collected from 01/2015 to 01/2019, and reviewed retrospectively for patients originally on compounded intrathecal medication therapy, and compared before and after transition to monotherapy.

SETTING

A multidisciplinary hospital-based spine center within an academic tertiary care facility.

METHODS

Electronic medical records from the institutional TDD program were retrospectively reviewed to identify all patients on compounded drug therapy before the transition period (2015-2016). Patients were excluded from the study if they chose to switch their care to another practice rather than transitioning from compounded therapy to monotherapy. Cost per medications refill, cost per year, and reported pain scale before and after the transition were computed, and differences were compared using unpaired t tests. Refill costs of individual drugs were also compared.

RESULTS

Of 46 patients originally on compounded therapy, 26 patients met inclusion criteria. The most common pre-transition drugs administered as compounded therapy were bupivacaine (n = 17), morphine (n = 15), and clonidine (n = 14), while hydromorphone (n = 10), baclofen (n = 5), and fentanyl (n = 1) were less common. There was a 51.3% decrease in cost per refill (P = 0.135) and a 50.0% decrease in cost per year (P = 0.283) after transition. Morphine and clonidine were both significantly more expensive than hydromorphone and bupivacaine (P < 0.05). After removing cases in which hydromorphone was the baseline opiate, there was a 64.8% decrease in cost per refill (P = 0.041) and a 66.8% decrease in cost per year (P = 0.190). There was no significant difference in the average reported pain scale across the transition (P = 0.323), suggesting stable pain management efficacy.

LIMITATIONS

This retrospective study is limited by its small cohort size and lack of a control group.

CONCLUSIONS

Based on single-institutional billing data, transition from compounded therapy to monotherapy TDD resulted in cost savings, dependent on the specific combination of drugs initially used for therapy. A larger multi-institutional study is indicated.