diff --git a/litellm/llms/anthropic/chat/transformation.py b/litellm/llms/anthropic/chat/transformation.py
index 86f4832c2a..b88b7e7126 100644
--- a/litellm/llms/anthropic/chat/transformation.py
+++ b/litellm/llms/anthropic/chat/transformation.py
@@ -1073,6 +1073,9 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
         ):
             optional_params["metadata"] = {"user_id": _litellm_metadata["user_id"]}
 
+        # Remove internal LiteLLM parameters that should not be sent to Anthropic API
+        optional_params.pop("is_vertex_request", None)
+
         data = {
             "model": model,
             "messages": anthropic_messages,