\documentclass{article}
\usepackage{threeparttable}
\usepackage{multirow}
\usepackage{booktabs}
\usepackage{xcolor}
\usepackage{tikz}
\begin{document}
\begin{table}[!ht]
\setlength\tabcolsep{0pt}
\centering
\begin{threeparttable}
\begin{tabular}{@{\extracolsep{2ex}}*{4}{lllc}}
\toprule
\textbf{id} & \textbf{dose} &  & \textbf{value} \\
\midrule
\multirow[t]{2}{*}{1} & 1 mg & \textbf{mean} & 5 \\
 & 50 mg & \textbf{mean} & 2 \\
\multirow[t]{2}{*}{5} & 1 mg & \textbf{mean} & 1 \\
 & 50 mg & \textbf{mean} & 2 \\
\multirow[t]{2}{*}{8} & 1 mg & \textbf{mean} & 2 \\
 & 50 mg & \textbf{mean} & 3 \\
\multirow[t]{2}{*}{10} & 5 mg & \textbf{mean} & 4 \\
 & 10 mg & \textbf{mean} & 5 \\
\multirow[t]{2}{*}{50} & 5 mg & \textbf{mean} & 3 \\
 & 10 mg & \textbf{mean} & 4 \\
\multirow[t]{2}{*}{80} & 5 mg & \textbf{mean} & 1 \\
 & 10 mg & \textbf{mean} & 4 \\
\bottomrule
\end{tabular}
\end{threeparttable}
\end{table}
\end{document}