2.1 General Information

PRIALT is intended for administration by or under the direction of a physician experienced in the technique of intrathecal administration and who is familiar with the drug and device labeling.

PRIALT is not intended for intravenous administration.

PRIALT is intended for intrathecal delivery using the Medtronic SynchroMed® II and SynchroMed® III Infusion System and CADD-Micro Ambulatory Infusion Pump [see Warnings and Precautions (5.2)]. Refer to the manufacturer's manual for specific instructions and precautions for programming the microinfusion device and/or refilling the reservoir.

PRIALT may be used for therapy undiluted (25 mcg/mL in 20 mL vial) or diluted (100 mcg/mL in 1 or 5 mL vials). The 100 mcg/mL formulation may be administered undiluted once an appropriate dose has been established.

Dilute PRIALT with 0.9% Sodium Chloride Injection, USP (preservative free) using aseptic procedures to the desired concentration prior to placement in the microinfusion pump.

• Saline solutions containing preservatives are not appropriate for intrathecal drug administration and should not be used due to risk of neurotoxicity.
• Refrigerate but do not freeze all PRIALT solutions after preparation and begin infusion within 24 hours.

Inspect vials of PRIALT visually for particulate matter and discoloration prior to administration whenever solution and container permit. Discard any PRIALT solution with observed particulate matter or discoloration and any unused portion left in the vial.

2.2 Dosing

2.3 Instructions for Use with the Medtronic SynchroMed II and SynchroMed III Infusion System

Refer to the manufacturer's manuals for specific instructions and precautions for performing a reservoir rinse, initial filling, refilling the reservoir, and programming. [see Warnings and Precautions (5.2)]

2.4 Instructions for Use in the CADD-Micro Ambulatory Infusion Pump

Refer to the manufacturer's manuals for specific instructions and precautions for performing the initial filling, refilling of the reservoir or replacement of the drug cartridge, and operation. The CADD-Micro Ambulatory Infusion Pump is filled for the first time with PRIALT solution at a concentration of 5 mcg/mL. This solution is prepared by diluting PRIALT with 0.9% Sodium Chloride, USP (preservative free).

The recommended initial flow rate for the external microinfusion is 0.02 mL/hr to deliver the initial dose rate of 2.4 mcg/day (0.1 mcg/hr) of PRIALT. Changes in dose rate are made by adjusting the flow rate of the infusion system and/or the concentration of PRIALT solution. [see Warnings and Precautions (5.2)]

5.1 Cognitive and Neuropsychiatric Adverse Reactions

Severe psychiatric symptoms and neurological impairment may occur during treatment with PRIALT. PRIALT is contraindicated in patients with a pre-existing history of psychosis. Monitor all patients frequently for evidence of cognitive impairment, hallucinations, or changes in mood or consciousness. PRIALT therapy can be interrupted or discontinued abruptly without evidence of withdrawal effects in the event of serious neurological or psychiatric signs or symptoms.

Events of acute psychiatric disturbances such as hallucinations (12%), paranoid reactions (3%), hostility (2%), delirium (2%), psychosis (1%), and manic reactions (0.4%) have been reported in patients treated with PRIALT. Patients with pretreatment psychiatric disorders may be at an increased risk. PRIALT may cause or worsen depression with the risk of suicide in susceptible patients. In placebo-controlled trials, there was a higher incidence of suicide, suicide attempts, and suicide ideations in PRIALT-treated patients than in the placebo group (0.27/patient year for PRIALT patients and 0.10/patient year for placebo patients).

Management of psychiatric complications may need to include discontinuation of PRIALT, treatment with psychotherapeutic agents and/or short-term hospitalization. Before drug is reinitiated, careful evaluation must be performed on an individual basis.

