<?php
$patterns = [
    'prescribing_route' => '/\b(?:orally|oral|intravenous|\biv\b)\b/i',
    'prescribing_route_long' => '/\b(?:orally|oral|intravenous|intramuscular|subcutaneous|inhaled|nebulised|nebuli[sz]ed|topical|sublingual|rectal|transdermal|\biv\b|\bim\b|\bsc\b)\b/i',
    'hypogly_iv' => '/\b(?:intravenous|\biv\b|intramuscular|\bim\b|1\s*mg)\b/i',
];
foreach ($patterns as $name => $pat) {
    $r = @preg_match($pat, 'give iv fluids');
    $e = preg_last_error();
    echo $name, ' match=', var_export($r, true), ' err=', $e, PHP_EOL;
}
