Concept: American Hospital Formulary Service (AHFS) Pharmacologic-Therapeutic Classification System

Introduction

The AHFS system for classifying drugs is commonly used in North America. This system is updated once a year, and is published as a book by the American Society of Health-System Pharmacists ( http://www.ashp.org/ ). See AHFS Drug Information Web Site at: http://www.ahfsdruginformation.com/ for more information.

The AHFS code is a 6 digit number which includes three levels of information arranged in a step-up / step-down manner. For example, all AHFS codes starting with 20 represent a broad class of drugs for Blood Formation and Coagulation. Additional information is provided for sub-categories of this class as digits are added:

Example:

20:00 Blood Formation and Coagulation
20:04 Anti-anemia Drugs
20:04.04 Iron Preparations
20:04.08 Liver and Stomach Preparations

In Manitoba, the top 20 AHFS categories dispensed to residents for 1996 are provided below. These categories have been ranked by the number of claims. They represent 73.3% of all drug claims for that year.

	AHFS Classification	# of claims	% of claims
1	24:04.00 Cardiac Drugs	690,884	10.30
2	08:12.16 Penicillins	479,336	7.14
3	28:08.04 Nosteroidal Anti-inflammatory Agents	363,463	5.42
4	28:08.08 Opiate Agonists	338,537	5.05
5	28:24.08 Benzodiazepines	331,469	4.94
6	28:16.04 Antidepressants	329,410	4.91
7	56:40.00 Misc GI Drugs	303,629	4.53
8	40:28.00 Diuretics	261,365	3.90
9	68:12.00 Contraceptives	257,689	3.84
10	12:12.00 Sympathomimetic Agents	244,971	3.65
11	84:06.00 Anit-inflammatory Agents	169,159	2.52
12	92:00.00 Unclassified Therapeutic Agents	154,618	2.30
13	08:12.12 Macrolides	153,869	2.29
14	08:40.00 Misc Anti-infectives	141,349	2.11
15	24:06.00 Antilipemic Agents	131,702	1.96
16	24:12.00 Vasodilating Agents	128,248	1.91
17	68:04.00 Adrenals	116,982	1.74
18	68:16.00 Estrogens	112,034	1.67
19	68:20.20 Sulfonylureas	107,044	1.60
20	52:08.00 EENT Anti-inflammatory Agents	101,229	1.51
	Totals =	4,916,987	73.28