Use of PRIALT has been associated with cognitive impairment and decreased alertness/unresponsiveness. The following cognitive adverse reaction rates were reported: confusion (33%), memory impairment (22%), speech disorder (14%), aphasia (12%), thinking abnormal (8%), and amnesia (1%). Cognitive impairment may appear gradually after several weeks of treatment. Reduce the dose of PRIALT or discontinue the use of PRIALT if signs or symptoms of cognitive impairment develop, but other contributing causes must also be considered. The cognitive effects of PRIALT are generally reversible within 2 weeks after drug discontinuation. The median time to reversal of the individual cognitive effects ranged from 3 to 15 days. The elderly (≥ 65 years of age) are at higher risk for confusion. [see Use in Specific Populations (8.5)]

There may be additive effects on cognitive impairment and decreased alertness when PRIALT is used in conjunction with other CNS-depressant drugs that may necessitate dosage adjustments.

5.2 Meningitis and Other Infections

Meningitis can occur due to inadvertent contamination of the microinfusion device and other means such as CSF seeding due to hematogenous or direct spread from an infected pump pocket or catheter tract. While meningitis is rare with an internal microinfusion device and surgically-implanted catheter, the incidence increases substantially with external devices. In PRIALT clinical trials, meningitis occurred in 3% (40) of patients in the PRIALT group using either internal or external microinfusion devices and 1% (1 case) of patients in the placebo group.

The risk of meningitis was particularly high in patients with external microinfusion devices and catheters, occurring in 38 out of 41 patients (93%), 37 of whom received PRIALT and one who received placebo.

Patients, caregivers, and healthcare providers must be particularly vigilant for the signs and symptoms of meningitis, including but not limited to fever, headache, stiff neck, altered mental status (e.g., lethargy, confusion, disorientation), nausea or vomiting, and occasionally seizures. Serious infection or meningitis can occur within 24 hours of a breach in sterility such as a disconnected catheter, the most common cause of meningitis with external microinfusion devices. The patient and health care provider must be familiar with the handling of the external microinfusion device and care of the catheter skin exit site.

Strict aseptic procedures must be used during the preparation of the PRIALT solution and refilling of the microinfusion device to decrease the risk of introducing contaminants or other environmental pathogens into the reservoir. In suspected cases (especially in immuno-compromised patients) or in confirmed cases of meningitis, CSF cultures must be obtained and appropriate antibiotic therapy must be promptly instituted. Treatment of meningitis usually requires removal of the microinfusion system, catheter, and any other foreign body materials within the intrathecal space and, therefore, discontinuation of PRIALT therapy.

5.3 Reduced Level of Consciousness

Patients have become unresponsive or stuporous while receiving PRIALT. The incidence of unresponsiveness or stupor in clinical trials was 2% in PRIALT-treated patients. During these episodes, patients sometimes appear to be conscious and breathing is not depressed. If reduced levels of consciousness occur, discontinue PRIALT until the event resolves, and other etiologies (e.g., meningitis) must be considered. There is no known pharmacologic antagonist for this effect. Patients taking concomitant antiepileptics, neuroleptics, sedatives, or diuretics may be at higher risk of depressed levels of consciousness. If altered consciousness occurs, discontinue other CNS-depressant drugs as clinically appropriate.

5.4 Elevation of Serum Creatine Kinase

In clinical studies, 40% of PRIALT-treated patients had serum creatine kinase (CK) levels above the upper limit of normal (ULN), and 11% had CK levels that were greater than three times the ULN. In cases where CK was fractionated, only the muscle isoenzyme (MM) was elevated. The time to occurrence was sporadic, but the greatest incidence of CK elevation was during the first two months of treatment. One case of symptomatic myopathy with EMG findings, and two cases of acute renal failure associated with rhabdomyolysis and extreme CK elevations (17,000–27,000 IU/L) have been reported in PRIALT-treated patients.

Therefore, monitor serum CK in patients undergoing treatment with PRIALT periodically (e.g., every other week for the first month and monthly as appropriate thereafter). Evaluate patients clinically and obtain CK measurements in the setting of new neuromuscular symptoms (e.g., myalgias, myasthenia, muscle cramps, asthenia) or a reduction in physical activity. If these symptoms continue and CK levels remain elevated or continue to rise, reduce the dose or discontinue the use of PRIALT.

