Re: parsing a line with $1, $2, $3

[CountZero]

I am not sure I understood fully your requirement, but here is my best try. It is not in one regex, but a combination of a split, a regex and a substitution.

use Modern::Perl;
use Data::Dump qw /dump/;

while (<DATA>) {
    chomp;
    my ($namedosageform, $instructions, $code) = grep {/\S/} split /<.
+*?>/;
    my ($name, $dosage, $form) = $namedosageform =~ /^([^\d]+)(\d+[^,]
++),\s*(.*)$/;
    $code =~ s/mfg codes:(.*)/$1/;
    say "Name: $name\nDosage: $dosage\nForm: $form\nInstructions: $ins
+tructions\nMFG codes: $code\n";
}

__DATA__
<h3>FENTANYL 25MCG/HR PATCH, TRANSDERMAL 72 HOURS</h3> <p class='cd1'>
+Restricted to NDC labeler code 50458 (Janssen) and to a maximum of te
+n (10) transdermal patches per dispensing and a maximum of three (3) 
+dispensings of any strength in a 75-day period only. </p><p>mfg codes
+:50458</p><p>DURAGESIC</p>
<h3>ACETAMINOPHEN 80MG/0.8ML SUSPENSION, DROPS(FINAL DOSAGE FORM)(ML)<
+/h3> <p class='cd1'>Restricted to individuals younger than 21 years o
+f age for the liquid and drops only. </p><p>mfg codes:68016, 63868, 6
+3162, 49348, 46122, 36800, 00904, 00536, 00472, 00113, 00067</p><p>TR
+IAMINIC FEVER REDUCER | PAIN & FEVER | NORTEMP | MAPAP INFANT | INFAN
+TS' NON-ASPIRIN | INFANT'S PAIN RELIEVER | INFANT'S PAIN RELIEF | INF
+ANT'S NON-ASPIRIN | ACETAMINOPHEN</p>

Output:

Name: FENTANYL 
Dosage: 25MCG/HR PATCH
Form: TRANSDERMAL 72 HOURS
Instructions: Restricted to NDC labeler code 50458 (Janssen) and to a maximum of ten (10) transdermal patches per dispensing and a maximum of three (3) dispensings of any strength in a 75-day period only. 
MFG codes: 50458

Name: ACETAMINOPHEN 
Dosage: 80MG/0.8ML SUSPENSION
Form: DROPS(FINAL DOSAGE FORM)(ML)
Instructions: Restricted to individuals younger than 21 years of age for the liquid and drops only. 
MFG codes: 68016, 63868, 63162, 49348, 46122, 36800, 00904, 00536, 00472, 00113, 00067