Adapter weights only for Qwen/Qwen2.5-7B-Instruct, fine-tuned to answer medical multiple-choice questions (A/B/C/D).
Subjects used for fine-tuning and evaluation: Biochemistry and Physiology.

Educational use only. Not medical advice.

What’s inside

adapter_model.safetensors (LoRA weights)
adapter_config.json
No tokenizer/template changes; load tokenizer from the base model

Quick use (Transformers + PEFT)

python

from transformers import AutoTokenizer, AutoModelForCausalLM
from peft import PeftModel
import re

BASE = "Qwen/Qwen2.5-7B-Instruct"
ADAPTER = "Pk3112/medmcqa-lora-qwen2.5-7b-instruct"

tok = AutoTokenizer.from_pretrained(BASE, use_fast=True)
base = AutoModelForCausalLM.from_pretrained(BASE, device_map="auto")
model = PeftModel.from_pretrained(base, ADAPTER).eval()

prompt = (
    "Question: Which nerve supplies the diaphragm?\n"
    "A. Vagus\nB. Phrenic\nC. Intercostal\nD. Accessory\n\n"
    "Answer:"
)
inputs = tok(prompt, return_tensors="pt").to(model.device)
out = model.generate(**inputs, max_new_tokens=8, do_sample=False)
text = tok.decode(out[0], skip_special_tokens=True)

m = re.search(r"Answer:\s*([A-D])\b", text)
print(f"Answer: {m.group(1)}" if m else text.strip())

Optional 4-bit: create a BitsAndBytesConfig and pass as quantization_config to from_pretrained (Linux/WSL recommended if using bitsandbytes).

Results (Biochemistry + Physiology)

Model	Internal val acc (%)	Original val acc (%)	TTFT (ms)	Gen time (ms)	In/Out tokens
Qwen2.5-7B (LoRA)	76.50	67.84	546	1623	81 / 15

Why Qwen as default: higher external-set accuracy and much lower latency vs Llama in our setup.

Training (summary)

Frameworks: Unsloth + PEFT/LoRA (QLoRA NF4)
LoRA: r=32, alpha=64, dropout=0.0; targets q_proj,k_proj,v_proj,o_proj,gate_proj,up_proj,down_proj
Max seq length: 768
Objective: answer-only target (Answer: <A/B/C/D>)
Split: stratified 70/30 on subject_name (Biochemistry, Physiology)

Training code & reproducibility

GitHub repo: https://github.com/PranavKumarAV/MedMCQA-Chatbot-Finetune-Medical-AI
Release (code snapshot): https://github.com/PranavKumarAV/MedMCQA-Chatbot-Finetune-Medical-AI/releases/tag/v1.0-medmcqa

License & usage

Adapter: Apache-2.0 (this repo)
Base model: Qwen/Qwen2.5-7B-Instruct (Apache-2.0) — obtain from its HF page
Dataset: openlifescienceai/medmcqa — follow dataset license
Safety: Educational use only. Not medical advice.