5.5 Withdrawal From Opiates

PRIALT is not an opiate and cannot prevent or relieve the symptoms associated with the withdrawal of opiates.

To avoid withdrawal syndrome when opiate withdrawal is necessary, do not abruptly reduce or withdraw opioid medications.

For patients being withdrawn from intrathecal opiates or intrathecal opiate infusion, gradually taper over a few weeks and replace with a pharmacologically equivalent dose of oral opiates.

5.6 Driving and Operating Machinery

Use of PRIALT has been associated with cognitive impairment and decreased alertness/unresponsiveness. Therefore, caution patients against engaging in hazardous activities that require complete mental alertness or motor coordination such as operating machinery or driving a motor vehicle.

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates in clinical practice.

A total of 1254 adult patients received PRIALT as a continuous infusion in acute and severe chronic pain trials with an exposure of 662 patient-years. The mean duration of treatment was 193 days with 173 patients (14%) treated for at least 1 year. The average final dose was 17.6 mcg/day (0.73 mcg/hr).

The most frequently reported adverse reactions (≥ 25%) in clinical trials were dizziness, nausea, confusional state and nystagmus. Slower titration of PRIALT may result in fewer serious adverse reactions and discontinuation of PRIALT for adverse reactions [see Clinical Studies (14) and Dosage and Administration (2)].

Adverse reactions during the slow titration placebo-controlled trial that occurred in 5% or greater of patients and more commonly with PRIALT than with placebo are summarized in Table 1.

6.2 Postmarketing Experience

The following adverse events have been reported during post-approval use of PRIALT. Because these events are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency or establish a causal relationship to drug exposure: Hypersensitivity reactions including angioedema, serious skin reactions including bullous dermatitis, skin ulcers, skin exfoliation, and burning skin sensation.

7.1 Interaction with CNS Depressants

Almost all patients in the PRIALT clinical trials received concomitant non-intrathecal medication. Most patients received several concomitant drugs, including antidepressants (66%), anxiolytics (52%), antiepileptics (47%), neuroleptics (46%), and sedatives (34%). The use of drugs with CNS-depressant activities may be associated with an increased incidence of CNS adverse reactions such as dizziness and confusion [see Warnings and Precautions (5)].

8.1 Pregnancy

8.2 Lactation

Risk Summary

There are no data on the presence of ziconotide in either human or animal milk, the effects on the breastfed infant, or the effects on milk production. Infants exposed to PRIALT through breast milk should be monitored for sedation which may result in respiratory depression and/or feeding problems. The developmental and health benefits of breastfeeding should be weighed against the mother´s clinical need for PRIALT and any potential adverse effect on the breastfed infant from PRIALT or from the underlying maternal condition.

8.4 Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

8.5 Geriatric Use

Of the total number of subjects in clinical studies of PRIALT, 22% were 65 and over, while 7% were 75 and over. In all trials, there was a higher incidence of confusion in older patients (42% for ≥ 65 year old versus 29% for < 65 year old subgroups). Other reported clinical experience has not identified differences in responses between elderly and younger patients. In general, the dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and of concomitant disease or other drug therapy.

12.1 Mechanism of Action

Ziconotide binds to N-type calcium channels located on the primary nociceptive (A-δ and C) afferent nerves in the superficial layers (Rexed laminae I and II) of the dorsal horn in the spinal cord. Although the mechanism of action of ziconotide has not been established in humans, results in animals suggest that its binding blocks N-type calcium channels, which leads to a blockade of excitatory neurotransmitter release from the primary afferent nerve terminals and antinociception.

