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ProHeart 6 Adverse Drug Events: An Overview VMAC ProHeart 6 Meeting January 31, 2005 Lynn O. Post DVM, PhD FDA/CVM

Evaluation of Adverse Drug Events Observational Studies Advantages Larger and more diverse population Actual conditions of use Disadvantages Confounding factors No well defined control group

Reporting Rate Reporting rate Numerator =total number of spontaneously reported ADEs Denominatornumber of exposed patients ADE reporting rate is not an incidence rate ADEs are substantially under-reported (numerator). Accurate data on the number of exposed patients (denominator) is often lacking.

Reporting Rate Cont. A high reporting rate compared to the background incidence rate may signal a problem with a product. Because of under-reporting, the fact that a reporting rate is less than the background rate does not necessarily mean that the product in not associated with an increased risk of an adverse event.

Pre-approval History PH 6 Approved under NADA in June of 2001 Laboratory Studies No serious adverse drug events in healthy dogs Clinical field studies Vomiting, diarrhea, listlessness, weight loss, seizures, injection site pruritus, and increased body temperature

Pre-approval History PH 6 Cont. The death of 3 dogs (2 geriatric dogs and 1 dog with a history of health problems) resulted in the following PRECAUTION statement on the label: Use with caution in sick, debilitated or underweight animals.

Macrocyclic Lactone Toxicity Macrocyclic lactone toxicity in mammals Ivermectin, milbemycin oxime, and selamectin Toxic Signs Dilated pupils, vomiting, diarrhea, salivation, disorientation, lack of coordination, muscle twitching, tremors, depression, coma, and blindness. Severe reactions can involve other neurologic signs such as seizures which have been added to the post-approval safety information on several macrocyclic lactone labels

Post Approval History PH 6 Three label changes June 13, 2002, added reported clinical manifestations of: anaphylaxis/anaphylactoid reactions, depression/lethargy, urticaria, and head/facial edema. November 5, 2002, added cardiopulmonary signs associated with administration of the product in heartworm positive dogs

Post Approval History Cont. July 15, 2003, added a Client Information Sheet and the phrase “and rare reports of death”Client Information Sheet Two “Dear Doctor” Letters describing the three label changes (June 2002 and June 2003)

Annual Number of ProHeart 6 ADE Reports Received by CVM Period Initial reports Follow-up reports Total reports July 1, 2001-June 30, July 1, 2002-June 30, July 1, 2003-June 30,

Frequency of Initial and Follow-up ProHeart 6 Reports

Causality Assessments for All Clinical Manifestations Reported as PH 6 ADE’s Causality Assessment Category* Number of Assessments Definitely drug-related32** Probably drug-related4310 Possibly drug-related15334 Remotely drug-related2026 Information Lacking183 Total21885 *possibly, probably and definitely = positive causality (19676) **clinical manifestations that were considered definitely drug-related; all had causality assessment scores of +6 for heartworm ineffect

PH 6 Time of Onset*: Number of Causality Assessments *For those with known time of onset; causality ≥ 0

Moxidectin Mean Serum Concentration Following a Single Injection

Number of Dogs with Reported ADEs* Monthly and 6 Month Heartworm Preventives (Year of Initial Approval) Number of Dogs Approval to 9/1/04 Number of Dogs 9/6/01 to 9/1/04 Ivermectin Products (1987) Milbemycin Products (1990) Selamectin (1999) Moxidectin Tablets (1997) (ProHeart) 121 Moxidectin Sustained Release (2001) (ProHeart 6) 5659 *including “ineffect” for heartworms, hookworms, roundworms, fleas, ticks, and mites; causality ≥ 0

Number of Dog Deaths* Monthly and 6 Month Heartworm Preventives (Year of Initial Approval) Number of Deaths Approval to 9/1/04 Number of Deaths 6/6/01 to 9/1/04 Ivermectin Products (1987)13350 Milbemycin Products (1990)13159 Selamectin (1999) Moxidectin Tablets (1997) (ProHeart) 00 Moxidectin Sustained Release (2001) (ProHeart 6) 485 *causality assessment ≥ 0