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>

[download]
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

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

My blog: Imperial Deltronics

In reply to Re: parsing a line with $1, $2, $3 by CountZero
in thread parsing a line with $1, $2, $3 by kevyt

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