12.2 Pharmacodynamics

Interaction with Opioids

Ziconotide does not bind to opioid receptors and its pharmacological effects are not blocked by opioid antagonists. In animal models, intrathecal ziconotide potentiated opioid-induced reduction in gastrointestinal (GI) motility, but did not potentiate morphine-induced respiratory depression. In rats receiving ziconotide, additive analgesic effects were observed with concurrent administration of morphine, baclofen, or clonidine. Concurrent administration of intrathecal ziconotide and morphine did not prevent the development of morphine tolerance in rats.

12.3 Pharmacokinetics

The cerebrospinal fluid (CSF) pharmacokinetics (PK) of ziconotide have been studied after one-hour intrathecal infusions of 1 to 10 mcg of PRIALT to patients with chronic pain. The plasma PK following intravenous infusion (0.3 to 10 mcg/kg/day) have also been studied. Both intrathecal and intravenous data are shown below (Table 2).

Following one-hour intrathecal administration of 1 to 10 mcg of PRIALT, both total exposure (AUC; range: 83.6 to 608 ng•h/mL) and peak exposure (Cmax; range: 16.4 to 132 ng/mL) values in the CSF were variable and dose-dependent, but appeared approximately dose-proportional. During 5 or 6 days of continuous intrathecal infusions of PRIALT at infusion rates ranging from 0.1 to 7.0 mcg/hr in patients with chronic pain, plasma ziconotide levels could not be quantified in 56% of patients using an assay with a lower limit of detection of approximately 0.04 ng/mL. Predictably, patients requiring higher intrathecal infusion dose rates were more likely to have quantifiable ziconotide levels in plasma. Plasma ziconotide levels, when detectable, remain constant after many months of intrathecal PRIALT infusion in patients followed for up to 9 months.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

No carcinogenicity studies have been conducted in animals.

Mutagenesis

Ziconotide was negative in the in vitro bacterial reverse mutation assay, in vitro mouse lymphoma assay, in vivo mouse micronucleus assay, and in the in vitro Syrian hamster embryo (SHE) cell transformation assay.

Impairment of Fertility

Ziconotide did not affect male fertility in rats when administered as a continuous intravenous infusion at a dose of up to 10 mg/kg/day when administered for approximately 8 weeks, including a 28-day pre-mating period, or female fertility at a dose of 3 mg/kg/day when administered for approximately 6 weeks, including a 14-day pre-mating period. Estimated exposures for the male and female rats were approximately 6500-fold and 1700-fold higher, respectively, than the expected exposure resulting from the maximum recommended human daily intrathecal dose of 0.8 mcg/hr (19.2 mcg/day) based on plasma exposure.

Female fertility in rats was significantly affected following continuous intravenous infusion at a dose of 10 mg/kg/day. Significant reductions in corpora lutea, implantation sites, and number of live fetuses were observed.

14.1 Laboratory Tests

Monitor serum CK in patients undergoing treatment with PRIALT periodically (e.g., every other week for the first month and monthly as appropriate thereafter). Evaluate patients clinically and obtain CK measurements in the setting of new neuromuscular symptoms (e.g., myalgias, myasthenia, muscle cramps, asthenia) or a reduction in physical activity. If these symptoms continue and CK levels remain elevated or continue to rise, reduce the dose or discontinue the use of PRIALT.

16.1 How Supplied

PRIALT is supplied as a 25 mcg/mL solution in a single-use 20 mL glass vial and as a 100 mcg/mL solution in single-use glass vials containing 1 mL or 5 mL of solution. One vial is packaged per carton.

Presentation (NDC)

25 mcg/mL: 20 mL vial (70720-723-10). Only the undiluted 25 mcg/mL formulation should be used for PRIALT naïve pump priming.

100 mcg/mL: 1 mL vial (70720-720-10)
 5 mL vial (70720-722-10)

16.2 Storage

• Refrigerate PRIALT during transit.
• Store PRIALT at 2°C to 8°C (36°F to 46°F).
• PRIALT, once diluted aseptically with saline, may be stored at 2°C to 8°C for 24 hours.
• Do NOT freeze PRIALT.
• Protect from light.